North america

@article{s27079f584e9eae7555a172cc2bd14f932d125fe2e,
    author = "Walcott, C.",
    title = "Abrupt appearance of the Cambrian fauna on the North American continent",
    url = "https://www.semanticscholar.org/paper/7079f584e9eae7555a172cc2bd14f932d125fe2e",
    is_oa = "true",
    semanticscholar_citation_count = "17",
    semanticscholar_id = "7079f584e9eae7555a172cc2bd14f932d125fe2e"
}

@article{cope1870synopsis2,
    author = "Cope, E. D",
    title = "Synopsis of the extinct Batrachia, Reptilia, and Aves of North America",
    year = "1870",
    journal = "American Philosophical Society Transactions, n.s., v. 14, p. 1-252",
    note = "talkorigins\_source = {true}; raw\_reference = {Cope, E. D., 1870, Synopsis of the extinct Batrachia, Reptilia, and Aves of North America: American Philosophical Society Transactions, n.s., v. 14, p. 1-252.}"
}

@inproceedings{cope1887a3,
    author = "Cope, E. D",
    title = "A contribution to the history of the vertebrata of the Trias of North America",
    year = "1887",
    booktitle = "Proceedings of the American Philosophical Society, v. XXIV, p. 209-228",
    note = "talkorigins\_source = {true}; raw\_reference = {Cope, E. D., 1887, A contribution to the history of the vertebrata of the Trias of North America: Proceedings of the American Philosophical Society, v. XXIV, p. 209-228.}"
}

Considerable attention has been given of late years to the faunas of the rocks in North America considered to be the equivalents of the rocks usually classed as Cambrian in this country, and the facts which have been obtained are particularly interesting to British geologists. Two recent communications by Mr. C. D. Walcott, Palaeontologist to the U. S. Geological Survey, are especially deserving of study in reference to the classification of these rocks, and many facts of importance bearing on the same question are also given in papers by Mr. G. F. Matthew, of St. John's, N.B.

@article{hicks1887ivthe,
    author = "Hicks, Henry",
    title = "IV.—The Cambrian Books of North America",
    year = "1887",
    journal = "Geological Magazine",
    abstract = "Considerable attention has been given of late years to the faunas of the rocks in North America considered to be the equivalents of the rocks usually classed as Cambrian in this country, and the facts which have been obtained are particularly interesting to British geologists. Two recent communications by Mr. C. D. Walcott, Palaeontologist to the U. S. Geological Survey, are especially deserving of study in reference to the classification of these rocks, and many facts of importance bearing on the same question are also given in papers by Mr. G. F. Matthew, of St. John's, N.B.",
    url = "https://doi.org/10.1017/s0016756800196402",
    doi = "10.1017/s0016756800196402",
    number = "4",
    pages = "155-158",
    volume = "4"
}

@misc{walcott1891the8,
    author = "Walcott, C. D",
    title = "The North American Continent During Cambrian Time, in Twelfth Annual Report, United States Geological Survey",
    year = "1891",
    howpublished = "Washington, D.C., United States Geological Survey, p. 523-568",
    note = "talkorigins\_source = {true}; raw\_reference = {Walcott, C. D., 1891, The North American Continent During Cambrian Time, in Twelfth Annual Report, United States Geological Survey: Washington, D.C., United States Geological Survey, p. 523-568.}"
}

@misc{crossref1909precambrian,
    title = "Pre-Cambrian geology of North America",
    year = "1909",
    url = "https://doi.org/10.3133/b360",
    doi = "10.3133/b360"
}

@misc{walcott1910abrupt9,
    author = "Walcott, C. D",
    title = "Abrupt appearance of the Cambrian fauna on the North American continent",
    year = "1910",
    howpublished = "Cambrian Geology and Paleontology, II: Smithsonian Miscellaneous Collections, v. 57, p. 1-16",
    note = "talkorigins\_source = {true}; raw\_reference = {Walcott, C. D., 1910, Abrupt appearance of the Cambrian fauna on the North American continent: Cambrian Geology and Paleontology, II: Smithsonian Miscellaneous Collections, v. 57, p. 1-16.}"
}

@article{miller1923precambrian,
    author = "MILLER, W. J.",
    title = "Pre-Cambrian Folding in North America",
    year = "1923",
    journal = "Geological Society of America Bulletin",
    url = "https://doi.org/10.1130/gsab-34-679",
    doi = "10.1130/gsab-34-679",
    number = "4",
    pages = "679-702",
    volume = "34"
}

@incollection{thistlethwaite1957the,
    author = "Thistlethwaite, Frank",
    title = "The North American continent",
    year = "1957",
    booktitle = "The New Cambridge Modern History",
    url = "https://doi.org/10.1017/chol9780521045452.026",
    doi = "10.1017/chol9780521045452.026",
    pages = "528-540"
}

@article{cloud1973possible1,
    author = "Cloud, P. E",
    title = "Possible stratotype sequences for the basal Paleozoic in North America",
    year = "1973",
    journal = "American Journal of Science, v. 273, p. 193-206",
    note = "talkorigins\_source = {true}; raw\_reference = {Cloud, P. E., 1973, Possible stratotype sequences for the basal Paleozoic in North America: American Journal of Science, v. 273, p. 193-206.}"
}

@misc{hallam1977secular5,
    author = "Hallam, A",
    title = "Secular changes in marine inundation of USSR and North America during the Phanerozoic",
    year = "1977",
    howpublished = "Nature, v. 269, p. 769-772",
    note = "talkorigins\_source = {true}; raw\_reference = {Hallam, A., 1977, Secular changes in marine inundation of USSR and North America during the Phanerozoic: Nature, v. 269, p. 769-772.}"
}

@article{rowell1979margin,
    author = "Rowell, A. J. and Rees, M. N. and Suczek, C. A.",
    title = "Margin of the North American continent in Nevada during Late Cambrian time",
    year = "1979",
    journal = "American Journal of Science",
    url = "https://doi.org/10.2475/ajs.279.1.1",
    doi = "10.2475/ajs.279.1.1",
    number = "1",
    pages = "1-18",
    volume = "279"
}

@misc{galton1982elaphrosaurus4,
    author = "Galton, P. M",
    title = "Elaphrosaurus, an ornithomimid dinosaur from the Upper Jurassic of North America and Africa",
    year = "1982",
    howpublished = "Palontologische Zeitschrift, v. 56, p. 265-275",
    note = "talkorigins\_source = {true}; raw\_reference = {Galton, P. M., 1982, Elaphrosaurus, an ornithomimid dinosaur from the Upper Jurassic of North America and Africa: Palontologische Zeitschrift, v. 56, p. 265-275.}"
}

@misc{lehman1987late6,
    author = "Lehman, T. M",
    title = "Late Maastrichtian paleoenvironments and dinosaur biogeography in the western interior of North America",
    year = "1987",
    howpublished = "Palaeogeography, Palaeoclimatology, Palaeoecology, v. 60, p. 189-217",
    note = "talkorigins\_source = {true}; raw\_reference = {Lehman, T. M., 1987, Late Maastrichtian paleoenvironments and dinosaur biogeography in the western interior of North America: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 60, p. 189-217.}"
}

@misc{rigby1987the7,
    author = "Rigby, J. K",
    title = "The Last of the North American Dinosaurs, in Czerkas, S. J., and Olson, E. C., eds., Dinosaurs Past and Present, II",
    year = "1987",
    howpublished = "Los Angeles, Natural History Museum of Los Angeles County, p. 119-135",
    note = "talkorigins\_source = {true}; raw\_reference = {Rigby, J. K., 1987, The Last of the North American Dinosaurs, in Czerkas, S. J., and Olson, E. C., eds., Dinosaurs Past and Present, II: Los Angeles, Natural History Museum of Los Angeles County, p. 119-135.}"
}

@misc{crossref1989north,
    title = "North American Continent-Ocean Transects Program",
    year = "1989",
    url = "https://doi.org/10.17226/1521",
    doi = "10.17226/1521"
}

@article{ghosh2013dynamics,
    author = "Ghosh, A. and Becker, T. W. and Humphreys, E. D.",
    title = "Dynamics of the North American continent",
    year = "2013",
    journal = "Geophysical Journal International",
    url = "https://doi.org/10.1093/gji/ggt151",
    doi = "10.1093/gji/ggt151",
    number = "2",
    pages = "651-669",
    volume = "194"
}

S of sedimentary pyrite. Further local redox conditions, tracked using iron speciation analysis, indicate anoxic conditions developed at the two proximal locations after the start of the paired isotopic excursions. However, the location near the basin center shows no indication for anoxia before or during the onset of the SPICE. While this signal may reflect the structure of local redox conditions within the basin, with the development of anoxia limited to the basin margins, we argue that authigenic iron enrichments were muted by sedimentary dilution and/or the enhanced authigenesis of iron-bearing sheet silicates near the basin center, masking the signal for anoxia there. Regardless of the areal extent of anoxia within the basin, in either scenario the timing of the development of anoxic bottom waters was concurrent with local faunal turnover, features broadly consistent with a global expansion of anoxia playing a role in driving the isotopic trends and extinctions observed during the event.

@article{doi101111gbi12334,
    author = "LeRoy, Matthew A. and Gill, Benjamin C.",
    title = "Evidence for the development of local anoxia during the Cambrian SPICE event in eastern North America",
    year = "2019",
    journal = "Geobiology",
    abstract = "S of sedimentary pyrite. Further local redox conditions, tracked using iron speciation analysis, indicate anoxic conditions developed at the two proximal locations after the start of the paired isotopic excursions. However, the location near the basin center shows no indication for anoxia before or during the onset of the SPICE. While this signal may reflect the structure of local redox conditions within the basin, with the development of anoxia limited to the basin margins, we argue that authigenic iron enrichments were muted by sedimentary dilution and/or the enhanced authigenesis of iron-bearing sheet silicates near the basin center, masking the signal for anoxia there. Regardless of the areal extent of anoxia within the basin, in either scenario the timing of the development of anoxic bottom waters was concurrent with local faunal turnover, features broadly consistent with a global expansion of anoxia playing a role in driving the isotopic trends and extinctions observed during the event.",
    url = "https://doi.org/10.1111/gbi.12334",
    doi = "10.1111/gbi.12334",
    openalex = "W2912082921",
    references = "doi101016jgsf201602004"
}

Uranium-lead (U-Pb) zircon dating establishes a late Cambrian (Drumian) protolith age of 503 ± 2 Ma for a trondhjemitic gneiss of the calc-alkaline Strathy Complex, northern Scottish Caledonides. Positive εHf and εNd values from trondhjemitic gneisses and co-magmatic amphibolites, respectively, and an absence of any inheritance in zircon populations support published geochemistry that indicates a juvenile origin distal from Laurentia. In order to account for its present location within a stack of Laurentia-derived thrust sheets, we interpret the complex as allochthonous and located along a buried suture. We propose that a microcontinental ribbon was detached from Laurentia during late Neoproterozoic to Cambrian rifting; the intervening oceanic tract closed by subduction during the late Cambrian and formed a juvenile arc, the protolith of the Strathy Complex. The microcontinental ribbon was reattached to Laurentia during the Grampian orogeny, which transported the Strathy Complex as a tectonic slice within a nappe stack. Peak metamorphic conditions for the Strathy Complex arc (650–700 °C, 0.6–0.75 GPa) are intermediate in pressure between those published previously for Grampian mineral assemblages in structurally overlying low-pressure migmatites (670–750 °C, <0.4 GPa) that we deduce to have been derived from an adjacent backarc basin, and structurally underlying upper amphibolite rocks (650–700 °C, 1.1–1.2 GPa) that we interpret to represent the partially subducted Laurentian margin. This scenario compares with that of the northern Appalachian Mountains and Norway where microcontinental blocks are interpreted to have their origins in detachment from passive margins of the Iapetus Ocean during Cambrian rifting and to have been re-amalgamated during Caledonian orogenesis.

@article{doi101130g461801,
    author = "Dunk, M. and Strachan, R. and Cutts, K. and Lasalle, Stéphanie and Storey, C. and Burns, I. M. and Whitehouse, M. and Fowler, M. and Moreira, H. and Dunlop, J. and Pereira, I.",
    title = "Evidence for a late Cambrian juvenile arc and a buried suture within the Laurentian Caledonides of Scotland: Comparisons with hyperextended Iapetan margins in the Appalachian Mountains (North America) and Norway",
    year = "2019",
    journal = "Geology",
    abstract = "Uranium-lead (U-Pb) zircon dating establishes a late Cambrian (Drumian) protolith age of 503 ± 2 Ma for a trondhjemitic gneiss of the calc-alkaline Strathy Complex, northern Scottish Caledonides. Positive εHf and εNd values from trondhjemitic gneisses and co-magmatic amphibolites, respectively, and an absence of any inheritance in zircon populations support published geochemistry that indicates a juvenile origin distal from Laurentia. In order to account for its present location within a stack of Laurentia-derived thrust sheets, we interpret the complex as allochthonous and located along a buried suture. We propose that a microcontinental ribbon was detached from Laurentia during late Neoproterozoic to Cambrian rifting; the intervening oceanic tract closed by subduction during the late Cambrian and formed a juvenile arc, the protolith of the Strathy Complex. The microcontinental ribbon was reattached to Laurentia during the Grampian orogeny, which transported the Strathy Complex as a tectonic slice within a nappe stack. Peak metamorphic conditions for the Strathy Complex arc (650–700 °C, 0.6–0.75 GPa) are intermediate in pressure between those published previously for Grampian mineral assemblages in structurally overlying low-pressure migmatites (670–750 °C, <0.4 GPa) that we deduce to have been derived from an adjacent backarc basin, and structurally underlying upper amphibolite rocks (650–700 °C, 1.1–1.2 GPa) that we interpret to represent the partially subducted Laurentian margin. This scenario compares with that of the northern Appalachian Mountains and Norway where microcontinental blocks are interpreted to have their origins in detachment from passive margins of the Iapetus Ocean during Cambrian rifting and to have been re-amalgamated during Caledonian orogenesis.",
    url = "https://researchportal.port.ac.uk/files/14336524/Evidence\_for\_a\_late\_Cambrian\_juvenile\_arc.pdf",
    doi = "10.1130/G46180.1",
    is_oa = "true",
    number = "8",
    pages = "734-738",
    semanticscholar_citation_count = "18",
    semanticscholar_id = "13aac4a03c35a7661ae3cd50f85d2ec4645825a2",
    volume = "47"
}

@inproceedings{andlanding2021cambrian,
    author = "Landing, Ed",
    title = "CAMBRIAN CHRONOSTRATIGAPHIC UNITS IN NORTH AMERICA",
    year = "2021",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://doi.org/10.1130/abs/2021am-367250",
    doi = "10.1130/abs/2021am-367250"
}

Documenting the patterns and potential associated processes of ancient biotas has always been a central challenge in palaeontology. Over recent decades, intense debate has focused on the organization of dinosaur‐dominated communities, yet no general consensus has been reached on how these communities were organized in a spatial context. Here, we used analytical routines typically applied in metacommunity ecology to provide novel insights into dinosaurian distributions across the latest Cretaceous of North America. To do this, we combined fossil occurrences with functional, phylogenetic and palaeoenvironmental modelling, and adopted the perspective that more reasonable conclusions on palaeoecological reconstructions can be gained from studies that consider the organization of biotas along ecological gradients at multiple spatial scales. Our results showed that dinosaurs were restricted in range to different parts of the Hell Creek Formation, prompting the recognition of discrete and compartmentalized faunal areas during the Maastrichtian at fine‐grained scales, whereas taxa with the broadest ranges included those with narrower distributions when combining data from various geological formations across the Western Interior of North America. Although groups of dinosaurs had coincident range boundaries, their communities responded to multiple ecologically‐important gradients when compensating for differences in sampling effort. Metacommunity structures of both ornithischians and theropods were correlated with climatic barriers and potential trophic relationships between herbivores and carnivores, thereby suggesting that dinosaurian faunas were shaped by physiological constraints, limited food resources abundance, and a combination of bottom‐up and top‐down forces across multiple spatial grains and extents.

@article{doi101111pala12526,
    author = "García–Girón, Jorge and Heino, J. and Alahuhta, J. and Chiarenza, Alfio Alessandro and Brusatte, S.",
    title = "Palaeontology meets metacommunity ecology: the Maastrichtian dinosaur fossil record of North America as a case study",
    year = "2021",
    journal = "Palaeontology",
    abstract = "Documenting the patterns and potential associated processes of ancient biotas has always been a central challenge in palaeontology. Over recent decades, intense debate has focused on the organization of dinosaur‐dominated communities, yet no general consensus has been reached on how these communities were organized in a spatial context. Here, we used analytical routines typically applied in metacommunity ecology to provide novel insights into dinosaurian distributions across the latest Cretaceous of North America. To do this, we combined fossil occurrences with functional, phylogenetic and palaeoenvironmental modelling, and adopted the perspective that more reasonable conclusions on palaeoecological reconstructions can be gained from studies that consider the organization of biotas along ecological gradients at multiple spatial scales. Our results showed that dinosaurs were restricted in range to different parts of the Hell Creek Formation, prompting the recognition of discrete and compartmentalized faunal areas during the Maastrichtian at fine‐grained scales, whereas taxa with the broadest ranges included those with narrower distributions when combining data from various geological formations across the Western Interior of North America. Although groups of dinosaurs had coincident range boundaries, their communities responded to multiple ecologically‐important gradients when compensating for differences in sampling effort. Metacommunity structures of both ornithischians and theropods were correlated with climatic barriers and potential trophic relationships between herbivores and carnivores, thereby suggesting that dinosaurian faunas were shaped by physiological constraints, limited food resources abundance, and a combination of bottom‐up and top‐down forces across multiple spatial grains and extents.",
    url = "https://www.pure.ed.ac.uk/ws/files/186137834/606.\_Brusatte.pdf",
    doi = "10.1111/pala.12526",
    is_oa = "true",
    number = "3",
    pages = "335-357",
    semanticscholar_citation_count = "17",
    semanticscholar_id = "f05981153383be1561200847d669495dab40fe4c",
    volume = "64"
}

Abstract Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages requires spatiotemporally contiguous data; however, there remains a spatial and temporal disparity in dinosaur data on the continent. The rarity of vertebrate-bearing sedimentary deposits representing Turonian–Santonian ecosystems, and the relatively sparse record of dinosaurs from the eastern portion of the continent, present persistent challenges for studies of North American dinosaur evolution. Here we describe an assemblage of ornithomimosaurian materials from the Santonian Eutaw Formation of Mississippi. Morphological data coupled with osteohistological growth markers suggest the presence of two taxa of different body sizes, including one of the largest ornithomimosaurians known worldwide. The regression predicts a femoral circumference and a body mass of the Eutaw individuals similar to or greater than that of large-bodied ornithomimosaurs, Beishanlong grandis and Gallimimus bullatus. The paleohistology of MMNS VP-6332 demonstrates that the individual was at least 11 years of age (similar to B. grandis [∼375 kg, 13–14 years old at death]). Additional pedal elements share some intriguing features with ornithomimosaurs yet suggest a larger-body size closer to Deinocheirus mirificus. The presence of a large-bodied ornithomimosaur in this region during this time is consistent with the relatively recent discoveries of early-diverging, large-bodied ornithomimosaurs from mid-Cretaceous strata of Laurasia (Arkansaurus fridayi and B. grandis). The smaller Eutaw taxon is represented by a tibia preserving seven growth cycles, with osteohistological indicators of decreasing growth, yet belongs to an individual with near reaching somatic maturity of the larger taxon, suggesting the co-existence of medium- and large-bodied ornithomimosaur taxa during the Late Cretaceous Santonian of North America. The Eutaw ornithomimosaur materials provide key information on the diversity and distribution of North American ornithomimosaurs and Appalachian dinosaurs and fit with broader evidence of multiple cohabiting species of ornithomimosaurian dinosaurs in Late Cretaceous ecosystems of Laurasia.

@misc{doi10110120220325485782,
    author = "Chinzorig, Tsogtbaatar and Cullen, Thomas M. and Phillips, George E. and Rolke, Richard and Zanno, Lindsay E.",
    title = "Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America",
    year = "2022",
    booktitle = "bioRxiv (Cold Spring Harbor Laboratory)",
    abstract = "Abstract Reconstructing the evolution, diversity, and paleobiogeography of North America’s Late Cretaceous dinosaur assemblages requires spatiotemporally contiguous data; however, there remains a spatial and temporal disparity in dinosaur data on the continent. The rarity of vertebrate-bearing sedimentary deposits representing Turonian–Santonian ecosystems, and the relatively sparse record of dinosaurs from the eastern portion of the continent, present persistent challenges for studies of North American dinosaur evolution. Here we describe an assemblage of ornithomimosaurian materials from the Santonian Eutaw Formation of Mississippi. Morphological data coupled with osteohistological growth markers suggest the presence of two taxa of different body sizes, including one of the largest ornithomimosaurians known worldwide. The regression predicts a femoral circumference and a body mass of the Eutaw individuals similar to or greater than that of large-bodied ornithomimosaurs, Beishanlong grandis and Gallimimus bullatus. The paleohistology of MMNS VP-6332 demonstrates that the individual was at least 11 years of age (similar to B. grandis [∼375 kg, 13–14 years old at death]). Additional pedal elements share some intriguing features with ornithomimosaurs yet suggest a larger-body size closer to Deinocheirus mirificus. The presence of a large-bodied ornithomimosaur in this region during this time is consistent with the relatively recent discoveries of early-diverging, large-bodied ornithomimosaurs from mid-Cretaceous strata of Laurasia (Arkansaurus fridayi and B. grandis). The smaller Eutaw taxon is represented by a tibia preserving seven growth cycles, with osteohistological indicators of decreasing growth, yet belongs to an individual with near reaching somatic maturity of the larger taxon, suggesting the co-existence of medium- and large-bodied ornithomimosaur taxa during the Late Cretaceous Santonian of North America. The Eutaw ornithomimosaur materials provide key information on the diversity and distribution of North American ornithomimosaurs and Appalachian dinosaurs and fit with broader evidence of multiple cohabiting species of ornithomimosaurian dinosaurs in Late Cretaceous ecosystems of Laurasia.",
    url = "https://doi.org/10.1101/2022.03.25.485782",
    doi = "10.1101/2022.03.25.485782",
    openalex = "W4221005639",
    references = "doi101098rsos210127"
}

At perhaps the coarsest scale of consideration, the rock cycle operates through fluxes associated with tectonic uplift and erosion, which are generally balanced by subsidence/subduction and the burial of mineral materials that leads to volumetric balance among the principal rock reservoirs. At Earth’s surface, net rates of transfer are manifest as the reduction of areas of older rocks during erosional destruction as well as during burial by younger units. Because exposure of continental crust comprises some finite space, decrease of older rock area by erosion and/or burial must be largely balanced by an increase in area of new sedimentary and volcanic successions. Here, we examine relations between the lateral extents of rock units exposed across North America—their lithology, elevation, and the age of formation—to determine rates of geologic “repaving” that are recorded in the age and area of rocks making up the surface of the continent. Moreover, because deposition occurs at lower elevations, one might expect that subsequent episodes of uplift and/or burial would serve to increase the average elevation of currently exposed sedimentary lithosomes. Because plutonic and metamorphic rocks form at depth and are only exposed along orogenic belts and across shields after extended intervals of uplift and/or erosion, one might expect basement rocks to be initially exposed at higher elevations, and that subsequent erosion would decrease elevation with increasing age. Therefore, processes giving rise to associations between outcrop lithology, extent, and elevation may serve as measures of continent-scale rates of rock cycling. We combine data from the 1 arc-minute global relief model with data from the Geological Society of America’s 2005 Geologic Map of North America to assess the actuality and significance of first-order relations among the lithologies, areas, ages, and elevations of rock bodies now exposed across the North American continent and how these may shed light on deep-time rates of rock cycling. Areas of the 23,642 mapped North American lithosomes make up a lognormal frequency distribution (mode = 121 km2). This distribution reflects both natural (lateral extents of individual map units must be limited in space) and anthropogenic (cartographers must render map units within limited range of sizes) causes. Contiguous, lateral associations of the major rock types suggest that the spatial occurrence of volcanic and sedimentary rock bodies is largely independent of the proximity of other rock types, but exposures of plutonic and metamorphic lithosomes are intimately associated in space and thus comprise the “crystalline basement” exposed in cores of younger orogens and across the Canadian Shield. Unlike sedimentary and volcanic rocks that “attain their age” when formed at Earth’s surface, plutonic and metamorphic units are “born” at depth and therefore must have reached some antiquity prior to first exposure. As a result, the ages of volcanic and sedimentary exposures span the full range of ages represented by all lithologies, while those of plutonic and metamorphic suites are more abbreviated and older. Median ages of North American volcanic, sedimentary, plutonic, and metamorphic exposures are 482 Ma, 306 Ma, 1695 Ma, and 2467 Ma, respectively. Although the areal extent of sedimentary rock decreases with increasing age, elevation increases. This change is interpreted as reflecting progressive tectonic uplift from initial accumulation at lower elevations. In contrast, the surfaces of exposed volcanic, plutonic, and metamorphic lithosomes become lower in elevation with increasing age. This change reflects both the erosional lowering of lithosome surfaces as well as the progressive exhumation of larger areas of crystalline basement. Exposed rock area exhibits a power law decrease with increasing age. This change reflects the progressive destruction of older units and their burial by younger units. A simple “repaving” model in which 0.8% area is uplifted and eroded per million years is in good agreement with observed relations of map age versus area, the rate of which is equivalent to the resurfacing of the North American continent every 63 m.y. or ∼56 times over the past 3.5 Ga. The rate of decrease in map area of exposed rocks with increasing age evident in both geologic map data and repaving models is about three times the rate of decrease in total sediment volume as determined from stratigraphic data and repaving models. The decrease in the areas of exposed rock units is primarily the result of burial by younger units rather than erosive destruction.

