Flysch

@book{bouma1962sedimentology1,
    author = "Bouma, A. H",
    title = "Sedimentology of some flysch deposits",
    year = "1962",
    publisher = "Amsterdam, Elsevier, 168 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Bouma, A. H., 1962, Sedimentology of some flysch deposits: Amsterdam, Elsevier, 168 p.}"
}

@book{openalexw1570283708,
    author = "Bouma, Arnold H. and Kuenen, Philip Henry and Shepard, Francis P.",
    title = "Sedimentology of some Flysch deposits: a graphic approach to facies interpretation",
    year = "1962",
    url = "https://openalex.org/W1570283708",
    openalex = "W1570283708"
}

@book{openalexw3120543430,
    author = "Bouma, Arnold H.",
    title = "Sedimentology of Some Flysch Deposits",
    year = "1962",
    journal = "Medical Entomology and Zoology",
    url = "https://openalex.org/W3120543430",
    openalex = "W3120543430"
}

Abstract The composition, mode of appearance, and the alternation in the flysch deposits of the Yugoslavian Dinarides indicates that they are of orogenic origin, formed during a period of emergence of cordilleras and sunken synclinal troughs. The terrigenous material came from land bordering the sea and from the basement rocks and the overlying deposits of the cordillera. The flysch deposition was preceded by a period of folding. The molasse deposits (Eocene to Miocene) were formed in the final phase of the geosyncline. Differences and similarities between molasse and flysch deposits indicate that the molasse is fossiliferous and usually contains carbon and bituminous shales, while the flysch has no macrofauna and a sparse microfauna. The conglomerate series in the flysch is not recognized in the molasse. The flysch formations in the area are Anisian, Albian-Cenomanian, Maestrichtian-Danian, and upper Eocene.

@article{doi102113gssgfbulls7vii3499,
    author = "Ciric, Branislav",
    title = "Sur les flyschs et les molasses du cycle alpin dans les Dinarides yougoslaves",
    year = "1965",
    journal = "Bulletin de la Société Géologique de France",
    abstract = "Abstract The composition, mode of appearance, and the alternation in the flysch deposits of the Yugoslavian Dinarides indicates that they are of orogenic origin, formed during a period of emergence of cordilleras and sunken synclinal troughs. The terrigenous material came from land bordering the sea and from the basement rocks and the overlying deposits of the cordillera. The flysch deposition was preceded by a period of folding. The molasse deposits (Eocene to Miocene) were formed in the final phase of the geosyncline. Differences and similarities between molasse and flysch deposits indicate that the molasse is fossiliferous and usually contains carbon and bituminous shales, while the flysch has no macrofauna and a sparse microfauna. The conglomerate series in the flysch is not recognized in the molasse. The flysch formations in the area are Anisian, Albian-Cenomanian, Maestrichtian-Danian, and upper Eocene.",
    url = "https://doi.org/10.2113/gssgfbull.s7-vii.3.499",
    doi = "10.2113/gssgfbull.s7-vii.3.499",
    openalex = "W2530972056"
}

SUMMARY After a brief review of the structure, the stratigraphy and the facies of the Rumanian eastern Carpathians flysch zone, the authors analyse the main paleocurrent directions on the internal facies of the paleogene flysch. The most important and numerous currents were longitudinal and came into the flysch trough from an outlet area situated in the Carpathian arc region. For this reason it is inferred that the principal source of detrital material was represented by the Pannonian–Transylvanian internal massif. The crystalline core of the eastern Carpathians furnished only a small quantity of clastics, which were transported into the trench by means of transversal, relatively weak currents. The role of different structural elements (platforms, cordilleras, internal massifs) in providing detrital material is briefly discussed. Finally, an attempt is made to outline the paleogeographic evolution of the eastern Carpathians during the Paleogene.

@article{doi101111j136530911966tb01297x,
    author = "Contescu, Lorin R. and Jipa, Dan C. and Mihailescu, N and Panin, Nicolae",
    title = "THE INTERNAL PALEOGENE FLYSCH OF THE EASTERN CARPATHIANS: PALEOCURRENTS, SOURCE AREAS AND FACIES SIGNIFICANCE",
    year = "1966",
    journal = "Sedimentology",
    abstract = "SUMMARY After a brief review of the structure, the stratigraphy and the facies of the Rumanian eastern Carpathians flysch zone, the authors analyse the main paleocurrent directions on the internal facies of the paleogene flysch. The most important and numerous currents were longitudinal and came into the flysch trough from an outlet area situated in the Carpathian arc region. For this reason it is inferred that the principal source of detrital material was represented by the Pannonian–Transylvanian internal massif. The crystalline core of the eastern Carpathians furnished only a small quantity of clastics, which were transported into the trench by means of transversal, relatively weak currents. The role of different structural elements (platforms, cordilleras, internal massifs) in providing detrital material is briefly discussed. Finally, an attempt is made to outline the paleogeographic evolution of the eastern Carpathians during the Paleogene.",
    url = "https://doi.org/10.1111/j.1365-3091.1966.tb01297.x",
    doi = "10.1111/j.1365-3091.1966.tb01297.x",
    openalex = "W2088134820"
}

The Quaternary deposits of the Alboran Sea and associated sediment dispersal patterns, and geographic and tectonic setting of the region, are closely similar to those of some ancient flysch basins preserved in the geological record.

@article{doi101038228979a0,
    author = "Stanley, D J and Gehin, C E and Bartolini, C",
    title = "Flysch-type sedimentation in the Alboran Sea, Western Mediterranean.",
    year = "1970",
    journal = "Nature",
    abstract = "The Quaternary deposits of the Alboran Sea and associated sediment dispersal patterns, and geographic and tectonic setting of the region, are closely similar to those of some ancient flysch basins preserved in the geological record.",
    url = "https://pubmed.ncbi.nlm.nih.gov/16059023/",
    doi = "10.1038/228979a0",
    openalex = "W2085079624",
    pmid = "16059023",
    references = "doi101016002532276690003x, doi101016s0070457108709543, doi101130001676061959701089tifotp20co2, doi10113000167606195970291smitao20co2, doi10113000167606196071843peotca20co2, doi101130001676061965761251spitds20co2, doi101130001676061965761261sottap20co2, doi101785bssa0590010369"
}

@article{arkhipov1972contrast,
    author = "Arkhipov, I.V.",
    title = "Contrast between flysch and nonflysch deposits",
    year = "1972",
    journal = "International Geology Review",
    url = "https://doi.org/10.1080/00206817209475754",
    doi = "10.1080/00206817209475754",
    number = "7",
    openalex = "W2086645927",
    pages = "720-728",
    volume = "14",
    references = "doi1010079783642948992, doi101016s0016787863800280, doi101016s0070457109062128, doi1010970001069419650700000019, doi101111j136530911966tb01297x, doi10113000167606194758979fam20co2, doi10113000167606195768543fs20co2, doi102113gssgfbulls7vii3499"
}

@incollection{dumitriu1972monte,
    author = "Dumitriu, Mircea and Dumitriu, Cristina",
    title = "Monte Carlo Simulation of Some Flysch Deposits from the East Carpathians",
    year = "1972",
    booktitle = "Computer Applications in the Earth Sciences",
    url = "https://doi.org/10.1007/978-1-4684-1995-5\_5",
    doi = "10.1007/978-1-4684-1995-5\_5",
    openalex = "W201330629",
    pages = "115-123",
    references = "openalexw1590525445, openalexw571657687, openalexw630529900"
}

ABSTRACT A clear distinction must be made between liquefied and fluidized systems. In liquefied beds and flows, the solids settle downward through the fluid, displacing it upward, whereas, in fluidized beds, the fluid moves upward through the solids, which are temporarily suspended without net downward movement. Many recent references to fluidized sediment gravity flows refer, in fact, to flows of liquefied debris. Most uniformly liquefied beds of well‐sorted sand‐ or gravel‐sized sediment will resediment as simple two‐layer systems. Liquefied flows can originate either by liquefaction followed by failure, as in many retrogressive flow slides, or by failure followed by liquefaction, as in the case of some slumps. Empirical and theoretical estimates of flow velocity, thickness, and travel distance suggest that natural laminar liquefied flows of fine‐grained sand will generally resediment after moving a kilometre or less. Laminar flows of coarse‐grained sand will resediment after moving only a few metres. Grain dispersive pressure is thought to be of little significance in the development or maintenance of liquefied flows. Many surficial submarine sand beds are apparently susceptible to liquefaction, including submarine canyon and continental rise deposits. Within submarine canyons and narrow fjords, steep slopes and channels promote the evolution of liquefied flows from slumps by liquefaction after failure and of high density turbidity currents from liquefied flows by the development of turbulence. Upon moving into the lower parts of submarine canyons or into proximal fan channels, liquefied flows will resediment and high density turbidity currents will tend to decline to flows transitional between liquefied flows and turbidity currents. The liquefied, coarser detritus within such transitional flows will be deposited while finer‐grained debris will remain in suspension and continue downslope as dilute turbidity currents. Resedimentation of the liquefied portions of such flows may be responsible for the deposition of the A‐subdivision of many turbidites and many thick, structureless ‘proximal turbidites’ or ‘fluxoturbidites’. Similar units can originate by liquefaction of the traction deposits of normal turbidity currents. Fluidized flows are probably uncommon, thin, and, where formed, originate through fluidization of the fine‐grained tops of liquefied graded beds.

@article{doi101111j136530911976tb00051x,
    author = "Lowe, Donald R.",
    title = "Subaqueous liquefied and fluidized sediment flows and their deposits",
    year = "1976",
    journal = "Sedimentology",
    abstract = "ABSTRACT A clear distinction must be made between liquefied and fluidized systems. In liquefied beds and flows, the solids settle downward through the fluid, displacing it upward, whereas, in fluidized beds, the fluid moves upward through the solids, which are temporarily suspended without net downward movement. Many recent references to fluidized sediment gravity flows refer, in fact, to flows of liquefied debris. Most uniformly liquefied beds of well‐sorted sand‐ or gravel‐sized sediment will resediment as simple two‐layer systems. Liquefied flows can originate either by liquefaction followed by failure, as in many retrogressive flow slides, or by failure followed by liquefaction, as in the case of some slumps. Empirical and theoretical estimates of flow velocity, thickness, and travel distance suggest that natural laminar liquefied flows of fine‐grained sand will generally resediment after moving a kilometre or less. Laminar flows of coarse‐grained sand will resediment after moving only a few metres. Grain dispersive pressure is thought to be of little significance in the development or maintenance of liquefied flows. Many surficial submarine sand beds are apparently susceptible to liquefaction, including submarine canyon and continental rise deposits. Within submarine canyons and narrow fjords, steep slopes and channels promote the evolution of liquefied flows from slumps by liquefaction after failure and of high density turbidity currents from liquefied flows by the development of turbulence. Upon moving into the lower parts of submarine canyons or into proximal fan channels, liquefied flows will resediment and high density turbidity currents will tend to decline to flows transitional between liquefied flows and turbidity currents. The liquefied, coarser detritus within such transitional flows will be deposited while finer‐grained debris will remain in suspension and continue downslope as dilute turbidity currents. Resedimentation of the liquefied portions of such flows may be responsible for the deposition of the A‐subdivision of many turbidites and many thick, structureless ‘proximal turbidites’ or ‘fluxoturbidites’. Similar units can originate by liquefaction of the traction deposits of normal turbidity currents. Fluidized flows are probably uncommon, thin, and, where formed, originate through fluidization of the fine‐grained tops of liquefied graded beds.",
    url = "https://doi.org/10.1111/j.1365-3091.1976.tb00051.x",
    doi = "10.1111/j.1365-3091.1976.tb00051.x",
    openalex = "W2066663496",
    references = "doi101002aic690120343, doi1010160016003268900380, doi1010160032591069800872, doi1010160095852251900360, doi101016s0263876297800068, doi101061jsfeaq0000913, doi101111j136530911975tb00290x, doi101130001676061959701089tifotp20co2, doi102475ajs25012849, doi102475ajss525148325, openalexw1587261652"
}

Stratigraphic relationships indicate that late Quaternary outwash near Ottawa, Canada, was deposited close to the ice front and below wave base in the Champlain Sea and/or an earlier ice-dammed lake. Distinct sand and coarse gravel facies are present, the latter with clast long axes parallel to flow, indicating deposition from a high energy current with high clast concentration.The sand facies contain channels up to 10 m deep and 40 m wide, filled with essentially massive sand. In some cases the base and basal fill are contorted into ball-and-pillow structures, and the channels contain dish structures and scattered pebbles. Similar features occur in the channeled sands of deep sea submarine fan valleys, and are thought to indicate rapid deposition by a mass flow mechanism, with high sediment concentration and low turbulence. In the present case, deformation at the channel bases probably resulted from liquefaction due to rapid sediment loading; dewatering gave rise to dish structures at higher levels. Possible mechanisms for initiating mass flows include shock waves generated by iceberg calving, and the effects of rapid changes in water level and salinity as the Champlain Sea invaded the area.

@article{doi101139e77020,
    author = "Rust, Brian R.",
    title = "Mass flow deposits in a Quaternary succession near Ottawa, Canada: diagnostic criteria for subaqueous outwash",
    year = "1977",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "Stratigraphic relationships indicate that late Quaternary outwash near Ottawa, Canada, was deposited close to the ice front and below wave base in the Champlain Sea and/or an earlier ice-dammed lake. Distinct sand and coarse gravel facies are present, the latter with clast long axes parallel to flow, indicating deposition from a high energy current with high clast concentration.The sand facies contain channels up to 10 m deep and 40 m wide, filled with essentially massive sand. In some cases the base and basal fill are contorted into ball-and-pillow structures, and the channels contain dish structures and scattered pebbles. Similar features occur in the channeled sands of deep sea submarine fan valleys, and are thought to indicate rapid deposition by a mass flow mechanism, with high sediment concentration and low turbulence. In the present case, deformation at the channel bases probably resulted from liquefaction due to rapid sediment loading; dewatering gave rise to dish structures at higher levels. Possible mechanisms for initiating mass flows include shock waves generated by iceberg calving, and the effects of rapid changes in water level and salinity as the Champlain Sea invaded the area.",
    url = "https://doi.org/10.1139/e77-020",
    doi = "10.1139/e77-020",
    openalex = "W2036512612",
    references = "coleman1965sedimentary, doi101086627725, doi101130001676061959701089tifotp20co2, doi10113000167606197586737gfmfrc20co2"
}

Abstract This article serves as an introduction to the papers dealing with braided river deposits in this volume. A lithofacies code erected earlier by the writer is expanded to include matrix-supported gravel, low-angle cross stratified sand, erosion surfaces with intraclast conglomerates, and massive mud deposits. The four vertical profile models erected by the writer are expanded to six. A new model, the “Trollheim type” is proposed, to include gravelly deposits characterized by abundant debris flows. The Donjek sequence type is restricted to gravel-dominated cyclic deposits and a new model, the “South Saskatchewan type”, is erected for sand dominated cyclic deposits. The Scott, Platte and Bijou Creek models remain essentially unchanged.

@article{openalexw1912927042,
    author = "Miall, Andrew D.",
    title = "Lithofacies Types and Vertical Profile Models in Braided River Deposits: A Summary",
    year = "1977",
    abstract = "Abstract This article serves as an introduction to the papers dealing with braided river deposits in this volume. A lithofacies code erected earlier by the writer is expanded to include matrix-supported gravel, low-angle cross stratified sand, erosion surfaces with intraclast conglomerates, and massive mud deposits. The four vertical profile models erected by the writer are expanded to six. A new model, the “Trollheim type” is proposed, to include gravelly deposits characterized by abundant debris flows. The Donjek sequence type is restricted to gravel-dominated cyclic deposits and a new model, the “South Saskatchewan type”, is erected for sand dominated cyclic deposits. The Scott, Platte and Bijou Creek models remain essentially unchanged.",
    openalex = "W1912927042",
    references = "doi1010160037073878900015, doi101086627271, doi101111j136530911972tb00013x, doi101111j136530911973tb01615x, doi101111j136530911977tb01915x, doi101111j146783061963tb00464x, doi10113000167606195465175goafis20co2, doi101139e76010, doi10130674d71cf32b2111d78648000102c1865d, doi102475ajs2668609"
}

@incollection{doi102110pec79270075,
    author = "Lowe, Donald R.",
    title = "SEDIMENT GRAVITY FLOWS: THEIR CLASSIFICATION AND SOME PROBLEMS OF APPLICATION TO NATURAL FLOWS AND DEPOSITS",
    year = "1979",
    booktitle = "SEPM (Society for Sedimentary Geology) eBooks",
    url = "https://doi.org/10.2110/pec.79.27.0075",
    doi = "10.2110/pec.79.27.0075",
    openalex = "W1589890367"
}

ABSTRACT Four principal mechanisms of deposition are effective in the formation of sediment gravity flow deposits. Grains deposited by traction sedimentation and suspension sedimentation respond individually and accumulate directly from bed and suspended loads, respectively. Those deposited by frictional freezing and cohesive freezing interact through either frictional contact or cohesive forces, respectively, and are deposited collectively, usually by plug formation. Sediment deposition from individual sediment flows commonly involves more than one of these mechanisms acting either serially as the flow evolves or simultaneously on different grain populations. Deposition from turbidity currents is treated in terms of three dynamic grain populations: 1) clay- to medium-grained sand-sized particles that can be fully suspended as individual grains by flow turbulence, 2) coarse-grained sand to small-pebble-sized gravel that can be fully suspended in large amounts mainly in highly concentrated turbulent suspensions where grain fall velocity is substantially reduced by hindered settling, and 3) pebble- and cobble-sized clasts having concentrations greater than 10 percent to 15 percent that will be supported largely by dispersive pressure resulting from clast collisions and by buoyant lift provided by the interstitial mixture of water and finer-grained sediment. The effects of hindered settling, dispersive pressure, and matrix buoyant lift are con entration dependent, and grain populations 2 and 3 are likely to be transported in large amounts only within flows having high particle concentrations, probably in excess of 20 percent solids by volume. Low-density turbidity currents, made up largely of grains of population 1, typically show an initial period of traction sedimentation, forming Bouma (Tb) and Tc) divisions, followed by one of mixed traction and suspension sedimentation (Td), and a terminal period of fine-grained suspension sedimentation (Te). The sediment loads of high-density turbidity currents commonly include grains belonging to populations 1, 2, and 3. Consequently, deposition often occurs as a series of discrete sedimentation waves as flows decelerate and individual grain populations can no longer be maintained in transport. Each sedimentation wave tends to show increasing unsteadiness and accelerating sedimentation rate as it evolves, passing from an initial stage of traction sedimentation, to one of mixed frictional freezing and suspension sedimentation within traction carpets, to a final stage of direct suspension sedimentation. Sequences of sedimentary structure divisions representing this succession of depositional stages are here termed the ecoR1-3) sequence, representing population 3 grains, and the S1-3) sequence, representing population 2. Deposition of the high-density suspended load leaves behind a residual low-density turbidity current composed largely of population 1 grains. At their distal ends, high-density turbidity currents deposit mainly by suspension sedimentation, forming thin (S3) divisions. These (S3) divisions are the same as Bouma (Ta) and, if subsequently capped by (Tb-e) deposited by the residual low-density flows, become the basal divisions of normal turbidities. Liquefied flows deposit by direct high-density suspension sedimentation. Grain flows of sand are characterized by frictional freezing and their deposits are limited mainly to angle-of-repose slipface units. Density-modified grain flows, in which larger clasts are partially supported by matrix buoyancy, and traction carpets, in which a dense frictional grain dispersion is driven by an overlying turbulent flow, are important in the buildup of natural deposits on submarine slopes. Cohesive debris flows depost sediment mainly by cohesive freezing, commonly modified by suspension sedimentation of the largest clasts.

@article{doi101306212f7f312b2411d78648000102c1865d,
    author = "Lowe, Donald R.",
    title = "Sediment Gravity Flows: II Depositional Models with Special Reference to the Deposits of High-Density Turbidity Currents",
    year = "1982",
    journal = "Journal of Sedimentary Research",
    abstract = "ABSTRACT Four principal mechanisms of deposition are effective in the formation of sediment gravity flow deposits. Grains deposited by traction sedimentation and suspension sedimentation respond individually and accumulate directly from bed and suspended loads, respectively. Those deposited by frictional freezing and cohesive freezing interact through either frictional contact or cohesive forces, respectively, and are deposited collectively, usually by plug formation. Sediment deposition from individual sediment flows commonly involves more than one of these mechanisms acting either serially as the flow evolves or simultaneously on different grain populations. Deposition from turbidity currents is treated in terms of three dynamic grain populations: 1) clay- to medium-grained sand-sized particles that can be fully suspended as individual grains by flow turbulence, 2) coarse-grained sand to small-pebble-sized gravel that can be fully suspended in large amounts mainly in highly concentrated turbulent suspensions where grain fall velocity is substantially reduced by hindered settling, and 3) pebble- and cobble-sized clasts having concentrations greater than 10 percent to 15 percent that will be supported largely by dispersive pressure resulting from clast collisions and by buoyant lift provided by the interstitial mixture of water and finer-grained sediment. The effects of hindered settling, dispersive pressure, and matrix buoyant lift are con entration dependent, and grain populations 2 and 3 are likely to be transported in large amounts only within flows having high particle concentrations, probably in excess of 20 percent solids by volume. Low-density turbidity currents, made up largely of grains of population 1, typically show an initial period of traction sedimentation, forming Bouma (Tb) and Tc) divisions, followed by one of mixed traction and suspension sedimentation (Td), and a terminal period of fine-grained suspension sedimentation (Te). The sediment loads of high-density turbidity currents commonly include grains belonging to populations 1, 2, and 3. Consequently, deposition often occurs as a series of discrete sedimentation waves as flows decelerate and individual grain populations can no longer be maintained in transport. Each sedimentation wave tends to show increasing unsteadiness and accelerating sedimentation rate as it evolves, passing from an initial stage of traction sedimentation, to one of mixed frictional freezing and suspension sedimentation within traction carpets, to a final stage of direct suspension sedimentation. Sequences of sedimentary structure divisions representing this succession of depositional stages are here termed the ecoR1-3) sequence, representing population 3 grains, and the S1-3) sequence, representing population 2. Deposition of the high-density suspended load leaves behind a residual low-density turbidity current composed largely of population 1 grains. At their distal ends, high-density turbidity currents deposit mainly by suspension sedimentation, forming thin (S3) divisions. These (S3) divisions are the same as Bouma (Ta) and, if subsequently capped by (Tb-e) deposited by the residual low-density flows, become the basal divisions of normal turbidities. Liquefied flows deposit by direct high-density suspension sedimentation. Grain flows of sand are characterized by frictional freezing and their deposits are limited mainly to angle-of-repose slipface units. Density-modified grain flows, in which larger clasts are partially supported by matrix buoyancy, and traction carpets, in which a dense frictional grain dispersion is driven by an overlying turbulent flow, are important in the buildup of natural deposits on submarine slopes. Cohesive debris flows depost sediment mainly by cohesive freezing, commonly modified by suspension sedimentation of the largest clasts.",
    url = "https://doi.org/10.1306/212f7f31-2b24-11d7-8648000102c1865d",
    doi = "10.1306/212f7f31-2b24-11d7-8648000102c1865d",
    openalex = "W2087125749"
}

Hydrothermal alteration associated with an Archean stratiform volcanogenic massive sulfide deposit has converted aphyric rhyodacite to chloritite. In addition to normal chlorite components (MgO, FeO, Al 2 O 3, SiO 2), the chloritite is enriched in TiO 2, Zr, Y, and Nb. These elements and Al 2 O 3 are shown to be immobile using binary plots of analyses which produce linear arrays, with high correlation coefficients, that go through bulk composition and origin. Al 2 O 3 is the most immobile, followed by Zr, Nb, TiO 2, and Y.Immobility requires that these elements became enriched by in situ residual concentration. This was caused mostly by initial wholesale leaching of silica--mainly quartz--followed by leaching of SiO 2 and Fe 2 O (super [whitesunwithrays]) 3 (total iron as Fe 2 O 3) from chlorite. Alteration of rhyodacite proceeded from an initial stage of silicification and chloritization (addition of MgO and Fe 2 O (super [whitesunwithrays]) 3) of glass and feldspar (loss of Na 2 O and CaO) to a stage of leaching of quartz wherein over 50 percent of the mass of the unit was lost. In the final stage, leaching of Fe 12 Si 8 O 20 (OH) 16 accounted for a further 10 percent loss, leaving Mg- and Al-rich chlorite as essentially the sole component of the chloritite rock.

@article{doi102113gsecongeo824951,
    author = "MacLean, W. H. and Kranidiotis, P.",
    title = "Immobile elements as monitors of mass transfer in hydrothermal alteration; Phelps Dodge massive sulfide deposit, Matagami, Quebec",
    year = "1987",
    journal = "Economic Geology",
    abstract = "Hydrothermal alteration associated with an Archean stratiform volcanogenic massive sulfide deposit has converted aphyric rhyodacite to chloritite. In addition to normal chlorite components (MgO, FeO, Al 2 O 3, SiO 2), the chloritite is enriched in TiO 2, Zr, Y, and Nb. These elements and Al 2 O 3 are shown to be immobile using binary plots of analyses which produce linear arrays, with high correlation coefficients, that go through bulk composition and origin. Al 2 O 3 is the most immobile, followed by Zr, Nb, TiO 2, and Y.Immobility requires that these elements became enriched by in situ residual concentration. This was caused mostly by initial wholesale leaching of silica--mainly quartz--followed by leaching of SiO 2 and Fe 2 O (super [whitesunwithrays]) 3 (total iron as Fe 2 O 3) from chlorite. Alteration of rhyodacite proceeded from an initial stage of silicification and chloritization (addition of MgO and Fe 2 O (super [whitesunwithrays]) 3) of glass and feldspar (loss of Na 2 O and CaO) to a stage of leaching of quartz wherein over 50 percent of the mass of the unit was lost. In the final stage, leaching of Fe 12 Si 8 O 20 (OH) 16 accounted for a further 10 percent loss, leaving Mg- and Al-rich chlorite as essentially the sole component of the chloritite rock.",
    url = "https://doi.org/10.2113/gsecongeo.82.4.951",
    doi = "10.2113/gsecongeo.82.4.951",
    openalex = "W2166873451"
}

@article{doi1010160012825289900020,
    author = "Caron, Christian and Homewood, Peter and Wildi, Walter",
    title = "The original Swiss flysch: a reappraisal of the type deposits in the Swiss prealps",
    year = "1989",
    journal = "Earth-Science Reviews",
    url = "https://doi.org/10.1016/0012-8252(89)90002-0",
    doi = "10.1016/0012-8252(89)90002-0",
    openalex = "W2003433354",
    references = "doi1010160012825283900016, doi1010160040195181902857, doi101029jb075i014p02625, doi101086625710, doi101126science23547931156, doi101306212f7f312b2411d78648000102c1865d, doi102973dsdpproc321151975, openalexw3120543430, openalexw574151162, openalexw586757543"
}

Numerical models that solve governing equations for subsurface fluid flow and transport are commonly applied to analyze quantitatively the effects of heterogeneity. These models require maps of spatially variable hydraulic properties. Because complete three‐dimensional information about hydraulic properties is never obtainable, numerous methods have been developed to interpolate between data values and use geologic, hydrogeologic, and geophysical information to create images of aquifer properties. Image creation approaches fall into three general categories: structure‐imitating, process‐imitating, and descriptive. Structure‐imitating methods rely on one or more of the following to constrain the geometry of spatial patterns in geologic media: correlated random fields, probabilistic rules, and deterministic constraints developed from facies relations. Structure‐imitating methods include spatial statistical algorithms and geologically based sedimentation pattern‐matching approaches. Process‐imitating models include aquifer model calibration methods and geologic process models. Aquifer model calibration methods use governing equations for subsurface fluid flow and transport to relate hydraulic properties to heads and solute information through history and steady state data matching. Geologic process models combine fundamental laws of conservation of mass and momentum with sediment transport equations to simulate spatial patterns in grain size distributions. At the sedimentary basin scale, multiprocess models include thermomechanical mechanisms of basin subsidence. Descriptive methods couple geologic observations with facies relations to divide an aquifer into zones of characteristic hydraulic properties. All approaches are capable of reproducing heterogeneity over a range of scales and considering some types of geologic information. Some approaches are strictly spatial while some are linked to the time evolution of sedimentation. Some approaches can be conditioned on measurements. Recent advances aimed at infusing geologic information into images of the subsurface include extracting more information from sedimentological facies models, incorporating qualitative geologic information into random field generators and simulating depositional processes. Classes of research missing from the literature include multiprocess models that incorporate diagenesis and three‐dimensional surface water flow, hybrid methods that combine features of existing approaches, and approaches that can make use of all available geologic, geophysical, and hydrologic data.

@article{doi10102996wr00025,
    author = "Koltermann, Christine E. and Gorelick, Steven M.",
    title = "Heterogeneity in Sedimentary Deposits: A Review of Structure‐Imitating, Process‐Imitating, and Descriptive Approaches",
    year = "1996",
    journal = "Water Resources Research",
    abstract = "Numerical models that solve governing equations for subsurface fluid flow and transport are commonly applied to analyze quantitatively the effects of heterogeneity. These models require maps of spatially variable hydraulic properties. Because complete three‐dimensional information about hydraulic properties is never obtainable, numerous methods have been developed to interpolate between data values and use geologic, hydrogeologic, and geophysical information to create images of aquifer properties. Image creation approaches fall into three general categories: structure‐imitating, process‐imitating, and descriptive. Structure‐imitating methods rely on one or more of the following to constrain the geometry of spatial patterns in geologic media: correlated random fields, probabilistic rules, and deterministic constraints developed from facies relations. Structure‐imitating methods include spatial statistical algorithms and geologically based sedimentation pattern‐matching approaches. Process‐imitating models include aquifer model calibration methods and geologic process models. Aquifer model calibration methods use governing equations for subsurface fluid flow and transport to relate hydraulic properties to heads and solute information through history and steady state data matching. Geologic process models combine fundamental laws of conservation of mass and momentum with sediment transport equations to simulate spatial patterns in grain size distributions. At the sedimentary basin scale, multiprocess models include thermomechanical mechanisms of basin subsidence. Descriptive methods couple geologic observations with facies relations to divide an aquifer into zones of characteristic hydraulic properties. All approaches are capable of reproducing heterogeneity over a range of scales and considering some types of geologic information. Some approaches are strictly spatial while some are linked to the time evolution of sedimentation. Some approaches can be conditioned on measurements. Recent advances aimed at infusing geologic information into images of the subsurface include extracting more information from sedimentological facies models, incorporating qualitative geologic information into random field generators and simulating depositional processes. Classes of research missing from the literature include multiprocess models that incorporate diagenesis and three‐dimensional surface water flow, hybrid methods that combine features of existing approaches, and approaches that can make use of all available geologic, geophysical, and hydrologic data.",
    url = "https://doi.org/10.1029/96wr00025",
    doi = "10.1029/96wr00025",
    openalex = "W2083583624",
    references = "doi10100797814612378841, doi1010079783642814983, doi1010160012825277900551, doi1010160012825285900017, doi1010160012825287900419, doi1010160037073878900027, doi101111j136530911965tb01561x, doi101111j136530911979tb00935x, doi10130603b599f416d111d78645000102c1865d, doi101306mth7510, doi102110pec88010039, doi1023073514634, doi105860choice295709"
}

ABSTRACT The effects of liquefaction in saturated sand bodies under a variety of driving forces are described from shaking table experiments, and structures from the geological record are presented which are analogous to the experimental structures. The collapse of sloping heaps of cross‐bedded sand under a gravitational body force generates low‐angle, essentially uncontorted stratification. A basal zone of shearing may be present, with steepened and folded foresets. Stretching of foresets may be accommodated on normal faults, and bottomsets may be contorted into inclined folds. In natural systems the substrate may also liquefy, causing deformation driven by an unevenly distributed confining load. Stratification in the surface bedform is flattened, and stratification in the substratum contorted. Experiments failed to produce relative displacement at the interface between stacked sand bodies. Liquefaction of gravitationally unstable systems in sands generates load structures comparable to those from sand‐mud systems. Recumbent‐folded deformed cross‐bedding is formed by current shear over a liquefied bed, as has been inferred from field and theoretical analyses. Shear of nonliquefied sand forms angular folds. Other deformation mechanisms, such as fluidization or seepage, may generate structures similar to all of these. Local water‐escape structures driven by fluidization occur in the upper parts of some liquefied sand bodies. They include cusps, sand volcanoes and clastic dykes. Transient cavities formed in some experiments and seemed to be preserved as breached cusps. Although the experiments tried to isolate individual driving forces, driving forces may operate together, and there may be a continuum between deformation driven by water escape and deformation driven by loading. Different structures from those described here may form where liquefaction develops in a buried layer as opposed to at the sediment surface.

@article{doi101046j136530911996d015x,
    author = "Owen, Geraint",
    title = "Experimental soft‐sediment deformation: structures formed by the liquefaction of unconsolidated sands and some ancient examples",
    year = "1996",
    journal = "Sedimentology",
    abstract = "ABSTRACT The effects of liquefaction in saturated sand bodies under a variety of driving forces are described from shaking table experiments, and structures from the geological record are presented which are analogous to the experimental structures. The collapse of sloping heaps of cross‐bedded sand under a gravitational body force generates low‐angle, essentially uncontorted stratification. A basal zone of shearing may be present, with steepened and folded foresets. Stretching of foresets may be accommodated on normal faults, and bottomsets may be contorted into inclined folds. In natural systems the substrate may also liquefy, causing deformation driven by an unevenly distributed confining load. Stratification in the surface bedform is flattened, and stratification in the substratum contorted. Experiments failed to produce relative displacement at the interface between stacked sand bodies. Liquefaction of gravitationally unstable systems in sands generates load structures comparable to those from sand‐mud systems. Recumbent‐folded deformed cross‐bedding is formed by current shear over a liquefied bed, as has been inferred from field and theoretical analyses. Shear of nonliquefied sand forms angular folds. Other deformation mechanisms, such as fluidization or seepage, may generate structures similar to all of these. Local water‐escape structures driven by fluidization occur in the upper parts of some liquefied sand bodies. They include cusps, sand volcanoes and clastic dykes. Transient cavities formed in some experiments and seemed to be preserved as breached cusps. Although the experiments tried to isolate individual driving forces, driving forces may operate together, and there may be a continuum between deformation driven by water escape and deformation driven by loading. Different structures from those described here may form where liquefaction develops in a buried layer as opposed to at the sediment surface.",
    url = "https://doi.org/10.1046/j.1365-3091.1996.d01-5.x",
    doi = "10.1046/j.1365-3091.1996.d01-5.x",
    openalex = "W2171167339",
    references = "doi1010160012825283900223, doi101111j136530911975tb00290x, doi101111j136530911976tb00051x"
}

Summary The literature on the structure and behaviour of gravity currents is reviewed, with emphasis on some recent studies, and with particular attention to turbidity currents, though reference is also made to comparable behaviour in pyroclastic flows. Questions of definition are discussed, in particular the distinction between dense currents, which may deposit en masse, and more dilute currents. High‐density dispersions may exist as a discrete, independently moving layer beneath a more dilute flow, as the basal part of a continuous density distribution or possibly as a transient depositional layer. Existing theory appears inadequate to explain the behaviour of some high‐density dispersions. Surge‐type currents are contrasted with quasi‐steady currents, which may be generated by a variety of mechanisms including direct feed by rivers in flood. Such fluvially generated currents provide one means of generating currents with reversing buoyancy. Geologically significant turbidity currents are impractical for direct study owing to their large scale and (often) destructive nature. Small‐scale laboratory currents offer a wealth of insights into turbidity current behaviour. This paper summarizes recent experimental studies that focus on the physical structure of gravity currents, with emphasis on the velocity and turbulence structure, the vertical density distribution and the stability of stratification. Preliminary quantification of the turbulence structure (including controls on turbulent entrainment, turbulent kinetic energy, Reynolds stresses and turbulence production) has been facilitated by recent technological developments that have allowed the measurement of instantaneous fluctuations in both velocity and concentration. Laboratory models, however, generally involve substantial simplification, and require compromises in some parameters to achieve adequate scaling of the parameters of most interest. Mathematical modelling also provides important insights into turbidity current behaviour. We discuss various approaches to modelling, ranging from simple hydraulic equations to systems of partial differential equations that explicitly treat conservation of momentum, fluid and sediment mass, and turbulent kinetic energy. The application for which the model is designed (i.e. to calculate mean head velocity or to create an instantaneous two‐dimensional contour plot of downstream velocity in a current) determines the complexity of the mathematical model required. The behaviour of suspension currents around topography is complex and depends upon the relative height of the topography, and upon the density and velocity structure of the current. Many interactions with topography are well described by the internal Froude number, Fr i. Both reflection and deflection of currents may occur on the upstream side of topography, depending upon Fr i. On the downstream side of topography, flow separation, lee waves or hydraulic jumps may occur.

@article{doi101046j136530912000047s1062x,
    author = "Kneller, Ben and Buckee, Clare",
    title = "The structure and fluid mechanics of turbidity currents: a review of some recent studies and their geological implications",
    year = "2000",
    journal = "Sedimentology",
    abstract = "Summary The literature on the structure and behaviour of gravity currents is reviewed, with emphasis on some recent studies, and with particular attention to turbidity currents, though reference is also made to comparable behaviour in pyroclastic flows. Questions of definition are discussed, in particular the distinction between dense currents, which may deposit en masse, and more dilute currents. High‐density dispersions may exist as a discrete, independently moving layer beneath a more dilute flow, as the basal part of a continuous density distribution or possibly as a transient depositional layer. Existing theory appears inadequate to explain the behaviour of some high‐density dispersions. Surge‐type currents are contrasted with quasi‐steady currents, which may be generated by a variety of mechanisms including direct feed by rivers in flood. Such fluvially generated currents provide one means of generating currents with reversing buoyancy. Geologically significant turbidity currents are impractical for direct study owing to their large scale and (often) destructive nature. Small‐scale laboratory currents offer a wealth of insights into turbidity current behaviour. This paper summarizes recent experimental studies that focus on the physical structure of gravity currents, with emphasis on the velocity and turbulence structure, the vertical density distribution and the stability of stratification. Preliminary quantification of the turbulence structure (including controls on turbulent entrainment, turbulent kinetic energy, Reynolds stresses and turbulence production) has been facilitated by recent technological developments that have allowed the measurement of instantaneous fluctuations in both velocity and concentration. Laboratory models, however, generally involve substantial simplification, and require compromises in some parameters to achieve adequate scaling of the parameters of most interest. Mathematical modelling also provides important insights into turbidity current behaviour. We discuss various approaches to modelling, ranging from simple hydraulic equations to systems of partial differential equations that explicitly treat conservation of momentum, fluid and sediment mass, and turbulent kinetic energy. The application for which the model is designed (i.e. to calculate mean head velocity or to create an instantaneous two‐dimensional contour plot of downstream velocity in a current) determines the complexity of the mathematical model required. The behaviour of suspension currents around topography is complex and depends upon the relative height of the topography, and upon the density and velocity structure of the current. Many interactions with topography are well described by the internal Froude number, Fr i. Both reflection and deflection of currents may occur on the upstream side of topography, depending upon Fr i. On the downstream side of topography, flow separation, lee waves or hydraulic jumps may occur.",
    url = "https://doi.org/10.1046/j.1365-3091.2000.047s1062.x",
    doi = "10.1046/j.1365-3091.2000.047s1062.x",
    openalex = "W1587200101",
    references = "dejong1972flysch, doi10100797814684827682, doi10100797814684827684, doi1010160012825275900987, doi1010160012825283900223, doi1010160025322764900489, doi101016b9780124822504x50012, doi101017s0022112059000738, doi101029rg020i004p00851, doi101086625710, doi101086629747, doi1013061d9bc5d9172d11d78645000102c1865d, doi101306212f7f312b2411d78648000102c1865d, doi101306bdff8e16171811d78645000102c1865d, doi1023071794727, doi107551mitpress30140010001, openalexw2540891886, openalexw3128664696, openalexw3166868886"
}

The complexity of flow and wide variety of depositional processes operating in subaqueous density flows, combined with post‐depositional consolidation and soft‐sediment deformation, often make it difficult to interpret the characteristics of the original flow from the sedimentary record. This has led to considerable confusion of nomenclature in the literature. This paper attempts to clarify this situation by presenting a simple classification of sedimentary density flows, based on physical flow properties and grain‐support mechanisms, and briefly discusses the likely characteristics of the deposited sediments. Cohesive flows are commonly referred to as debris flows and mud flows and defined on the basis of sediment characteristics. The boundary between cohesive and non‐cohesive density flows (frictional flows) is poorly constrained, but dimensionless numbers may be of use to define flow thresholds. Frictional flows include a continuous series from sediment slides to turbidity currents. Subdivision of these flows is made on the basis of the dominant particle‐support mechanisms, which include matrix strength (in cohesive flows), buoyancy, pore pressure, grain‐to‐grain interaction (causing dispersive pressure), Reynolds stresses (turbulence) and bed support (particles moved on the stationary bed). The dominant particle‐support mechanism depends upon flow conditions, particle concentration, grain‐size distribution and particle type. In hyperconcentrated density flows, very high sediment concentrations (>25 volume%) make particle interactions of major importance. The difference between hyperconcentrated density flows and cohesive flows is that the former are friction dominated. With decreasing sediment concentration, vertical particle sorting can result from differential settling, and flows in which this can occur are termed concentrated density flows. The boundary between hyperconcentrated and concentrated density flows is defined by a change in particle behaviour, such that denser or larger grains are no longer fully supported by grain interaction, thus allowing coarse‐grain tail (or dense‐grain tail) normal grading. The concentration at which this change occurs depends on particle size, sorting, composition and relative density, so that a single threshold concentration cannot be defined. Concentrated density flows may be highly erosive and subsequently deposit complete or incomplete Lowe and Bouma sequences. Conversely, hydroplaning at the base of debris flows, and possibly also in some hyperconcentrated flows, may reduce the fluid drag, thus allowing high flow velocities while preventing large‐scale erosion. Flows with concentrations <9% by volume are true turbidity flows (sensu Bagnold, 1962), in which fluid turbulence is the main particle‐support mechanism. Turbidity flows and concentrated density flows can be subdivided on the basis of flow duration into instantaneous surges, longer duration surge‐like flows and quasi‐steady currents. Flow duration is shown to control the nature of the resulting deposits. Surge‐like turbidity currents tend to produce classical Bouma sequences, whose nature at any one site depends on factors such as flow size, sediment type and proximity to source. In contrast, quasi‐steady turbidity currents, generated by hyperpycnal river effluent, can deposit coarsening‐up units capped by fining‐up units (because of waxing and waning conditions respectively) and may also include thick units of uniform character (resulting from prolonged periods of near‐steady conditions). Any flow type may progressively change character along the transport path, with transformation primarily resulting from reductions in sediment concentration through progressive entrainment of surrounding fluid and/or sediment deposition. The rate of fluid entrainment, and consequently flow transformation, is dependent on factors including slope gradient, lateral confinement, bed roughness, flow thickness and water depth. Flows with high and low sediment concentrations may co‐exist in one transport event because of downflow transformations, flow stratification or shear layer development of the mixing interface with the overlying water (mixing cloud formation). Deposits of an individual flow event at one site may therefore form from a succession of different flow types, and this introduces considerable complexity into classifying the flow event or component flow types from the deposits.

@article{doi101046j13653091200100360x,
    author = "Mulder, Thierry and Alexander, Jan",
    title = "The physical character of subaqueous sedimentary density flows and their deposits",
    year = "2001",
    journal = "Sedimentology",
    abstract = "The complexity of flow and wide variety of depositional processes operating in subaqueous density flows, combined with post‐depositional consolidation and soft‐sediment deformation, often make it difficult to interpret the characteristics of the original flow from the sedimentary record. This has led to considerable confusion of nomenclature in the literature. This paper attempts to clarify this situation by presenting a simple classification of sedimentary density flows, based on physical flow properties and grain‐support mechanisms, and briefly discusses the likely characteristics of the deposited sediments. Cohesive flows are commonly referred to as debris flows and mud flows and defined on the basis of sediment characteristics. The boundary between cohesive and non‐cohesive density flows (frictional flows) is poorly constrained, but dimensionless numbers may be of use to define flow thresholds. Frictional flows include a continuous series from sediment slides to turbidity currents. Subdivision of these flows is made on the basis of the dominant particle‐support mechanisms, which include matrix strength (in cohesive flows), buoyancy, pore pressure, grain‐to‐grain interaction (causing dispersive pressure), Reynolds stresses (turbulence) and bed support (particles moved on the stationary bed). The dominant particle‐support mechanism depends upon flow conditions, particle concentration, grain‐size distribution and particle type. In hyperconcentrated density flows, very high sediment concentrations (>25 volume\%) make particle interactions of major importance. The difference between hyperconcentrated density flows and cohesive flows is that the former are friction dominated. With decreasing sediment concentration, vertical particle sorting can result from differential settling, and flows in which this can occur are termed concentrated density flows. The boundary between hyperconcentrated and concentrated density flows is defined by a change in particle behaviour, such that denser or larger grains are no longer fully supported by grain interaction, thus allowing coarse‐grain tail (or dense‐grain tail) normal grading. The concentration at which this change occurs depends on particle size, sorting, composition and relative density, so that a single threshold concentration cannot be defined. Concentrated density flows may be highly erosive and subsequently deposit complete or incomplete Lowe and Bouma sequences. Conversely, hydroplaning at the base of debris flows, and possibly also in some hyperconcentrated flows, may reduce the fluid drag, thus allowing high flow velocities while preventing large‐scale erosion. Flows with concentrations <9\% by volume are true turbidity flows (sensu Bagnold, 1962), in which fluid turbulence is the main particle‐support mechanism. Turbidity flows and concentrated density flows can be subdivided on the basis of flow duration into instantaneous surges, longer duration surge‐like flows and quasi‐steady currents. Flow duration is shown to control the nature of the resulting deposits. Surge‐like turbidity currents tend to produce classical Bouma sequences, whose nature at any one site depends on factors such as flow size, sediment type and proximity to source. In contrast, quasi‐steady turbidity currents, generated by hyperpycnal river effluent, can deposit coarsening‐up units capped by fining‐up units (because of waxing and waning conditions respectively) and may also include thick units of uniform character (resulting from prolonged periods of near‐steady conditions). Any flow type may progressively change character along the transport path, with transformation primarily resulting from reductions in sediment concentration through progressive entrainment of surrounding fluid and/or sediment deposition. The rate of fluid entrainment, and consequently flow transformation, is dependent on factors including slope gradient, lateral confinement, bed roughness, flow thickness and water depth. Flows with high and low sediment concentrations may co‐exist in one transport event because of downflow transformations, flow stratification or shear layer development of the mixing interface with the overlying water (mixing cloud formation). Deposits of an individual flow event at one site may therefore form from a succession of different flow types, and this introduces considerable complexity into classifying the flow event or component flow types from the deposits.",
    url = "https://doi.org/10.1046/j.1365-3091.2001.00360.x",
    doi = "10.1046/j.1365-3091.2001.00360.x",
    openalex = "W2120162798",
    references = "doi101007bf00301484, doi101016s0012825297818582, doi101017s0022112089000340, doi10102997rg00426, doi101046j136530912000047s1062x, doi101086626171, doi101086627725, doi101086629747, doi101098rspa19540186, doi101111j136530911983tb00702x, doi101130reg7p1, doi101146annurevearth25185, doi101306212f7f312b2411d78648000102c1865d, doi1013065ceadd7616bb11d78645000102c1865d, doi1013065d25cc7916c111d78645000102c1865d, doi10130674d723b52b2111d78648000102c1865d, doi10130674d7262b2b2111d78648000102c1865d, doi102110scn8403, doi102475ajs25012849, nardin1979a, normark1978fan, openalexw1570283708"
}

Abstract The concept of turbidite has evolved so much since its original definition by Kuenen and Migliorini in 1950 – i.e. the deposit of turbidity currents exemplified by the sandy flysch successions of the Northern Apennines – that it is now used to define a variety of deposits, some of which have little in common with sandy flysch formations in terms of facies, geometry and geological significance. The extension of the concept to other geodynamic settings and deposits of non‐siliciclastic composition is considered only briefly in the concluding sections. With the diffusion of the concept of turbidity current, in the 1950s and early 1960s, an entirely new branch of sedimentology came into being, concerned with the inventory of sedimentary structures, palaeocurrent measurements and bedding patterns. The most representative expression of this branch came from the ‘Dutch school’ of Philip H. Kuenen and his students. Between the late 1960s and the mid‐1970s, there was a new development: facies analysis, in terms of modern environments and depositional systems. This development led to the introduction and discussion of ‘fan models’ that became an increasingly thorny issue with the accumulation of data from modern deep‐marine settings. In particular, most researchers emphasized the importance of channel and lobe elements and their mutual relationships in space and time. These models may differ in terms of specific features, e.g. canyon‐fed versus delta‐fed ramp settings and terminology, but the basic distinction between channels (sediment pathways), lobes and basin plains (sheet‐like depositional features) was and still is widely retained – a model that simply refers to a system where a distributary channel passes downstream to a depositional zone, like in most fluvio‐deltaic systems. Great caution should, however, be exercised when comparing modern and ancient fans – a problem discussed at length in the Committee on Submarine Fans I convened by A.H. Bouma and held in Pittsburgh in 1982. Different data sets and geological contexts, scaling problems and terminology still cast doubt over how meaningful such a comparison may be. Despite the many problems encountered, the elemental approach provides an easy, essentially descriptive tool to significantly compare recent with ancient, recent with recent, and ancient with ancient systems. Beginning in the 1970s, process‐oriented facies analysis led to increasingly complex facies classification schemes, which showed substantial departures from the classic Bouma sequence and introduced many new concepts: proximal versus distal sedimentation, sediment bypass and flow efficiency, in addition to deflection, reflection and ponding of turbidity currents in confined basins. During the last two decades, there has been an increased interest in attempting to interpret the incredibly detailed submarine landscapes obtained through advances in marine geology, technology and high‐resolution three‐dimensional seismic data provided by the oil industry. Outcrop ‘analogues’ derived from orogenic belts are used commonly to improve the interpretation of seismic‐reflection facies, although their actual value may be questioned in many cases. Seismic–stratigraphic concepts are used routinely to describe and interpret turbidite systems of continental margin basins where cyclic sea‐level variations are thought to be essentially controlled by eustasy. These concepts are difficult to apply to flysch basins, where the tectonic control on the development of cycles of relative sea‐level variations appears to be dominant. In particular, the huge volumes of sediment involved in the infill of flysch basins imply amounts of uplift of the source areas and subsidence of the receiving basins that clearly outstrip those of divergent continental margins controlled by eustasy and thermal subsidence. Cycles of tectonic uplift and denudation (Davisian‐type cycles in the sense of Mutti et al., 1996) apparently play a major role here. Most recent attempts to understand turbidite deposition are related to the increased economic importance of turbidite sandbodies as hydrocarbon reservoirs in many offshore basins (e.g. Gulf of Mexico, West Africa, Brazil, the North Sea). The many problems inherent to this situation have been reviewed extensively in a workshop held in Parma in 2002; only some of these problems are reconsidered briefly in this paper. Sandy turbidite systems can be generated by the resedimentation of deltaic deposits through submarine slides or be derived directly from flood‐generated hyperpycnal flows; in the latter case, climatic variations must have played a fundamental role in controlling flood frequency and magnitude with time. Recognizing these two different types of system is not always easy and requires a good understanding of the geological context of the basin under consideration and particularly of the role of marginal fluvio‐deltaic systems from which turbidites are ultimately derived. Unfortunately, this kind of integrated analysis is still in its infancy. There are other types of turbidite deposits, such as the calcareous flysch of the Western Alps and the Northern Apennines, whose origin still remains a matter of debate in terms of sediment source and triggering mechanisms of large‐volume turbidity currents essentially loaded with fine‐grained biogenic sediment. Some authors have referred to these sediments either as ‘megaturbidites’ or ‘seismoturbidites’. The importance of tectonic control and geodynamic setting is stressed for turbidite systems of orogenic belt basins, which is justified both by historical reasons (turbidites were from their recognition included in the definition of flysch) and recent studies of thrust belts. The time is now ripe for reconsidering these sediments within a broader framework that takes into account the enormous quantity of data and concepts that have been developed in the last 50 years; this in itself raises a problem, and no small one: the accuracy and quality of data collected in the field and the training of young scientists. How many field geologists are being produced in these times of increasingly computerized geology; and how good are they?

@article{doi101111j13653091200801019x,
    author = "Mutti, Emiliano and Bernoulli, Daniel and Lucchi, Franco Ricci and Tinterri, Roberto",
    title = "Turbidites and turbidity currents from Alpine ‘flysch’ to the exploration of continental margins",
    year = "2008",
    journal = "Sedimentology",
    abstract = "Abstract The concept of turbidite has evolved so much since its original definition by Kuenen and Migliorini in 1950 – i.e. the deposit of turbidity currents exemplified by the sandy flysch successions of the Northern Apennines – that it is now used to define a variety of deposits, some of which have little in common with sandy flysch formations in terms of facies, geometry and geological significance. The extension of the concept to other geodynamic settings and deposits of non‐siliciclastic composition is considered only briefly in the concluding sections. With the diffusion of the concept of turbidity current, in the 1950s and early 1960s, an entirely new branch of sedimentology came into being, concerned with the inventory of sedimentary structures, palaeocurrent measurements and bedding patterns. The most representative expression of this branch came from the ‘Dutch school’ of Philip H. Kuenen and his students. Between the late 1960s and the mid‐1970s, there was a new development: facies analysis, in terms of modern environments and depositional systems. This development led to the introduction and discussion of ‘fan models’ that became an increasingly thorny issue with the accumulation of data from modern deep‐marine settings. In particular, most researchers emphasized the importance of channel and lobe elements and their mutual relationships in space and time. These models may differ in terms of specific features, e.g. canyon‐fed versus delta‐fed ramp settings and terminology, but the basic distinction between channels (sediment pathways), lobes and basin plains (sheet‐like depositional features) was and still is widely retained – a model that simply refers to a system where a distributary channel passes downstream to a depositional zone, like in most fluvio‐deltaic systems. Great caution should, however, be exercised when comparing modern and ancient fans – a problem discussed at length in the Committee on Submarine Fans I convened by A.H. Bouma and held in Pittsburgh in 1982. Different data sets and geological contexts, scaling problems and terminology still cast doubt over how meaningful such a comparison may be. Despite the many problems encountered, the elemental approach provides an easy, essentially descriptive tool to significantly compare recent with ancient, recent with recent, and ancient with ancient systems. Beginning in the 1970s, process‐oriented facies analysis led to increasingly complex facies classification schemes, which showed substantial departures from the classic Bouma sequence and introduced many new concepts: proximal versus distal sedimentation, sediment bypass and flow efficiency, in addition to deflection, reflection and ponding of turbidity currents in confined basins. During the last two decades, there has been an increased interest in attempting to interpret the incredibly detailed submarine landscapes obtained through advances in marine geology, technology and high‐resolution three‐dimensional seismic data provided by the oil industry. Outcrop ‘analogues’ derived from orogenic belts are used commonly to improve the interpretation of seismic‐reflection facies, although their actual value may be questioned in many cases. Seismic–stratigraphic concepts are used routinely to describe and interpret turbidite systems of continental margin basins where cyclic sea‐level variations are thought to be essentially controlled by eustasy. These concepts are difficult to apply to flysch basins, where the tectonic control on the development of cycles of relative sea‐level variations appears to be dominant. In particular, the huge volumes of sediment involved in the infill of flysch basins imply amounts of uplift of the source areas and subsidence of the receiving basins that clearly outstrip those of divergent continental margins controlled by eustasy and thermal subsidence. Cycles of tectonic uplift and denudation (Davisian‐type cycles in the sense of Mutti et al., 1996) apparently play a major role here. Most recent attempts to understand turbidite deposition are related to the increased economic importance of turbidite sandbodies as hydrocarbon reservoirs in many offshore basins (e.g. Gulf of Mexico, West Africa, Brazil, the North Sea). The many problems inherent to this situation have been reviewed extensively in a workshop held in Parma in 2002; only some of these problems are reconsidered briefly in this paper. Sandy turbidite systems can be generated by the resedimentation of deltaic deposits through submarine slides or be derived directly from flood‐generated hyperpycnal flows; in the latter case, climatic variations must have played a fundamental role in controlling flood frequency and magnitude with time. Recognizing these two different types of system is not always easy and requires a good understanding of the geological context of the basin under consideration and particularly of the role of marginal fluvio‐deltaic systems from which turbidites are ultimately derived. Unfortunately, this kind of integrated analysis is still in its infancy. There are other types of turbidite deposits, such as the calcareous flysch of the Western Alps and the Northern Apennines, whose origin still remains a matter of debate in terms of sediment source and triggering mechanisms of large‐volume turbidity currents essentially loaded with fine‐grained biogenic sediment. Some authors have referred to these sediments either as ‘megaturbidites’ or ‘seismoturbidites’. The importance of tectonic control and geodynamic setting is stressed for turbidite systems of orogenic belt basins, which is justified both by historical reasons (turbidites were from their recognition included in the definition of flysch) and recent studies of thrust belts. The time is now ripe for reconsidering these sediments within a broader framework that takes into account the enormous quantity of data and concepts that have been developed in the last 50 years; this in itself raises a problem, and no small one: the accuracy and quality of data collected in the field and the training of young scientists. How many field geologists are being produced in these times of increasingly computerized geology; and how good are they?",
    url = "https://doi.org/10.1111/j.1365-3091.2008.01019.x",
    doi = "10.1111/j.1365-3091.2008.01019.x",
    openalex = "W2126274779",
    references = "doi1010160012825286900012, doi1010160012825289900020, doi101016jmargeo200410001, doi101016jmarpetgeo200309001, doi101016s0070457108709543, doi10102995rg03287, doi101086629606, doi101086629747, doi101111j13653091200801016x, doi101130001676061959701089tifotp20co2, doi101306212f7f312b2411d78648000102c1865d, doi101306mth7510, doi102110pec88010039, doi102110pec88010109, doi105860choice295709, openalexw1570283708, openalexw3160761443"
}

Abstract Sea floor and shallow seismic data sets of terminal submarine fan lobes can provide excellent planform timeslices of distributive deep‐water systems but commonly only limited information on cross‐sectional architecture. Extensive outcrops in the Tanqua depocentre, south‐west Karoo Basin, provide these three‐dimensional constraints on lithofacies distributions, stacking patterns, depositional geometries and the stratigraphic evolution of submarine lobe deposits at a scale comparable with modern lobe systems. Detailed study (bed‐scale) of a single‐lobe complex (Fan 3) over a 15 km by 8 km area has helped to define a four‐fold hierarchy of depositional elements from bed through to lobe element, lobe and lobe complex. The Fan 3 lobe complex comprises six distinct fine‐grained sandstone packages, interpreted as lobes, which display compensational stacking patterns on a 5 km scale. Between successive lobes are thin‐bedded, very fine‐grained sandstones and siltstones that do not change lithofacies over several kilometres and therefore are identified as a different architectural element. Each lobe is built by many lobe elements, which also display compensational stacking patterns over a kilometre scale. Thickness variations of lobe elements can be extremely abrupt without erosion, particularly in distal areas where isopach maps reveal a finger‐like distal fringe to lobes. Lobe deposits, therefore, are not simple radial sheet‐dominated systems as commonly envisaged.

@article{doi101111j13653091200901073x,
    author = "Prélat, Amandine and Hodgson, David M. and Flint, Stephen S.",
    title = "Evolution, architecture and hierarchy of distributary deep‐water deposits: a high‐resolution outcrop investigation from the Permian Karoo Basin, South Africa",
    year = "2009",
    journal = "Sedimentology",
    abstract = "Abstract Sea floor and shallow seismic data sets of terminal submarine fan lobes can provide excellent planform timeslices of distributive deep‐water systems but commonly only limited information on cross‐sectional architecture. Extensive outcrops in the Tanqua depocentre, south‐west Karoo Basin, provide these three‐dimensional constraints on lithofacies distributions, stacking patterns, depositional geometries and the stratigraphic evolution of submarine lobe deposits at a scale comparable with modern lobe systems. Detailed study (bed‐scale) of a single‐lobe complex (Fan 3) over a 15 km by 8 km area has helped to define a four‐fold hierarchy of depositional elements from bed through to lobe element, lobe and lobe complex. The Fan 3 lobe complex comprises six distinct fine‐grained sandstone packages, interpreted as lobes, which display compensational stacking patterns on a 5 km scale. Between successive lobes are thin‐bedded, very fine‐grained sandstones and siltstones that do not change lithofacies over several kilometres and therefore are identified as a different architectural element. Each lobe is built by many lobe elements, which also display compensational stacking patterns over a kilometre scale. Thickness variations of lobe elements can be extremely abrupt without erosion, particularly in distal areas where isopach maps reveal a finger‐like distal fringe to lobes. Lobe deposits, therefore, are not simple radial sheet‐dominated systems as commonly envisaged.",
    url = "https://doi.org/10.1111/j.1365-3091.2009.01073.x",
    doi = "10.1111/j.1365-3091.2009.01073.x",
    openalex = "W1977385910",
    references = "doi10100797814684827684, doi10100797894009324181, doi101016s0264817299000112, doi101016s0264817299000641, doi101046j13653091200300560x, doi101111j136530911977tb00126x, doi101111j13653091200700926x, doi101306111302730367, doi101306212f7f312b2411d78648000102c1865d, doi1013062f9182e316ce11d78645000102c1865d, doi1013065d25cc7916c111d78645000102c1865d, normark1978fan, posamentier2011deepwater"
}

Abstract Submarine sediment density flows are one of the most important processes for moving sediment across our planet, yet they are extremely difficult to monitor directly. The speed of long run‐out submarine density flows has been measured directly in just five locations worldwide and their sediment concentration has never been measured directly. The only record of most density flows is their sediment deposit. This article summarizes the processes by which density flows deposit sediment and proposes a new single classification for the resulting types of deposit. Colloidal properties of fine cohesive mud ensure that mud deposition is complex, and large volumes of mud can sometimes pond or drain‐back for long distances into basinal lows. Deposition of ungraded mud (T E‐3) most probably finally results from en masse consolidation in relatively thin and dense flows, although initial size sorting of mud indicates earlier stages of dilute and expanded flow. Graded mud (T E‐2) and finely laminated mud (T E‐1) most probably result from floc settling at lower mud concentrations. Grain‐size breaks beneath mud intervals are commonplace, and record bypass of intermediate grain sizes due to colloidal mud behaviour. Planar‐laminated (T D) and ripple cross‐laminated (T C) non‐cohesive silt or fine sand is deposited by dilute flow, and the external deposit shape is consistent with previous models of spatial decelerating (dissipative) dilute flow. A grain‐size break beneath the ripple cross‐laminated (T C) interval is common, and records a period of sediment reworking (sometimes into dunes) or bypass. Finely planar‐laminated sand can be deposited by low‐amplitude bed waves in dilute flow (T B‐1), but it is most likely to be deposited mainly by high‐concentration near‐bed layers beneath high‐density flows (T B‐2). More widely spaced planar lamination (T B‐3) occurs beneath massive clean sand (T A), and is also formed by high‐density turbidity currents. High‐density turbidite deposits (T A, T B‐2 and T B‐3) have a tabular shape consistent with hindered settling, and are typically overlain by a more extensive drape of low‐density turbidite (T D and T C,). This core and drape shape suggests that events sometimes comprise two distinct flow components. Massive clean sand is less commonly deposited en masse by liquefied debris flow (D CS), in which case the clean sand is ungraded or has a patchy grain‐size texture. Clean‐sand debrites can extend for several tens of kilometres before pinching out abruptly. Up‐current transitions suggest that clean‐sand debris flows sometimes form via transformation from high‐density turbidity currents. Cohesive debris flows can deposit three types of ungraded muddy sand that may contain clasts. Thick cohesive debrites tend to occur in more proximal settings and extend from an initial slope failure. Thinner and highly mobile low‐strength cohesive debris flows produce extensive deposits restricted to distal areas. These low‐strength debris flows may contain clasts and travel long distances (D M‐2), or result from more local flow transformation due to turbulence damping by cohesive mud (D M‐1). Mapping of individual flow deposits (beds) emphasizes how a single event can contain several flow types, with transformations between flow types. Flow transformation may be from dilute to dense flow, as well as from dense to dilute flow. Flow state, deposit type and flow transformation are strongly dependent on the volume fraction of cohesive fine mud within a flow. Recent field observations show significant deviations from previous widely cited models, and many hypotheses linking flow type to deposit type are poorly tested. There is much still to learn about these remarkable flows.

@article{doi101111j13653091201201353x,
    author = "Talling, Peter J. and Masson, Douglas G. and Sumner, E. J. and Malgesini, G.",
    title = "Subaqueous sediment density flows: Depositional processes and deposit types",
    year = "2012",
    journal = "Sedimentology",
    abstract = "Abstract Submarine sediment density flows are one of the most important processes for moving sediment across our planet, yet they are extremely difficult to monitor directly. The speed of long run‐out submarine density flows has been measured directly in just five locations worldwide and their sediment concentration has never been measured directly. The only record of most density flows is their sediment deposit. This article summarizes the processes by which density flows deposit sediment and proposes a new single classification for the resulting types of deposit. Colloidal properties of fine cohesive mud ensure that mud deposition is complex, and large volumes of mud can sometimes pond or drain‐back for long distances into basinal lows. Deposition of ungraded mud (T E‐3) most probably finally results from en masse consolidation in relatively thin and dense flows, although initial size sorting of mud indicates earlier stages of dilute and expanded flow. Graded mud (T E‐2) and finely laminated mud (T E‐1) most probably result from floc settling at lower mud concentrations. Grain‐size breaks beneath mud intervals are commonplace, and record bypass of intermediate grain sizes due to colloidal mud behaviour. Planar‐laminated (T D) and ripple cross‐laminated (T C) non‐cohesive silt or fine sand is deposited by dilute flow, and the external deposit shape is consistent with previous models of spatial decelerating (dissipative) dilute flow. A grain‐size break beneath the ripple cross‐laminated (T C) interval is common, and records a period of sediment reworking (sometimes into dunes) or bypass. Finely planar‐laminated sand can be deposited by low‐amplitude bed waves in dilute flow (T B‐1), but it is most likely to be deposited mainly by high‐concentration near‐bed layers beneath high‐density flows (T B‐2). More widely spaced planar lamination (T B‐3) occurs beneath massive clean sand (T A), and is also formed by high‐density turbidity currents. High‐density turbidite deposits (T A, T B‐2 and T B‐3) have a tabular shape consistent with hindered settling, and are typically overlain by a more extensive drape of low‐density turbidite (T D and T C,). This core and drape shape suggests that events sometimes comprise two distinct flow components. Massive clean sand is less commonly deposited en masse by liquefied debris flow (D CS), in which case the clean sand is ungraded or has a patchy grain‐size texture. Clean‐sand debrites can extend for several tens of kilometres before pinching out abruptly. Up‐current transitions suggest that clean‐sand debris flows sometimes form via transformation from high‐density turbidity currents. Cohesive debris flows can deposit three types of ungraded muddy sand that may contain clasts. Thick cohesive debrites tend to occur in more proximal settings and extend from an initial slope failure. Thinner and highly mobile low‐strength cohesive debris flows produce extensive deposits restricted to distal areas. These low‐strength debris flows may contain clasts and travel long distances (D M‐2), or result from more local flow transformation due to turbulence damping by cohesive mud (D M‐1). Mapping of individual flow deposits (beds) emphasizes how a single event can contain several flow types, with transformations between flow types. Flow transformation may be from dilute to dense flow, as well as from dense to dilute flow. Flow state, deposit type and flow transformation are strongly dependent on the volume fraction of cohesive fine mud within a flow. Recent field observations show significant deviations from previous widely cited models, and many hypotheses linking flow type to deposit type are poorly tested. There is much still to learn about these remarkable flows.",
    url = "https://doi.org/10.1111/j.1365-3091.2012.01353.x",
    doi = "10.1111/j.1365-3091.2012.01353.x",
    openalex = "W1934469433",
    references = "dejong1972flysch, doi1010160012825283900223, doi1010160037073880900524, doi1010160040195171900382, doi101016jmarpetgeo200301003, doi101016jmarpetgeo200309001, doi101016jmarpetgeo200902012, doi101016s0012825297818582, doi101016s0264817299000112, doi10102900eo00168, doi10102997rg00426, doi101046j13653091200100360x, doi101086625710, doi101086629606, doi101098rspa19540186, doi101098rsta20061810, doi101098rstl18830029, doi101111j136530911976tb00051x, doi101111j136530911977tb00122x, doi101111j13653091200801019x, doi101111j13653091200901073x, doi101146annurevfluid121108145618, doi1013062f9182e316ce11d78645000102c1865d, doi10130674d7262b2b2111d78648000102c1865d, doi102110sedred200434, nardin1979a, openalexw1570283708, openalexw580680426"
}

An outgrowth of the 2008 AAPG Hedberg Conference on Sediment Transfer from Shelf to Deep Water, Studies in Geology 61 was designed specifically to explore the growing interest in hyperpycnal and associated flows and hyperpycnites as significant contributors to the deep-water sedimentary record. The topic of hyperpycnal flows and their deposits, hyperpycnites, has recently emerged as the latest in a long list of hotly debated topics on deep-water sedimentary processes, environments, and deposits. This collection of chapters offers important new insights into the sediment delivery system to deep-marine waters.

@incollection{doi10130613271349st613438,
    author = "Zavala, Carlos and Arcuri, Mariano and Meglio, Mariano Di and Diaz, Helena Gamero and Contreras, Carmen",
    title = "A Genetic Facies Tract for the Analysis of Sustained Hyperpycnal Flow Deposits",
    year = "2012",
    booktitle = "American Association of Petroleum Geologists eBooks",
    abstract = "An outgrowth of the 2008 AAPG Hedberg Conference on Sediment Transfer from Shelf to Deep Water, Studies in Geology 61 was designed specifically to explore the growing interest in hyperpycnal and associated flows and hyperpycnites as significant contributors to the deep-water sedimentary record. The topic of hyperpycnal flows and their deposits, hyperpycnites, has recently emerged as the latest in a long list of hotly debated topics on deep-water sedimentary processes, environments, and deposits. This collection of chapters offers important new insights into the sediment delivery system to deep-marine waters.",
    url = "https://doi.org/10.1306/13271349st613438",
    doi = "10.1306/13271349st613438",
    openalex = "W2224832301",
    references = "doi101016jmarpetgeo200301003, doi101046j13653091200100360x, doi101086629747, doi101111j136530911995tb00395x, doi101111j13653091200801019x, doi101306212f7f312b2411d78648000102c1865d, doi1013065ceadd7616bb11d78645000102c1865d, doi102110scn7502, doi102110scn8209, doi104324978020337108412, harms1982structure, openalexw1570283708"
}

Hybrid fl ows comprising both turbidity current and submarine debris fl ow are a signifi cant departure from many previous infl uential models for submarine sediment density fl ows. Hybrid beds containing cohesive debrite and turbidite are common in distal depositional environments, as shown by detailed observations from more than 20 modern and ancient systems worldwide. Hybrid fl ows, and cohesive debris fl ows more generally, are best classifi ed in terms of a continuum of decreasing cohesive debris fl ow strength. High-strength cohesive debris fl ows tend to be clast rich and relatively thick, and their deposit extends back to near the site of original slope failure. They are typically confi ned to higher gradient continental slopes, but may occasionally form megabeds on basin plains, in both cases overlain by a thin turbidite. Intermediate-strength cohesive debris fl ows typically contain clasts, but their deposits may be <1 or 2 m thick on low-gradient fan fringes, and are encased in turbidite sand and mud. Clasts may be fartraveled, and meter-sized clasts can be rafted long distances across very low gradients if they are less dense than surrounding fl ow. Low-strength cohesive debris fl ows generally lack mud clasts, and as cohesive strength decreases further there is a transition into fl uid mud layers that do not support sand. Intermediate-and low-strength cohesive debrites are consistently absent in more proximal parts of submarine systems, where faster moving sediment-charged fl ows are more likely to be turbulent. Intermediatestrength debris fl ows can run out for long distances on low gradients without hydroplaning. Very low strength cohesive debris fl ows most likely form through late-stage transformations near the site of debrite deposition, and emplaced gently to avoid mixing with surrounding seawater. The location and geometry of cohesive debrites in hybrid beds are controlled strongly by seafl oor morphology and small changes in gradient. Debrites occur as fringes around raised channel-levee ridges, or in the central and lowest parts of basin plains lacking such ridges. Small variations in mud fraction produce profound changes in cohesive strength, fl ow viscosity, permeability, and the time taken for excess pore pressures to dissipate that span multiple orders of magnitude. Reduction in fl ow speed can also cause substantial increases in viscosity and yield strength in shear thinning muddy fl uids. Small amounts of sediment can dampen or extinguish turbulence, especially as fl ow decelerates, affecting how sediment is supported or deposited. This ensures that cohesive debris fl ows and hybrid fl ows have a rich variety of behaviors.

@article{doi101130ges007931,
    author = "Talling, Peter J.",
    title = "Hybrid submarine flows comprising turbidity current and cohesive debris flow: Deposits, theoretical and experimental analyses, and generalized models",
    year = "2013",
    journal = "Geosphere",
    abstract = "Hybrid fl ows comprising both turbidity current and submarine debris fl ow are a signifi cant departure from many previous infl uential models for submarine sediment density fl ows. Hybrid beds containing cohesive debrite and turbidite are common in distal depositional environments, as shown by detailed observations from more than 20 modern and ancient systems worldwide. Hybrid fl ows, and cohesive debris fl ows more generally, are best classifi ed in terms of a continuum of decreasing cohesive debris fl ow strength. High-strength cohesive debris fl ows tend to be clast rich and relatively thick, and their deposit extends back to near the site of original slope failure. They are typically confi ned to higher gradient continental slopes, but may occasionally form megabeds on basin plains, in both cases overlain by a thin turbidite. Intermediate-strength cohesive debris fl ows typically contain clasts, but their deposits may be <1 or 2 m thick on low-gradient fan fringes, and are encased in turbidite sand and mud. Clasts may be fartraveled, and meter-sized clasts can be rafted long distances across very low gradients if they are less dense than surrounding fl ow. Low-strength cohesive debris fl ows generally lack mud clasts, and as cohesive strength decreases further there is a transition into fl uid mud layers that do not support sand. Intermediate-and low-strength cohesive debrites are consistently absent in more proximal parts of submarine systems, where faster moving sediment-charged fl ows are more likely to be turbulent. Intermediatestrength debris fl ows can run out for long distances on low gradients without hydroplaning. Very low strength cohesive debris fl ows most likely form through late-stage transformations near the site of debrite deposition, and emplaced gently to avoid mixing with surrounding seawater. The location and geometry of cohesive debrites in hybrid beds are controlled strongly by seafl oor morphology and small changes in gradient. Debrites occur as fringes around raised channel-levee ridges, or in the central and lowest parts of basin plains lacking such ridges. Small variations in mud fraction produce profound changes in cohesive strength, fl ow viscosity, permeability, and the time taken for excess pore pressures to dissipate that span multiple orders of magnitude. Reduction in fl ow speed can also cause substantial increases in viscosity and yield strength in shear thinning muddy fl uids. Small amounts of sediment can dampen or extinguish turbulence, especially as fl ow decelerates, affecting how sediment is supported or deposited. This ensures that cohesive debris fl ows and hybrid fl ows have a rich variety of behaviors.",
    url = "https://doi.org/10.1130/ges00793.1",
    doi = "10.1130/ges00793.1",
    openalex = "W2122272026",
    references = "doi101016jmarpetgeo200902012, doi1010292009jf001514, doi101038nature06273, doi101046j13653091199900204x, doi101046j13653091200100360x, doi101111j136530911995tb00395x, doi101111j13653091201201353x, doi101306212f7f312b2411d78648000102c1865d, doi102475ajs25012849, openalexw1570283708"
}

Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than??0.6°. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (&lt;?0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces in seismic datasets. Validation of models, including against full-scale field data, requires clever experimental design of physical models and targeted field programs.

@article{doi102110jsr201503,
    author = "Talling, Peter J. and Allin, Joshua R. and Armitage, David and Arnott, R. W. C. and Cartigny, Matthieu and Clare, Michael and Felletti, F. and Covault, Jacob A. and Girardclos, Stéphanie and Hansen, Emily and Hill, Philip R. and Hiscott, Richard N. and Hogg, Andrew J. and Clarke, J. H. and Jobe, Zane and Malgesini, G. and Mozzato, Alessandro and Naruse, Hajime and Parkinson, S. and Peel, Frank and Piper, David J. W. and Pope, Ed and Postma, George and Rowley, Pete and Sguazzini, A. and Stevenson, C. J. and Sumner, E. J. and Sylvester, Zoltán and Watts, C. and Xu, Jingping",
    title = "Key Future Directions For Research On Turbidity Currents and Their Deposits",
    year = "2015",
    journal = "Journal of Sedimentary Research",
    abstract = "Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than??0.6°. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10\% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (\<?0.1\%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces in seismic datasets. Validation of models, including against full-scale field data, requires clever experimental design of physical models and targeted field programs.",
    url = "https://doi.org/10.2110/jsr.2015.03",
    doi = "10.2110/jsr.2015.03",
    openalex = "W2171856802",
    references = "doi101016jmarpetgeo200608001, doi101016jmarpetgeo200902012, doi101016jmarpetgeo201005002, doi101016jmarpetgeo201005012, doi101016jmarpetgeo201007008, doi101017s0022112086001404, doi1010292010gl044638, doi101038nature06273, doi101046j13653091199900204x, doi101086625710, doi101111j13653091200700926x, doi101111j13653091201201353x, doi101130b309961, doi101130ges007931, doi101146annurevfluid121108145618, doi101306212f7f312b2411d78648000102c1865d"
}

The purpose of this critical review is to address fundamental principles associated with contourites and other bottom-current deposits. The four basic types of deep-marine bottom currents are: (1) thermohaline-induced geostrophic contour currents, (2) wind-driven bottom currents, (3) tide-driven bottom currents, mostly in submarine canyons, and (4) internal wave/tide-driven baroclinic currents. Contourites are deposits of thermohaline-driven geostrophic contour currents. Contourites can be muddy or sandy in texture, siliciclastic or calciclastic in composition. Traction structures are common in deposits of all four types of bottom currents. However, there are no diagnostic sedimentological or seismic criteria for distinguishing ancient contourites from other three types. The Gulf of Cadiz is the type locality for the contourite facie model based on muddy lithofacies. However, this site is affected not only by contour currents associated with the Mediterranean Outflow Water (MOW) but also by other factors, such as internal waves and tides, turbidity currents, tsunamis, cyclones, mud volcanism, methane seepage, sediment supply, porewater venting, and bottom topography. IODP (Integrated Ocean Drilling Program) 339 cores from the Gulf of Cadiz do not show primary sedimentary structures, which are necessary for interpreting depositional processes. Therefore, the contourite facies model is sedimentologically obsolete. Bottom-current reworked sands of all four types have the potential for developing petroleum reservoirs. Modern sandy carbonate contourites have a measured maximum porosity of 40% and a maximum permeability of 9881 mD due to the winnowing away of muds from the intergranular primary pores by vigorous contour currents. These carbonate contourites are hemiconical-shaped bodies that are up to 600 m in thickness and nearly 60 km in length. Empirical data of modern contourites also show potential for seal and source-rock development. Therefore, future petroleum exploration and development should focus attention on these often overlooked siliciclastic and calciclastic deep-marine reservoirs.

@article{doi101016s187638041730023x,
    author = "Shanmugam, G.",
    title = "Contourites: Physical oceanography, process sedimentology, and petroleum geology",
    year = "2017",
    journal = "Petroleum Exploration and Development",
    abstract = "The purpose of this critical review is to address fundamental principles associated with contourites and other bottom-current deposits. The four basic types of deep-marine bottom currents are: (1) thermohaline-induced geostrophic contour currents, (2) wind-driven bottom currents, (3) tide-driven bottom currents, mostly in submarine canyons, and (4) internal wave/tide-driven baroclinic currents. Contourites are deposits of thermohaline-driven geostrophic contour currents. Contourites can be muddy or sandy in texture, siliciclastic or calciclastic in composition. Traction structures are common in deposits of all four types of bottom currents. However, there are no diagnostic sedimentological or seismic criteria for distinguishing ancient contourites from other three types. The Gulf of Cadiz is the type locality for the contourite facie model based on muddy lithofacies. However, this site is affected not only by contour currents associated with the Mediterranean Outflow Water (MOW) but also by other factors, such as internal waves and tides, turbidity currents, tsunamis, cyclones, mud volcanism, methane seepage, sediment supply, porewater venting, and bottom topography. IODP (Integrated Ocean Drilling Program) 339 cores from the Gulf of Cadiz do not show primary sedimentary structures, which are necessary for interpreting depositional processes. Therefore, the contourite facies model is sedimentologically obsolete. Bottom-current reworked sands of all four types have the potential for developing petroleum reservoirs. Modern sandy carbonate contourites have a measured maximum porosity of 40\% and a maximum permeability of 9881 mD due to the winnowing away of muds from the intergranular primary pores by vigorous contour currents. These carbonate contourites are hemiconical-shaped bodies that are up to 600 m in thickness and nearly 60 km in length. Empirical data of modern contourites also show potential for seal and source-rock development. Therefore, future petroleum exploration and development should focus attention on these often overlooked siliciclastic and calciclastic deep-marine reservoirs.",
    url = "https://doi.org/10.1016/s1876-3804(17)30023-x",
    doi = "10.1016/s1876-3804(17)30023-x",
    openalex = "W2606036022",
    references = "crossref1974the, doi1010160141118783900391, doi101016jjop201508011, doi101016jjop201606002, doi10102994jc00530, doi101038nature02494, doi10113000917613198614535scaia20co2, doi101306212f7f312b2411d78648000102c1865d, doi102110pec88010071, doi105670oceanog199107, doi105670oceanog201307, openalexw1570283708"
}

Abstract Hybrid event beds form when turbidity currents that transport or locally acquire significant quantities of mud decelerate. The mud dampens turbulence driving flow transformations, allowing both mud and sand to settle into dense, near‐bed fluid layers and debris flows. Quantifying details of the mud distribution vertically in what are often complex tiered deposits is critical to reconstructing flow processes and explaining the diverse bed types left by mud‐bearing gravity flows. High‐resolution X‐ray fluorescence core scanning provides continuous vertical compositional profiles that can help to constrain mud distribution at sub‐millimetre scale, offering a significant improvement over discrete sampling. The approach is applied here to cores acquired from the Pennsylvanian Ross Sandstone Formation, western Ireland, where a range of hybrid event beds have been identified. Raw X‐ray fluorescence counts are calibrated against element concentrations and mineral abundances determined on coincident core plugs, with element and element log‐ratios used as proxies to track vertical changes in abundances of quartz, illite (including mica), chlorite and calcite cement. New insights include ‘stepped’ (to higher values) as opposed to ‘saw‐tooth’ vertical changes in mud content and the presence of compositional banding that would otherwise be overlooked. Hybrid event beds in basin floor sheets that arrived ahead of the prograding fan system have significantly cleaner sandy components than those in mid‐fan lobes. The latter may imply that the heads of the currents emerging from mid‐fan channels entrained significant mud immediately before they collapsed. Many of the H3 debrites are bipartite with a sandier H3a division attributed to re‐entrainment and mixing of a trailing debris or fluid mud flow (H3b) with sand left by the forward part of the flow. Hybrid event bed structure may thus partly reflect substrate interaction and mixing during deposition, and the texture of the bed divisions may not simply mirror those in the suspensions from which they formed.

