Collaborative Research: High-Precision U-Pb Zircon Geochronology of the Late Triassic Chinle Fluvial System of the Colorado Plateau

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Collaborative Research: High-Precision U-Pb Zircon Geochronology of the Late Triassic Chinle Fluvial System of the Colorado PlateauSamuel Bowring, MIT, EAR-1024196David Fastovsky, Univ. Rhode Island, EAR-1023788 ABSTRACTPIs propose a program of high-precision U-Pb zircon geochronology on tuffaceous rocks preserved in the Late Triassic Chinle Formation of the southwestern United States. The Chinle is a fluvial sedimentary sequence that preserves a rich fossil record that reveals the ascendancy of dinosaur faunas and the shaping of the modern biota. Reconstructing the tempo and mode of paleoenvironmental and biotic evolution recorded in the Chinle, however, has been problematic. This is largely because although a detailed lithostratigraphy and biostratigraphy have been constructed, they are not well calibrated geochronologically. High-resolution isotopic dating of key fossiliferous Chinle outcrops, such as PIs propose, would allow the wealth of information that it contains to be integrated into the global Triassic timescale. The Chinle preserves a unique record of terrestrial biotic evolution and paleoclimate in a critical time interval of Earth history. Its sequential biostratigraphic assemblages, codified as Land Vertebrate Faunachrons, are core to the understanding of the early dinosaur evolution during a period of remarkable environmental change. Proposed high-precision temporal calibration of the Chinle litho- and bio-stratigraphy will greatly enhance their utility and will allow their integration into the global late Triassic time scale. EARTHTIME standards and tracer solutions will be used facilitating comparison between labs. The work proposed is associated with a national park with the potential of exposing an estimated 500,000 visitors per year from a wide spectrum of people to the results of this study in the form of interpretive exhibits and literature. PIs are also committed to the education of Native American communities who inhabit the land which is in part the subject of the research.