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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 48 (1998), Pages 487-497

Carbonate Cycles in Upper Cretaceous (Campanian) Demopolis Chalk, West-Central Alabama

Jeffrey D. Warren (1), Charles E. Savrda (2)

ABSTRACT

Carbonate and organic (TOC, Previous HitpalynofaciesTop, and pyrolysis) analyses of the Upper Cretaceous (Campanian) Demopolis Chalk in western Alabama were undertaken to assess the character and origin of decimeter-scale carbonate rhythms expressed therein. Stratofabric and spectral analyses of carbonate time series indicate that depositional cyclicity was controlled by climate perturbations induced by all three Milankovitch orbital parameters (eccentricity, precession, and obliquity). Modeling of changes in total sediment and organic accumulation rates with changes in carbonate content, along with other organic evidence, indicate that carbonate rhythms were caused by climate-mediated variations in clastic sediment delivery to the Gulf margin (i.e., dilution cycles).


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