--> The Catchment-Integrated Response to Rapid Climatic Warming During the Paleocene-Eocene Thermal Maximum: Wilcox and Claiborne Groups, Gulf Coast U.S.A.

AAPG ACE 2018

Datapages, Inc.Print this page

The Catchment-Integrated Response to Rapid Climatic Warming During the Paleocene-Eocene Thermal Maximum: Wilcox and Claiborne Groups, Gulf Coast U.S.A.

Abstract

Downstream, distal stratigraphy can provide a critical, integrated perspective on the catchment-wide response of a sediment routing system to external and/or autogenic processes. The Wilcox Group and overlying Claiborne Group found along the Gulf Coast, USA, contain Paleocene to middle Eocene strata deposited during a period of known global climate change. The Paleocene-Eocene Thermal Maximum (PETM) is a well-known hyperthermal that is shown to correlate with a basin-wide shift to multistoried sandstone sheets containing upper flow regime sedimentary structures in upstream Laramide basins. However, the position of the PETM within downstream Gulf Coast stratigraphy and the effect that this hyperthermal may have had on sedimentation are poorly constrained, despite the potential linkage with the down-dip, petroliferous Wilcox play in the outboard Gulf of Mexico.

We examined sediment from two east Texas cores, located approximately 50 km apart, and collected samples for isotopic analysis of bulk organic carbon to identify the location of the PETM. The first core contains a nearly continuous record of the Paleocene Wilcox Group, including the upper Paleocene Calvert Bluff Formation. The second well extends continuously from the uppermost Calvert Bluff Formation through the lower Eocene Carrizo Formation and into the overlying Reklaw Formation. Deposits in both cores are interpreted as a mixture of continental-fluvial and shallow-marine deposits of tidally modified channels, tidal flats, swamps, and pedogenically modified sediments. Bulk organic carbon isotopic data show a major negative excursion, typical of the PETM, either near the base of the Carrizo Formation (Well 1) or within the base of the Carrizo Formation itself (Well 2). The second well also records a subsequent carbon isotope recovery over ~25m within the lower half of the Carrizo Formation. We hypothesize that the pronounced negative carbon isotope excursion could represent the PETM, suggesting that the sand-rich deposits of the Carrizo Formation may be causally linked with the global PETM climatic event. If correct, the Carrizo Formation may record a major pulse of coarser-grained sediment that reflects the integrated response of central North America to rapid climatic warming during the PETM, with implications for the role of climate change in shaping clastic reservoir distribution in petroleum-bearing basins.