Silurian Shelf Sequences, Wabash Platform, Mid-Continent North America: Records Of Global Climate Change

Alison Spengler,

Virginia Polytechnic Institute and State University, Department of Geosciences,

Blacksburg, VA,

[email protected].

Global climate and amount of polar ice has an impact on the stacking patterns of carbonate parasequences and sequences during deposition. Platforms formed under greenhouse conditions should show evidence of small high frequency sea level changes of low amplitude, if shallow, or even non-cyclic subtidal successions, where water depths are below the influence of the sea level fluctuations. In contrast, with increasing amounts of ice, waxing and waning of ice sheets is likely to cause significant sea level changes that should be reflected in the sedimentary pile. Such glacio-eustasy can significantly affect the compartmentalization of potential reservoirs of the accumulating sedimentary succession. The late Ordovician and Early Silurian were characterized by significant glacial pulses, which apparently waned into the later Silurian. This research will focus on documenting detailed sequence and parasequence stacking patterns on the mid-continent Silurian Wabash Platform to evaluate the effects of glacio-eustacy on the accumulating sedimentary succession. It will also compare the successions to those in the Appalachians and the western U.S. The field data will be used with computer modeling to evaluate which phases of the Silurian are compatible with times of moderate ice on Gondwana versus a greenhouse ice-free world.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid