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The Laramide Caborca orogenic gold belt of northwestern Sonora, Mexico; white mica 40Ar/39Ar geochronology from gold-rich quartz veins The Laramide Caborca orogenic gold belt of northwestern Sonora, Mexico; white mica 40Ar/39Ar geochronology from gold-rich quartz veins
Introduction This report contains reduced 40Ar/39Ar geochronological data from 63 hydrothermal white mica samples separated from orogenic gold-rich quartz veins in the Laramide Caborca orogenic gold belt (COGB) of northwestern Sonora, Mexico. The main objective of this report is to present the sample locations, 40Ar/39Ar experimental methodology, and 40Ar/39Ar isotopic data. We include...
Authors
Aldo Izaguirre, Michael J. Kunk, Alexander Iriondo, Ryan J. McAleer, Juan Antonio Caballero-Martinez, Enrique Espinosa-Aramburu
Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils
Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and...
Authors
Claire C. Treat, Miriam C. Jones, P. Camill, A. Gallego-Sala, M. Garneau, Jennifer W. Harden, G. Hugelius, E.S. Klein, Ulla Kokfelt, P. Kuhry, Julie Loisel, J.H. Mathijssen, J.A. O'Donnell, P.O. Oksanen, T.M. Ronkainen, A. B. K. Sannel, J. J. Talbot, C.M. Tarnocal, M. Valiranta
Erosional and depositional history of the Atlantic passive margin as recorded in detrital zircon fission-track ages and lithic detritus in Atlantic Coastal plain sediments Erosional and depositional history of the Atlantic passive margin as recorded in detrital zircon fission-track ages and lithic detritus in Atlantic Coastal plain sediments
Comparison of fission-track (FT) ages of detrital zircons recovered from Atlantic Coastal Plain sediments to FT ages of zircons from bedrock in source terranes in the Appalachians provides a key to understanding the provenance of the sediments and, in turn, the erosional and depositional history of the Atlantic passive margin. In Appalachian source terranes, the oldest zircon fission...
Authors
C. W. Naeser, N.D. Naeser, Lucy E. Edwards, Robert E. Weems, C. Scott Southworth, Wayne L. Newell
Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA
Heavily tuberculated glyptosaur osteoderms were collected in an active limestone quarry in northern Berkeley County, South Carolina. The osteoderms are part of a highly diverse late Paleocene vertebrate assemblage that consists of marine, terrestrial, fluvial, and/or brackish water taxa, including chondrichthyan and osteichthyan fish, turtles (chelonioid, trionychid, pelomedusid, emydid)
Authors
David J. Cicimurri, James L. Knight, Jean Self-Trail, Sandy M. Ebersole
Stratigraphic revision of the Cooper Group and the Chandler and Edisto Formations in the Coastal Plain of South Carolina Stratigraphic revision of the Cooper Group and the Chandler and Edisto Formations in the Coastal Plain of South Carolina
No abstract available.
Authors
Robert E. Weems, Barry Albright, Laurel M. Bybell, David J. Cicimurri, Lucy E. Edwards, W. Burleigh Harris, William C. Lewis, Jason E. Osborne, Albert E. Sanders, Jean Self-Trail
Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation Evidence for an ice shelf covering the central Arctic Ocean during the penultimate glaciation
The hypothesis of a km-thick ice shelf covering the entire Arctic Ocean during peak glacial conditions was proposed nearly half a century ago. Floating ice shelves preserve few direct traces after their disappearance, making reconstructions difficult. Seafloor imprints of ice shelves should, however, exist where ice grounded along their flow paths. Here we present new evidence of ice...
Authors
Martin Jakobsson, Johan Nilsson, Leif G. Anderson, Jan Backman, Goran Bjork, Thomas M. Cronin, Nina Kirchner, Andrey Koshurnikov, Larry Mayer, Riko Noormets, Matthew O’Regan, Christian Stranne, Roman Ananiev, Natalia Barrientos Macho, Dennis Cherniykh, Helen Coxall, Bjorn Eriksson, Tom Floden, Laura Gemery, Orjan Gustafsson, Kevin Jerram, Carina Johansson, Alexey Khortov, Rezwan Mohammad, Igor Semiletov
Metaultramafic schists and dismembered ophiolites of the Ashe Metamorphic Suite of northwestern North Carolina, USA Metaultramafic schists and dismembered ophiolites of the Ashe Metamorphic Suite of northwestern North Carolina, USA
Metaultramafic rocks (MUR) in the Ashe Metamorphic Suite (AMS) of northwestern North Carolina include quartz ± feldspar-bearing QF-amphibolites and quartz-deficient, locally talc-, chlorite-, and/or Mg-amphibole-bearing TC-amphibolites. Some workers divide TC-amphibolites into Todd and Edmonds types, based on mineral and geochemical differences, and we provisionally add a third type –...
Authors
Loren A. Raymond, Arthur J. Merschat, R. Kelly Vance
Paleogeographic implications of Late Miocene lacustrine and nonmarine evaporite deposits in the Lake Mead region: Immediate precursors to the Colorado River Paleogeographic implications of Late Miocene lacustrine and nonmarine evaporite deposits in the Lake Mead region: Immediate precursors to the Colorado River
Thick late Miocene nonmarine evaporite (mainly halite and gypsum) and related lacustrine limestone deposits compose the upper basin fill in half grabens within the Lake Mead region of the Basin and Range Province directly west of the Colorado Plateau in southern Nevada and northwestern Arizona. Regional relations and geochronologic data indicate that these deposits are late...
Authors
James E. Faulds, Charlotte Schreiber, Victoria E. Langenheim, Nicholas H. Hinz, Tom Shaw, Matthew T. Heizler, Michael E Perkins, Mohammed El Tabakh, Michael J. Kunk
Structural geometry of the Valley and Ridge and Plateaus provinces Structural geometry of the Valley and Ridge and Plateaus provinces
The Valley and Ridge physiographic province comprises the area between the Blue Ridge province on the east and the Appalachian Plateau province on the west. The province consists of Paleozoic carbonate and clastic rocks that were folded and thrust faulted during the Alleghanian orogeny. The Appalachian Plateau province consists of mostly flat lying to gently dipping upper Paleozoic rocks...
Authors
Mark A. Evans, Randall C. Orndorff, William S. Henika
Awell-preserved conodont fauna from the Pennsylvanian Excello Shale of Iowa, U. S. A. Awell-preserved conodont fauna from the Pennsylvanian Excello Shale of Iowa, U. S. A.
A superbly preserved discrete element conodont fauna has been recovered from carbonate concretions from the upper Desmoinesian (Pennsylvanian) Excello Shale at two localities in south-central Iowa. The multielement apparatuses for Gondolella wardlawi (new species), Idiognathodus acutus, Idioprioniodus conjunctus, and Neognathodus roundyi are reconstructed. Rare specimens of Idiognathodus...
Authors
Merlynd K. Nestell, Bruce R. Wardlaw, John P. Pope
Reply Zalasiewicz et al. comment Reply Zalasiewicz et al. comment
No abstract available.
Authors
Stanley C. Finney, Lucy E. Edwards
Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus ocean, Blue Ridge, VA–NC–TN Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus ocean, Blue Ridge, VA–NC–TN
Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock formations, the northeast end of the Mountain City window, the separation of Mesoproterozoic rocks of the Blue Ridge into three age groups, and...
Authors
Arthur J. Merschat, C. Scott Southworth, Christopher S. Holm-Denoma, Ryan J. McAleer