@article{doi101130b370611,
    author = "Wilkinson, Bruce and Consuegra, Nicolas Perez",
    title = "On the crumpling and repaving of the North American continent",
    year = "2023",
    journal = "Geological Society of America Bulletin",
    abstract = "At perhaps the coarsest scale of consideration, the rock cycle operates through fluxes associated with tectonic uplift and erosion, which are generally balanced by subsidence/subduction and the burial of mineral materials that leads to volumetric balance among the principal rock reservoirs. At Earth’s surface, net rates of transfer are manifest as the reduction of areas of older rocks during erosional destruction as well as during burial by younger units. Because exposure of continental crust comprises some finite space, decrease of older rock area by erosion and/or burial must be largely balanced by an increase in area of new sedimentary and volcanic successions. Here, we examine relations between the lateral extents of rock units exposed across North America—their lithology, elevation, and the age of formation—to determine rates of geologic “repaving” that are recorded in the age and area of rocks making up the surface of the continent. Moreover, because deposition occurs at lower elevations, one might expect that subsequent episodes of uplift and/or burial would serve to increase the average elevation of currently exposed sedimentary lithosomes. Because plutonic and metamorphic rocks form at depth and are only exposed along orogenic belts and across shields after extended intervals of uplift and/or erosion, one might expect basement rocks to be initially exposed at higher elevations, and that subsequent erosion would decrease elevation with increasing age. Therefore, processes giving rise to associations between outcrop lithology, extent, and elevation may serve as measures of continent-scale rates of rock cycling. We combine data from the 1 arc-minute global relief model with data from the Geological Society of America’s 2005 Geologic Map of North America to assess the actuality and significance of first-order relations among the lithologies, areas, ages, and elevations of rock bodies now exposed across the North American continent and how these may shed light on deep-time rates of rock cycling. Areas of the 23,642 mapped North American lithosomes make up a lognormal frequency distribution (mode = 121 km2). This distribution reflects both natural (lateral extents of individual map units must be limited in space) and anthropogenic (cartographers must render map units within limited range of sizes) causes. Contiguous, lateral associations of the major rock types suggest that the spatial occurrence of volcanic and sedimentary rock bodies is largely independent of the proximity of other rock types, but exposures of plutonic and metamorphic lithosomes are intimately associated in space and thus comprise the “crystalline basement” exposed in cores of younger orogens and across the Canadian Shield. Unlike sedimentary and volcanic rocks that “attain their age” when formed at Earth’s surface, plutonic and metamorphic units are “born” at depth and therefore must have reached some antiquity prior to first exposure. As a result, the ages of volcanic and sedimentary exposures span the full range of ages represented by all lithologies, while those of plutonic and metamorphic suites are more abbreviated and older. Median ages of North American volcanic, sedimentary, plutonic, and metamorphic exposures are 482 Ma, 306 Ma, 1695 Ma, and 2467 Ma, respectively. Although the areal extent of sedimentary rock decreases with increasing age, elevation increases. This change is interpreted as reflecting progressive tectonic uplift from initial accumulation at lower elevations. In contrast, the surfaces of exposed volcanic, plutonic, and metamorphic lithosomes become lower in elevation with increasing age. This change reflects both the erosional lowering of lithosome surfaces as well as the progressive exhumation of larger areas of crystalline basement. Exposed rock area exhibits a power law decrease with increasing age. This change reflects the progressive destruction of older units and their burial by younger units. A simple “repaving” model in which 0.8\% area is uplifted and eroded per million years is in good agreement with observed relations of map age versus area, the rate of which is equivalent to the resurfacing of the North American continent every 63 m.y. or ∼56 times over the past 3.5 Ga. The rate of decrease in map area of exposed rocks with increasing age evident in both geologic map data and repaving models is about three times the rate of decrease in total sediment volume as determined from stratigraphic data and repaving models. The decrease in the areas of exposed rock units is primarily the result of burial by younger units rather than erosive destruction.",
    url = "https://gsapubs.figshare.com/articles/journal\_contribution/Supplemental\_Material\_On\_the\_crumpling\_and\_repaving\_of\_the\_North\_American\_continent/23800665/2/files/41864817.pdf",
    doi = "10.1130/b37061.1",
    is_oa = "true",
    semanticscholar_citation_count = "3",
    semanticscholar_id = "a0b07b2d65a23624469aaa1a8f129baed2b1ab32"
}

The Devonian strata in New York State were the standard section for North America for over 100 years, and remain a significant reference for regional to global correlation and research. Since publication of L. V. Rickard’s (1975) New York Devonian correlation chart, various higher-resolution stratigraphic analyses have been employed, sometimes at bed-by-bed scale. These include sequence-, bio-, event-, chemo-, and other -stratigraphic approaches, along with increasingly finer-resolution geochronologic dating of airfall volcanic tephras. Results have led to many new interpretations and insights of the succession. The purpose of this three-volume work is to produce a new Devonian stratigraphic synthesis for New York State, and to record, often in detail, current knowledge of the succession, and various other geologic and paleontologic aspects of it for current and future research and discussion. The purpose of this chapter is to provide overviews of the Devonian Period, the Devonian of North America (“Laurentia”), the Devonian of eastern Laurentia, and the Devonian of New York State. Furthermore, this review extends beyond the sedimentary rock and paleobiological record, and beyond the United States, Canada, and northern Mexico, to also summarize aspects of Devonian orogenesis, metasedimentary foreland basin fill, silicic igneous activity, complexities of terranes of Mexico and Central America, and Appalachian faunas that extended into South America. The Devonian Period as a whole encompasses 60 million years of time, approximately 419 to 359 million years ago. During that time, shallow seas covered large continental areas; climate was warmer globally than our current climate, during the late stage of a global greenhouse climate. By the end of the Devonian, that warm climate was descending into a time of global icehouse conditions, with widespread glaciation. The positions of modern continental masses were much different. During the Devonian Period, Life first fully colonized the land, led by primitive spore-bearing plants, small arthropods, and apparently by the Middle Devonian, the first tetrapod (“four-legged”) animals, which evolved from bony fishes. Decimeter-tall plants at the beginning of the period had evolved to tree-size forms by the Middle Devonian, approximately 30 million years later, and Earth’s first forest ecosystems arose. Devonian strata are widespread around the ancient continent “Laurentia,” which approximately corresponds to modern North America). At that time, Laurentia straddled the equator, with New York State and the Appalachian region somewhat north of 30° south latitude. Shallow epicontinental seas covered large but varying amounts of the continent over the period. Mountain belts formed on the eastern, northern, and western margins of Laurentia, due to plate tectonic collisions with smaller continental masses, exotic terranes, and volcanic island arcs. Through the Early to Middle Devonian, seas in western and eastern Laurentia were separated by a “transcontinental arch,” and generally had distinctly different marine faunas. In the latest Middle Devonian, sea level transgressed over the land barrier of the Laurentian Transcontinental Arch and the Canadian Shield, and those marine faunas mixed, leading to a more global cosmopolitan fauna in the Late Devonian. Anomalously, however, Early and Middle Devonian Laurentian shallow marine faunas are found in Devonian rocks in Central and South America, which were part of the southern Gondwana continent, generally thought to be separated from Laurentia by oceanic water depths at that time. During the Devonian, eastern Laurentia was an active tectonic margin, related to continent-continent collisions with various terranes/smaller continental masses. The Caledonian, Acadian, and Neoacadian orogenies resulted in compressional and some transpressional tectonics, and the uplift of an extensive mountain belt from east Greenland to Alabama and Georgia. Crustal loading of the orogen in eastern Laurentia led to subsidence and formation of a retroarc Acadian-Neoacadian Foreland Basin, which was initially filled with marine waters, followed by gradual overfilling to above sea level by massive volumes of synorogenic sediments from the east. The resulting lands were the site of some of the earliest forests on Earth, preserved at several sites in New York State, and forest ecosystems. Large-scale deformation, seismic activity, and metamorphism in the mountain belt were accompanied by igneous processes, including explosive eruption of felsic volcanic ash and other material, collectively termed “tephra,” also sometimes termed ash or tuff layers, or if diagenetically altered, sometimes termed bentonite, K-bentonite, metabentonite, or tonstein layers. These explosive Devonian eruptions sent volcanic tephra high into the atmosphere, and easterly winds spread airfall volcanic “tephra layers” across the eastern United States. Meanwhile, rock decay in the mountains led to the erosion, transport, and deposition of massive volumes of clays, silt, sand, and gravel into the Acadian-Neoacadian Foreland Basin, and beyond. Devonian rocks in New York are found at or just below the surface across approximately 40% of the state (~50,500 km2/19,500 mi2). The strata are generally undeformed and gently dipping, and while often covered by soil, glacial sediments, and vegetative cover, are relatively widely found in natural and man-made exposures. Three relatively thin intervals of carbonates are accompanied by eastward thickening wedges of synorogenic mudrocks, sandstones, and minor conglomerates. The history of geological and paleontological observation and study in New York began in the late 18th century. The first professional geologists appeared in the early 19th century. Since the advent of the first geological survey of New York State in 1836, the Devonian Period (nearly termed the “Erian Period” for New York’s Devonian-age rocks) has been the focus of a great volume of research which continues today. The Devonian succession in New York includes strata from all seven stages of the period, with erosional gaps of small to major significance. In addition to a range of marine facies, nearly one quarter of the entire area of Devonian bedrock in the state was deposited in terrestrial settings, with massive volumes of siliciclastic sediments shed off of Acadian-Neoacadian highlands to the east, that also feature the fossils of Earth’s oldest known forest ecosystems. The stratigraphic philosophy in New York has long evolved toward a hybrid classification, wherein groups, formations, and bed-level units are largely time-rock/allostratigraphic to occasionally chronostratigraphic, with lithostratigraphy often ascribed to member-level divisions (e.g., Pragian to Givetian strata, middle Lower to upper Middle Devonian). However, in some intervals, such as Frasnian strata (lower Upper Devonian), group-level units are time-rock units, and formation-level units within groups are largely lithostratigraphic. Forty-eight years of research since Rickard’s (1975) New York Devonian correlation chart permits development of a new, more refined chart (forthcoming), and also permits a new synthesis of Devonian rocks and fossils in New York, presented in this work of twelve chapters, with additional digital appendices.

