GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 220-1
Presentation Time: 1:30 PM


SUAREZ, Celina1, KOHN, Matthew J.2, SUAREZ, Marina B.3, TRAVIS TAYLOR, Leah M.4, YAMAMURA, Daigo5, JACKSON, Thea1, OBERG, Danielle1, PARK BOUSH, Lisa E.6, MINZONI, Rebecca Totten4, TITUS, Alan7, TOMPKINS, Tristan1, FRUCCI, Mason N.8 and ANTONIETTO, Lucas S.9, (1)Geosciences, University of Arkansas, 216 Gearhart Hall, Fayetteville, AR 72701, (2)Department of Geosciences, Boise State University, 1910 University Drive, Boise, ID 83725-1535, (3)Department of Geology, University of Kansas, 1414 Naismith Drive, Lawrence, KS 66045, (4)Department of Geological Sciences, University of Alabama, 201 7th Street, Tuscaloosa, AL 35487, (5)Department of Geoscience, University of Arkansas, 216 Gearhart Hall, Fayetteville, AR 72701, (6)Department of Geosciences, University of Connecticut, 354 Mansfield Road U-1045, Storrs, CT 06269, (7)Bureau of Land Management, Grand Staircase-Escalante National Monument, 669 S. Highway 89A, Kanab, UT 84741, (8)Department of Geosciences, Baylor University, Waco, TX 76798, (9)Center for Integrative Geosciences, University of Connecticut, 354 Mansfield Road, Unit 1045, Beach Hall, Room 244, Storrs, CT 06269

Detection of authigenic or biogenic isotope and elemental signals in ancient materials have been sought after for decades. The goal of such studies are to provide parameters such as seasonality trends, mean annual precipitation, paleotemperatures, and CO2 concentrations or to provide specific biological or behavioral information such as migration routes. Although some work suggests ancient signals have been obliterated by diagenetic alteration, careful analysis via trace element, isotopic, microscopy, and spectroscopic work suggests original signals can be detected if careful analysis is taken. Detection of diagenesis can be determined via multi-proxy investigation or via pilot studies of multi-taxon assemblages. For example, petrographic, isotopic, and trace element analysis of fossil bone reveals a fossilization front in Pleistocene bone from Idaho Falls while a Cretaceous bone shows complete recrystallization of both phosphatic and carbonate isotopes to diagenetic equilibrium values. Multi-taxon assemblages from the Kaiparowits and Cedar Mountain formations of Utah and the Mooreville Chalk reveal discrete separation of taxa in C-O-isotope space and in the δ18Op composition respectively based on ecology that suggest biogenic stable isotopic composition. Likewise, careful thin section work suggests that original meteoric calcite lines can be determined from pedogenic carbonate nodules as old as 201 million years and 100 million years. Finally, stable isotopic analysis of ostracods reveals both diagenetic and biogenic information when carefully analyzing internal steinkern molds versus valves. These examples suggest that careful screening of fossil samples or pilot studies can detect biogenic signals in material as old as 200 million years old and possibly older. With new instrumentation in the pipelines and new chemical systems being investigated, it is an exciting time for “paleobiogeochemists.”