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A Multi-Proxy Approach to Determining Basin Architecture and Facies Distribution: Integrating Sequence Stratigraphy, Biostratigraphy, and Chemostratigraphy

Nicholas B. Sullivan
Wisconsin Geological and Natural History Survey

The lower Silurian successions of eastern North America provide a crucial laboratory for the development of stratigraphic methodologies. Although this record of Earth history is represented by extensive exposures and a long history of investigation, the temporal and stratigraphic resolution of this system has been hindered by a scarcity of biostratigraphically useful taxa, pervasive dolomitization, and a historical tendency toward geographically restricted case studies. However, a wealth of data, generated from a variety of methods, brings the promise of a high-resolution depositional framework for these units within reach. New and published information is synthesized herein, and a refined depositional framework for these strata is summarized.

New conodont data recovered from several of these sections, and a growing body of δ13Ccarb data can be utilized to provide chronostratigraphic control through recognition of diagnostic faunal assemblages and discrete carbon isotope excursions. Constrained by this information, several distinct packages of strata and marker beds can be identified with confidence, and traced for hundreds of miles across the basin. Many of these beds contain abundant authigenic minerals and overlie regionally angular unconformities. These horizons are interpreted as transgressive deposits bracketing highstand shales and siltstones. At least three major depositional sequences can be identified and characterized, providing a context for understanding the distribution of unusual facies, and establishing a testable sequence stratigraphic framework that may serve as a basis for future investigations.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013