Southeastern Section - 63rd Annual Meeting (10–11 April 2014)

Paper No. 2
Presentation Time: 1:20 PM


IRMIS, Randall B., Natural History Museum of Utah and Department of Geology & Geophysics, University of Utah, 301 Wakara Way, Salt Lake City, UT 84108-1214, MUNDIL, Roland, Berkeley Geochronology Center, 2455 Ridge Rd, Berkeley, CA 94709-1211, GEHRELS, George E., Arizona LaserChron Center, Department of Geosciences, University of Arizona, Tucson, AZ 85721, GEISSMAN, John W., Department of Geosciences, University of Texas at Dallas, 800 W. Campbell Rd, ROC21, Richardson, TX 75080, KENT, Dennis V., Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854, OLSEN, Paul E., Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964-1000, WHITESIDE, Jessica H., Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, SO17 1BJ, United Kingdom and PARKER, William G., Division of Resource Management, Petrified Forest National Park, P.O. Box 2217, 1 Park Rd, Petrified Forest, AZ 86028,

Continental-scale comparisons of Late Triassic non-marine sedimentary archives have been hampered by the lack of biostratigraphically-independent age constraints. A major step forward was provided by the Newark Astronomically-calibrated Geomagnetic Polarity Time Scale (Newark APTS) from the predominantly lacustrine Newark Basin of eastern North America, which was further calibrated using high-resolution U-Pb CA-TIMS ages bracketing the Triassic-Jurassic boundary in the same sequence. In contrast, similar age control for non-marine sediments in western North America has been lacking. New U-Pb CA-TIMS ages from the fluvial Chinle Formation of Arizona and New Mexico, along with previously published magnetostratigraphic records, allow age-constrained paleoenvironmental and biotic comparisons across the North American continent for the first time. These data demonstrate that whereas the Newark Supergroup Late Triassic record extends from the Carnian to the end of the Rhaetian, the Chinle Formation is restricted to the Norian-Rhaetian. These age constraints, combined with paleogeographic data, suggest that unlike some tropical paleoequatorial eastern North America records, the western North America deposits were almost wholly between 5-15°N with a semi-arid climate, which may explain the absence of traversodont cynodont synapsids in western North America. Penecontemporaneous Norian vertebrate assemblages from eastern and western North America reveal no unambiguous overlap at the species level, and only a handful of shared taxa at the genus level, supporting previous conclusions of distinct biotic provinciality. More refined comparisons, such the examination of the potential biotic and environmental effects of the mid-Norian Manicouagan bolide impact, require sub-million year resolution. This precision is achievable through integration of the Newark APTS with the dense paleomagnetic and radioisotopic sampling of Chinle Formation strata from the recently recovered Petrified Forest National Park core of the NSF/ICDP-funded Colorado Plateau Coring Project. The resulting chronostratigraphic framework will be integrated with other terrestrial records and directly correlated with marine records in order to scrutinize causality and the spatial extent of paleoenvironmental signals.