Geological Society of America

T283 Greenhouse to Icehouse Transition: Global Events of the Devonian, Carboniferous, and Early Permian II

Wednesday, 7 November 2018
1:30 PM - 5:30 PM
Room 140

CARBONIFEROUS CLIMATE TELECONNECTIONS ARCHIVED IN COUPLED BIOAPATITE δ18OPO4 AND 87SR/86SR, DONETS BASIN, UKRAINE

Paper number: T283-1
Program: Technical Sessions
Time: 1:30 PM – 1:45 PM

Authors

Isabel Montanez Presenting Author
University of California, Davis, Davis, CA
Dillon J. Osleger
University of California Santa Barbara, Santa Barbara, CA
Jitao Chen
CAS Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing
Barbara E. Wortham
University of California, Davis, Davis, CA
Robert G. Stamm
Eastern Geology and Paleoclimate Science Center, Reston, VA
Tamara I. Nemyrovska
National Academy of Sciences of Ukraine, Kiev
Julie M. Griffin
California State University Sacramento, Sacramento, CA
Vladislav I. Poletaev
National Academy of Sciences of Ukraine, Kiev
Bruce R. Wardlaw
Eastern Geology and Paleoclimate Science Center, Reston, VA

Abstract

There is growing evidence for geographic and temporal variability in the environmental conditions of semi-restricted epicontinental seas that leads to the decoupling of their seawater isotopic signatures from those of the open ocean. Here we present conodont apatite δ¹⁸O_PO4 and ⁸⁷Sr/⁸⁶Sr records spanning 24 Myr of the Late Mississippian through Pennsylvanian derived from the U-Pb calibrated cyclothemic succession of the Donets Basin, eastern Ukraine. Systematic fluctuations in bioapatite δ¹⁸O_PO4 and ⁸⁷Sr/⁸⁶Sr broadly follow major shifts in the Donets onlap-offlap history and inferred regional climate, but are distinct from a contemporaneous more open-water δ¹⁸O_PO4recordfrom South China and from the global seawater Sr isotope trend.

An up to 6‰ negative offset in Donets δ¹⁸O_PO4 values from those of more open-water conodonts and greater temporal variability in δ¹⁸O_PO4 and ⁸⁷Sr/⁸⁶Sr records are interpreted to primarily record climatically driven changes in local environmental processes in the Donets sea. Systematic isotopic shifts associated with Myr-scale sea-level fluctuations, however, indicate an extrabasinal driver. We propose a mechanistic link to glacioeustasy through a teleconnection between high-latitude ice changes and atmospheric pCO₂ and regional monsoonal circulation in the Donets region. Inferred large-magnitude changes in Donets seawater salinity and temperature, not archived in the more open-water or global contemporaneous records, indicate a modification of the global climate signal in the epicontinental sea through amplification of the climate signal by local and regional environmental processes. This finding of global climate change filtered through local processes has implications for the use of conodont δ¹⁸O_PO4 and ⁸⁷Sr/⁸⁶Sr values as proxies of paleo-seawater composition, sea-surface temperatures, and magnitudes of glacioeustasy.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-320584

© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.