@article{doi1032857bap202340303,
    author = "Straeten, Charles Ver",
    title = "An introduction to the Devonian Period, and the Devonian in New York State and North America",
    year = "2023",
    journal = "Bulletins of American Paleontology",
    abstract = "The Devonian strata in New York State were the standard section for North America for over 100 years, and remain a significant reference for regional to global correlation and research. Since publication of L. V. Rickard’s (1975) New York Devonian correlation chart, various higher-resolution stratigraphic analyses have been employed, sometimes at bed-by-bed scale. These include sequence-, bio-, event-, chemo-, and other -stratigraphic approaches, along with increasingly finer-resolution geochronologic dating of airfall volcanic tephras. Results have led to many new interpretations and insights of the succession. The purpose of this three-volume work is to produce a new Devonian stratigraphic synthesis for New York State, and to record, often in detail, current knowledge of the succession, and various other geologic and paleontologic aspects of it for current and future research and discussion. The purpose of this chapter is to provide overviews of the Devonian Period, the Devonian of North America (“Laurentia”), the Devonian of eastern Laurentia, and the Devonian of New York State. Furthermore, this review extends beyond the sedimentary rock and paleobiological record, and beyond the United States, Canada, and northern Mexico, to also summarize aspects of Devonian orogenesis, metasedimentary foreland basin fill, silicic igneous activity, complexities of terranes of Mexico and Central America, and Appalachian faunas that extended into South America. The Devonian Period as a whole encompasses 60 million years of time, approximately 419 to 359 million years ago. During that time, shallow seas covered large continental areas; climate was warmer globally than our current climate, during the late stage of a global greenhouse climate. By the end of the Devonian, that warm climate was descending into a time of global icehouse conditions, with widespread glaciation. The positions of modern continental masses were much different. During the Devonian Period, Life first fully colonized the land, led by primitive spore-bearing plants, small arthropods, and apparently by the Middle Devonian, the first tetrapod (“four-legged”) animals, which evolved from bony fishes. Decimeter-tall plants at the beginning of the period had evolved to tree-size forms by the Middle Devonian, approximately 30 million years later, and Earth’s first forest ecosystems arose. Devonian strata are widespread around the ancient continent “Laurentia,” which approximately corresponds to modern North America). At that time, Laurentia straddled the equator, with New York State and the Appalachian region somewhat north of 30° south latitude. Shallow epicontinental seas covered large but varying amounts of the continent over the period. Mountain belts formed on the eastern, northern, and western margins of Laurentia, due to plate tectonic collisions with smaller continental masses, exotic terranes, and volcanic island arcs. Through the Early to Middle Devonian, seas in western and eastern Laurentia were separated by a “transcontinental arch,” and generally had distinctly different marine faunas. In the latest Middle Devonian, sea level transgressed over the land barrier of the Laurentian Transcontinental Arch and the Canadian Shield, and those marine faunas mixed, leading to a more global cosmopolitan fauna in the Late Devonian. Anomalously, however, Early and Middle Devonian Laurentian shallow marine faunas are found in Devonian rocks in Central and South America, which were part of the southern Gondwana continent, generally thought to be separated from Laurentia by oceanic water depths at that time. During the Devonian, eastern Laurentia was an active tectonic margin, related to continent-continent collisions with various terranes/smaller continental masses. The Caledonian, Acadian, and Neoacadian orogenies resulted in compressional and some transpressional tectonics, and the uplift of an extensive mountain belt from east Greenland to Alabama and Georgia. Crustal loading of the orogen in eastern Laurentia led to subsidence and formation of a retroarc Acadian-Neoacadian Foreland Basin, which was initially filled with marine waters, followed by gradual overfilling to above sea level by massive volumes of synorogenic sediments from the east. The resulting lands were the site of some of the earliest forests on Earth, preserved at several sites in New York State, and forest ecosystems. Large-scale deformation, seismic activity, and metamorphism in the mountain belt were accompanied by igneous processes, including explosive eruption of felsic volcanic ash and other material, collectively termed “tephra,” also sometimes termed ash or tuff layers, or if diagenetically altered, sometimes termed bentonite, K-bentonite, metabentonite, or tonstein layers. These explosive Devonian eruptions sent volcanic tephra high into the atmosphere, and easterly winds spread airfall volcanic “tephra layers” across the eastern United States. Meanwhile, rock decay in the mountains led to the erosion, transport, and deposition of massive volumes of clays, silt, sand, and gravel into the Acadian-Neoacadian Foreland Basin, and beyond. Devonian rocks in New York are found at or just below the surface across approximately 40\% of the state (\textasciitilde 50,500 km2/19,500 mi2). The strata are generally undeformed and gently dipping, and while often covered by soil, glacial sediments, and vegetative cover, are relatively widely found in natural and man-made exposures. Three relatively thin intervals of carbonates are accompanied by eastward thickening wedges of synorogenic mudrocks, sandstones, and minor conglomerates. The history of geological and paleontological observation and study in New York began in the late 18th century. The first professional geologists appeared in the early 19th century. Since the advent of the first geological survey of New York State in 1836, the Devonian Period (nearly termed the “Erian Period” for New York’s Devonian-age rocks) has been the focus of a great volume of research which continues today. The Devonian succession in New York includes strata from all seven stages of the period, with erosional gaps of small to major significance. In addition to a range of marine facies, nearly one quarter of the entire area of Devonian bedrock in the state was deposited in terrestrial settings, with massive volumes of siliciclastic sediments shed off of Acadian-Neoacadian highlands to the east, that also feature the fossils of Earth’s oldest known forest ecosystems. The stratigraphic philosophy in New York has long evolved toward a hybrid classification, wherein groups, formations, and bed-level units are largely time-rock/allostratigraphic to occasionally chronostratigraphic, with lithostratigraphy often ascribed to member-level divisions (e.g., Pragian to Givetian strata, middle Lower to upper Middle Devonian). However, in some intervals, such as Frasnian strata (lower Upper Devonian), group-level units are time-rock units, and formation-level units within groups are largely lithostratigraphic. Forty-eight years of research since Rickard’s (1975) New York Devonian correlation chart permits development of a new, more refined chart (forthcoming), and also permits a new synthesis of Devonian rocks and fossils in New York, presented in this work of twelve chapters, with additional digital appendices.",
    url = "https://www.semanticscholar.org/paper/00842e4432080af1d593e9bec5775e9cb270a7bc",
    doi = "10.32857/bap.2023.403.03",
    is_oa = "true",
    number = "403-404",
    pages = "11-102",
    semanticscholar_citation_count = "5",
    semanticscholar_id = "00842e4432080af1d593e9bec5775e9cb270a7bc"
}

