Environmental Conditions During Recovery from the End-Permian Extinction: Comparative Analysis of Carbon Isotope Data from China, Japan, and Turkey
Rachelle A. Kernen1, David Follett1, Mitch Nothem1, Mindi Summers2, Ellen Schaal2, Jon Payne2, and Dan Lehrmann1
1Geology, Univeristy of Wisconsin Oshkosh, Oshkosh, WI
2School of Earth Sciences, Stanford University, Stanford, CA
The goal is to use high resolution geochemical and paleonlologic data to evaluate the impact of oceans and atmosphere chemistry change on biologic recovery following the end-Permian mass extinction.
High-resolution sampling from Japan and Turkey reveals a carbon isotope stratigraphy similar to previous studies from South China. Carbon isotope excursions from Japan and Turkey exhibit a similar pattern of high-amplitude excursions beginning at the Permian-Triassic boundary and ending with a large excursion in the earliest Middle Triassic (Anisian). Stabilization of the carbon isotope signal is nearly identical to that described from South China. Differences in magnitudes and number of excursions between Japan, Turkey, and South China can be explained by different stratigraphic completeness or local oceanographic conditions. 87Sr/86Sr data from Turkey and south China are consistent with previous studies in exhibiting a large positive excursion from 0.7068 near the Permian-Triassic boundary to to 0.7082 at the base of the Middle Triassic. Foraminifera size and diversity rapidly increased after carbon-cycle stabilization.
Carbon isotope excursions can be explained by methane clathrate release or thermogenic methane release associated with Siberian traps volcanism. Our study supports the later hypothesis because methane clathrate regeneration takes place at time scales too extensive to account for these changes. Thermogenic methane release during the Early Triassic drove repeated negative carbon isotope excursions, fueled accelerated silicate weathering on land and delayed biotic recovery through impacts on climate and ocean chemistry. Intervening positive carbon excursions may have been driven by increased oceanic carbon burial driven by pulses of ocean anoxia linked to climate fluctuations or changes in carbon burial in river delta systems.
AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas