GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 114-1
Presentation Time: 8:15 AM


SCHMITZ, Mark D., Department of Geosciences, Boise State University, 1910 University Drive, Boise, ID 83725 and DAVYDOV, Vladimir, Department of Geosciences, Boise State University, USA and Kazan Federal University, Russia, 1910 University Drive, Boise, ID 83725,

A quantitative biostratigraphic and radiometric calibration has been presented for the Pennsylvanian through Early Permian global time scale, based upon high-precision, isotope dilution–thermal ionization mass spectrometer (ID-TIMS) U-Pb zircon ages for interstratified ash beds in the parastratotype sections of the southern Urals of Russia, and in the cyclic, paralic successions of the Donets Basin of Ukraine. Twenty-four ash bed ages in three outer ramp and basinal sections of the Pre-Uralian foredeep bracket the biotic definitions of global stages and regional substages from the base of the Upper Pennsylvanian Kasimovian Stage to the base of the Lower Permian Artinskian Stage; four additional ash bed ages in two sections of the eastern slope of the Urals constrain the global Bashkirian and Serpukhovian Stages. Twelve ash beds ages constrain and tune the Middle to Late Pennsylvanian fourth-order sequences of the Donets basin. Quantitative stratigraphic methods (CONOP9) were applied to a compilation of over 5000 bio-events in 35 stratigraphic sections supplemented by our dated volcanic horizons to refine the Pennsylvanian–Early Permian global time scale. Significant shifts in the duration of several stages result, ranging from one to six million years, compared with prior estimates. The unprecedented density of radiometric calibration points for the Pennsylvanian–Permian transition provides a high-resolution (~0.1-Ma) global chronostratigraphic standard for testing and improving biostratigraphic correlations across Euramerica. We have integrated radiometric ages, biostratigraphic correlation, and cyclostratigraphic tuning of major cyclothems to the long-period (404-ka) eccentricity cycle to elucidate the tempo, magnitude, and forcing of eustatic changes and cyclothemic deposition associated with the waxing and waning of Gondwanan ice sheets, and establish a pan-Euramerican chronostratigraphic framework for most of Pennsylvanian and Early Permian time. This refined time scale is integral to understanding the relationship between tectonic forcing, mountain building, basin development, and associated global climatic and ecological changes during the Late Paleozoic Ice Age.