@misc{crossref2024the,
    title = "The North American Continent",
    year = "2024",
    booktitle = "Geopolitics and Energy Transition 2",
    url = "https://doi.org/10.1002/9781394325528.ch1",
    doi = "10.1002/9781394325528.ch1",
    pages = "1-32"
}

In the Late Cretaceous, northern and southern hemispheres evolved distinct dinosaurian faunas. Titanosaurians and abelisaurids dominated the Gondwanan continents; hadrosaurids, ceratopsians and tyrannosaurs dominated North America and Asia. Recently, a lambeosaurine hadrosaurid, Ajnabia odysseus, was reported from the late Maastrichtian phosphates of the Oulad Abdoun Basin Morocco, suggesting dispersal between Laurasia and Gondwana. Here we report new fossils from the phosphates of Morocco showing lambeosaurines achieved high diversity in the late Maastrichtian of North Africa. A skull represents a new dwarf lambeosaurine, Minqaria bata. Minqaria resembles Ajnabia odysseus in size, but differs in the ventrally positioned jugal facet and sinusoidal toothrow. The animal is small, ~ 3.5 m long, but the fused braincase shows it was mature. A humerus and a femur belong to larger hadrosaurids, ~ 6 m long, implying at least three species coexisted. The diversity of hadrosaurids in Europe and Africa suggests a dispersal-driven radiation, with lambeosaurines diversifying to take advantage of low ornithischian diversity. African lambeosaurines are small compared to North American and Asia hadrosaurids however, perhaps due to competition with titanosaurians. Hadrosaurids are unknown from eastern Africa, suggesting Moroccan hadrosaurids may be part of a distinct insular fauna, and represent an island radiation.

@article{doi101038s41598024534479,
    author = "Longrich, Nicholas R. and Suberbiola, Xabier Pereda and Bardet, Nathalie and Jalil, Nour‐Eddine",
    title = "A new small duckbilled dinosaur (Hadrosauridae: Lambeosaurinae) from Morocco and dinosaur diversity in the late Maastrichtian of North Africa",
    year = "2024",
    journal = "Scientific Reports",
    abstract = "In the Late Cretaceous, northern and southern hemispheres evolved distinct dinosaurian faunas. Titanosaurians and abelisaurids dominated the Gondwanan continents; hadrosaurids, ceratopsians and tyrannosaurs dominated North America and Asia. Recently, a lambeosaurine hadrosaurid, Ajnabia odysseus, was reported from the late Maastrichtian phosphates of the Oulad Abdoun Basin Morocco, suggesting dispersal between Laurasia and Gondwana. Here we report new fossils from the phosphates of Morocco showing lambeosaurines achieved high diversity in the late Maastrichtian of North Africa. A skull represents a new dwarf lambeosaurine, Minqaria bata. Minqaria resembles Ajnabia odysseus in size, but differs in the ventrally positioned jugal facet and sinusoidal toothrow. The animal is small, \textasciitilde\ 3.5 m long, but the fused braincase shows it was mature. A humerus and a femur belong to larger hadrosaurids, \textasciitilde\ 6 m long, implying at least three species coexisted. The diversity of hadrosaurids in Europe and Africa suggests a dispersal-driven radiation, with lambeosaurines diversifying to take advantage of low ornithischian diversity. African lambeosaurines are small compared to North American and Asia hadrosaurids however, perhaps due to competition with titanosaurians. Hadrosaurids are unknown from eastern Africa, suggesting Moroccan hadrosaurids may be part of a distinct insular fauna, and represent an island radiation.",
    url = "https://doi.org/10.1038/s41598-024-53447-9",
    doi = "10.1038/s41598-024-53447-9",
    openalex = "W4391770790",
    references = "doi101016jgr201010005, doi101016jjsames2021103369, doi101371journalpone0175253, doi103390fossils2010001, doi104202app20110051, tsogtbaatar2019a"
}

@incollection{baruah2025continent,
    author = "Baruah, Shantanu",
    title = "Continent Page: North America",
    year = "2025",
    booktitle = "Generative AI for Full-Stack Development",
    url = "https://doi.org/10.1007/979-8-8688-2074-8\_10",
    doi = "10.1007/979-8-8688-2074-8\_10",
    pages = "161-176"
}

@article{doi101130abs2025am11277,
    author = "Brand, Harrison and Silverstein, Jessie and Adrian, Brent and Smith, Heather and Mohler, Benjamin",
    title = "Faunal diversity in Western North America during the Campanian and evidence for provincialism in Laramidian dinosaurs",
    year = "2025",
    journal = "Geological Society of America Abstracts with Programs",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://www.semanticscholar.org/paper/1edc04a6f45462bbcd2f3405c16de5cc95a38854",
    doi = "10.1130/abs/2025am-11277",
    is_oa = "true",
    semanticscholar_id = "1edc04a6f45462bbcd2f3405c16de5cc95a38854"
}

North America’s 1.1 Ga Midcontinent Rift preserves a remarkably complete record of Proterozoic continental rifting and large-scale magmatism. Here, we present new, high-precision U-Pb chemical abrasion−isotope dilution−thermal ionization mass spectrometry (CA-ID-TIMS) ages for the Ni-Cu-platinum group elements (PGE)−bearing Crystal Lake Intrusion and its feeder, the Mount Mollie dike. Our new data constrain the emplacement of the Crystal Lake Intrusion to 1092.9 ± 0.8 Ma and the Mount Mollie dike to 1094.0 ± 1.1 Ma. These ages place both within the final stages of a 1097−1092 Ma magmatic episode that followed the emplacement of the 1099 Ma Duluth Complex. This magmatic episode corresponds to a younger phase of rifting, marked by a pronounced reorganization of the rift axis from a northwest−southeast to a southwest−northeast orientation and the spatial focusing of magmatism into a narrow, structurally controlled corridor along the present-day northwestern shoreline of Lake Superior. This corridor, termed the North Shore Magmatic Feeder Zone, includes the Pigeon River and Mount Mollie dikes as well as the Beaver Bay Complex. It is interpreted as a deep-seated, magmatic pathway that fed the final major phases of Midcontinent Rift volcanism. The temporal overlap between this 1097−1092 Ma episode and the widespread magmatism of the Southwestern Laurentia large igneous province in the southwestern United States supports a broader geodynamic linkage across Laurentia during Mesoproterozoic plume activity. Our data indicate that the Crystal Lake Intrusion represents a dynamic, multiphase system formed by repeated pulses of magma. It was fed laterally by the large, composite Mount Mollie dike. Sulfide mineralization occurred during early volatile- and sulfur-saturated pulses, producing globular ores above older Logan sill rafts in the southern limb and massive sulfides in the northern limb via in situ contamination of sulfur-rich sediments. Distinct Cu/Zr and rare earth element patterns shared by both intrusions support derivation from a common, shallow, depleted-mantle source. This distinguishes them from earlier Midcontinent Rift intrusions. These findings emphasize that mineralization during the 1097−1092 Ma episode was largely restricted to intrusions emplaced into sulfur-bearing sedimentary basins, with the transition from dikes to sill-like geometries emerging as an important control on sulfide accumulation. The refined genetic and temporal framework presented here offers an improved basis for targeting Ni-Cu-PGE mineral systems in rift-related provinces. Moreover, our results reinforce the interpretation that late-stage Midcontinent Rift magmatism formed part of a broader, continent-scale phase of plume-influenced activity across Laurentia consistent with the timing of the Southwestern Laurentia large igneous province.

@article{doi101130b376491,
    author = "Smith, J. and Bleeker, W. and Hamilton, M.",
    title = "The 1093 Ma Crystal Lake Intrusion: A nickel-copper mineralized intrusion emplaced during the younger southwest−northeast rift phase of the Midcontinent Rift (North America)",
    year = "2025",
    journal = "Geological Society of America Bulletin",
    abstract = "North America’s 1.1 Ga Midcontinent Rift preserves a remarkably complete record of Proterozoic continental rifting and large-scale magmatism. Here, we present new, high-precision U-Pb chemical abrasion−isotope dilution−thermal ionization mass spectrometry (CA-ID-TIMS) ages for the Ni-Cu-platinum group elements (PGE)−bearing Crystal Lake Intrusion and its feeder, the Mount Mollie dike. Our new data constrain the emplacement of the Crystal Lake Intrusion to 1092.9 ± 0.8 Ma and the Mount Mollie dike to 1094.0 ± 1.1 Ma. These ages place both within the final stages of a 1097−1092 Ma magmatic episode that followed the emplacement of the 1099 Ma Duluth Complex. This magmatic episode corresponds to a younger phase of rifting, marked by a pronounced reorganization of the rift axis from a northwest−southeast to a southwest−northeast orientation and the spatial focusing of magmatism into a narrow, structurally controlled corridor along the present-day northwestern shoreline of Lake Superior. This corridor, termed the North Shore Magmatic Feeder Zone, includes the Pigeon River and Mount Mollie dikes as well as the Beaver Bay Complex. It is interpreted as a deep-seated, magmatic pathway that fed the final major phases of Midcontinent Rift volcanism. The temporal overlap between this 1097−1092 Ma episode and the widespread magmatism of the Southwestern Laurentia large igneous province in the southwestern United States supports a broader geodynamic linkage across Laurentia during Mesoproterozoic plume activity. Our data indicate that the Crystal Lake Intrusion represents a dynamic, multiphase system formed by repeated pulses of magma. It was fed laterally by the large, composite Mount Mollie dike. Sulfide mineralization occurred during early volatile- and sulfur-saturated pulses, producing globular ores above older Logan sill rafts in the southern limb and massive sulfides in the northern limb via in situ contamination of sulfur-rich sediments. Distinct Cu/Zr and rare earth element patterns shared by both intrusions support derivation from a common, shallow, depleted-mantle source. This distinguishes them from earlier Midcontinent Rift intrusions. These findings emphasize that mineralization during the 1097−1092 Ma episode was largely restricted to intrusions emplaced into sulfur-bearing sedimentary basins, with the transition from dikes to sill-like geometries emerging as an important control on sulfide accumulation. The refined genetic and temporal framework presented here offers an improved basis for targeting Ni-Cu-PGE mineral systems in rift-related provinces. Moreover, our results reinforce the interpretation that late-stage Midcontinent Rift magmatism formed part of a broader, continent-scale phase of plume-influenced activity across Laurentia consistent with the timing of the Southwestern Laurentia large igneous province.",
    url = "https://www.semanticscholar.org/paper/3d098e3999ffcb992d657175a992dc4c0acfc439",
    doi = "10.1130/b37649.1",
    is_oa = "true",
    number = "3-4",
    pages = "1419-1438",
    semanticscholar_id = "3d098e3999ffcb992d657175a992dc4c0acfc439",
    volume = "138"
}