@article{doi101111sed12722,
    author = "Hussain, Arif and Haughton, Peter D. W. and Shannon, Patrick M. and Turner, Jonathan and Pierce, Colm and Obradors‐Latre, Arnau and Barker, Simon P. and Martinsen, Ole J.",
    title = "High‐resolution X‐ray fluorescence profiling of hybrid event beds: Implications for sediment gravity flow behaviour and deposit structure",
    year = "2020",
    journal = "Sedimentology",
    abstract = "Abstract Hybrid event beds form when turbidity currents that transport or locally acquire significant quantities of mud decelerate. The mud dampens turbulence driving flow transformations, allowing both mud and sand to settle into dense, near‐bed fluid layers and debris flows. Quantifying details of the mud distribution vertically in what are often complex tiered deposits is critical to reconstructing flow processes and explaining the diverse bed types left by mud‐bearing gravity flows. High‐resolution X‐ray fluorescence core scanning provides continuous vertical compositional profiles that can help to constrain mud distribution at sub‐millimetre scale, offering a significant improvement over discrete sampling. The approach is applied here to cores acquired from the Pennsylvanian Ross Sandstone Formation, western Ireland, where a range of hybrid event beds have been identified. Raw X‐ray fluorescence counts are calibrated against element concentrations and mineral abundances determined on coincident core plugs, with element and element log‐ratios used as proxies to track vertical changes in abundances of quartz, illite (including mica), chlorite and calcite cement. New insights include ‘stepped’ (to higher values) as opposed to ‘saw‐tooth’ vertical changes in mud content and the presence of compositional banding that would otherwise be overlooked. Hybrid event beds in basin floor sheets that arrived ahead of the prograding fan system have significantly cleaner sandy components than those in mid‐fan lobes. The latter may imply that the heads of the currents emerging from mid‐fan channels entrained significant mud immediately before they collapsed. Many of the H3 debrites are bipartite with a sandier H3a division attributed to re‐entrainment and mixing of a trailing debris or fluid mud flow (H3b) with sand left by the forward part of the flow. Hybrid event bed structure may thus partly reflect substrate interaction and mixing during deposition, and the texture of the bed divisions may not simply mirror those in the suspensions from which they formed.",
    url = "https://doi.org/10.1111/sed.12722",
    doi = "10.1111/sed.12722",
    openalex = "W3008935814",
    references = "doi101111sed12376"
}

Abstract A hyperpycnal flow forms when a relatively dense land-derived gravity flow enters into a marine or lacustrine water reservoir. As a consequence of its excess of density, the incoming flow plunges in coastal areas, generating a highly dynamic and often long-lived dense underflow. Depending on the characteristics of the parent flow (flow duration and flow rheology) and basin salinity, the resulting deposits (hyperpycnites) can be very variable. According to flow duration, land-derived gravity flows can be classified into short-lived or long-lived flows. Short-lived gravity flows last for minutes or hours, and are mostly related to small mountainous river discharges, alluvial fans, collapse of natural dams, landslides, volcanic eruptions, jökulhlaups, etc. Long-lived gravity flows last for days, weeks or even months, and are mostly associated with medium- to large-size river discharges. Concerning the rheology of the incoming flow, hyperpycnal flows can be initiated by non-Newtonian (cohesive debris flows), Newtonian supercritical (lahars, hyperconcentrated flows, and concentrated flows) or Newtonian subcritical flows (pebbly, sandy or muddy sediment-laden turbulent flows). Once plunged, non-Newtonian and Newtonian supercritical flows require steep slopes to accelerate, allow the incorporation of ambient water and develop flow transformations in order to evolve into a turbidity current and travel further basinward. Their resulting deposits are difficult to differentiate from those related to intrabasinal turbidites. On the contrary, long-lived Newtonian subcritical flows are capable of transferring huge volumes of sediment, freshwater and organic matter far from the coast even along gentle or flat slopes. In marine settings, the buoyant effect of interstitial freshwater in pebbly and sandy hyperpycnal flows can result in lofting due to flow density reversal. Since the excess of density in muddy hyperpycnal flows is provided by silt-clay sediments in turbulent suspension, lofting is not possible even in marine/saline basins. Muddy hyperpycnal flows can also erode the basin bottom during their travel basinward, allowing the incorporation and transfer of intrabasinal sediments and organic matter. Long-lived hyperpycnal flow deposits exhibit typical characteristics that allow a clear differentiation respect to those related to intrabasinal turbidites. Main features include (1) composite beds with gradual and recurrent changes in sediment grain-size and sedimentary structures, (2) mixture of extrabasinal and intrabasinal components, (3) internal and discontinuous erosional surfaces, and (4) lofting rhythmites in marine/saline basins.

@article{doi101186s4250102000065x,
    author = "Zavala, Carlos",
    title = "Hyperpycnal (over density) flows and deposits",
    year = "2020",
    journal = "Journal of Palaeogeography",
    abstract = "Abstract A hyperpycnal flow forms when a relatively dense land-derived gravity flow enters into a marine or lacustrine water reservoir. As a consequence of its excess of density, the incoming flow plunges in coastal areas, generating a highly dynamic and often long-lived dense underflow. Depending on the characteristics of the parent flow (flow duration and flow rheology) and basin salinity, the resulting deposits (hyperpycnites) can be very variable. According to flow duration, land-derived gravity flows can be classified into short-lived or long-lived flows. Short-lived gravity flows last for minutes or hours, and are mostly related to small mountainous river discharges, alluvial fans, collapse of natural dams, landslides, volcanic eruptions, jökulhlaups, etc. Long-lived gravity flows last for days, weeks or even months, and are mostly associated with medium- to large-size river discharges. Concerning the rheology of the incoming flow, hyperpycnal flows can be initiated by non-Newtonian (cohesive debris flows), Newtonian supercritical (lahars, hyperconcentrated flows, and concentrated flows) or Newtonian subcritical flows (pebbly, sandy or muddy sediment-laden turbulent flows). Once plunged, non-Newtonian and Newtonian supercritical flows require steep slopes to accelerate, allow the incorporation of ambient water and develop flow transformations in order to evolve into a turbidity current and travel further basinward. Their resulting deposits are difficult to differentiate from those related to intrabasinal turbidites. On the contrary, long-lived Newtonian subcritical flows are capable of transferring huge volumes of sediment, freshwater and organic matter far from the coast even along gentle or flat slopes. In marine settings, the buoyant effect of interstitial freshwater in pebbly and sandy hyperpycnal flows can result in lofting due to flow density reversal. Since the excess of density in muddy hyperpycnal flows is provided by silt-clay sediments in turbulent suspension, lofting is not possible even in marine/saline basins. Muddy hyperpycnal flows can also erode the basin bottom during their travel basinward, allowing the incorporation and transfer of intrabasinal sediments and organic matter. Long-lived hyperpycnal flow deposits exhibit typical characteristics that allow a clear differentiation respect to those related to intrabasinal turbidites. Main features include (1) composite beds with gradual and recurrent changes in sediment grain-size and sedimentary structures, (2) mixture of extrabasinal and intrabasinal components, (3) internal and discontinuous erosional surfaces, and (4) lofting rhythmites in marine/saline basins.",
    url = "https://doi.org/10.1186/s42501-020-00065-x",
    doi = "10.1186/s42501-020-00065-x",
    openalex = "W3036662502",
    references = "doi101016jsedgeo201603008, doi10130613271349st613438, doi102478s135330110037z"
}

Sedimentary deposits of coastal flooding by tsunamis and storms extend archives of these events across millennia. However, the utility of these records remains clouded by an inability to unequivocally differentiate between a deposit of storm or tsunami origin. This review takes a novel approach by compiling a large integrated dataset of modern and palaeo tsunami and storm deposits in coastal lakes and lagoons to infer the processes that occur during these events. We find that storm and tsunami deposits each comprise three differing groups. Using these groups, we infer the processes involved in tsunamis, including the formation of a sediment gravity flow as the tsunami flows into the lake; the progression of a dense, cohesionless flow head, or the displacement of the shallow lake water by the tsunami wave. In contrast, storm deposits are inferred to be formed by bedload under an overwash regime or in a dilute flow under full inundation of the coastal lake or lagoon. From these processes, we show that the composition of tsunami deposits is dependent on the environmental setting of the lake or lagoon whereas, for storms, the event size is a greater factor. Our findings show that in most cases, storm events are inherently unable to generate the tsunami deposits found in coastal lakes and lagoons. This insight enables the establishment of recognition criteria and a framework that can be applied to candidate deposits to differentiate unequivocally between the two event types. Nonetheless, for some deposits, a differentiation on sedimentology alone is impossible.

@article{doi101016jearscirev2025105277,
    author = "Sharrocks, Patrick D. and Peakall, Jeff and Hodgson, David M. and Barlow, Natasha",
    title = "Tsunami versus storms: Diagnostic sedimentary criteria in coastal lakes, lagoons and sinkhole deposits",
    year = "2025",
    journal = "Earth-Science Reviews",
    abstract = "Sedimentary deposits of coastal flooding by tsunamis and storms extend archives of these events across millennia. However, the utility of these records remains clouded by an inability to unequivocally differentiate between a deposit of storm or tsunami origin. This review takes a novel approach by compiling a large integrated dataset of modern and palaeo tsunami and storm deposits in coastal lakes and lagoons to infer the processes that occur during these events. We find that storm and tsunami deposits each comprise three differing groups. Using these groups, we infer the processes involved in tsunamis, including the formation of a sediment gravity flow as the tsunami flows into the lake; the progression of a dense, cohesionless flow head, or the displacement of the shallow lake water by the tsunami wave. In contrast, storm deposits are inferred to be formed by bedload under an overwash regime or in a dilute flow under full inundation of the coastal lake or lagoon. From these processes, we show that the composition of tsunami deposits is dependent on the environmental setting of the lake or lagoon whereas, for storms, the event size is a greater factor. Our findings show that in most cases, storm events are inherently unable to generate the tsunami deposits found in coastal lakes and lagoons. This insight enables the establishment of recognition criteria and a framework that can be applied to candidate deposits to differentiate unequivocally between the two event types. Nonetheless, for some deposits, a differentiation on sedimentology alone is impossible.",
    url = "https://doi.org/10.1016/j.earscirev.2025.105277",
    doi = "10.1016/j.earscirev.2025.105277",
    openalex = "W4414256133",
    references = "doi101111sed12376"
}

@incollection{bryant2026sedimentology,
    author = "Bryant, Ian D.",
    title = "Sedimentology of glaciofluvial deposits",
    year = "2026",
    booktitle = "Glacial Deposits in Great Britain and Ireland",
    url = "https://doi.org/10.1201/9781003763413-43",
    doi = "10.1201/9781003763413-43",
    openalex = "W7125960282",
    pages = "437-442"
}

@misc{crossrefNonesedimentology,
    title = "Sedimentology of tsunami deposits",
    year = "None",
    booktitle = "AccessScience",
    url = "https://doi.org/10.1036/1097-8542.yb070240",
    doi = "10.1036/1097-8542.yb070240",
    openalex = "W2561512354"
}