See more from this Division: Topical Sessions
See more from this Session: Paleontological and Sedimentological Consequences of Calcite and Aragonite Sea Dynamics
Abstract:
The evaluation of controlling factors of carbonate platform evolution requires a precise stratigraphy. We have studied carbonate platforms in the Mediterranean Tethys and Middle East, and established a high resolution stratigraphy of platform evolution based on carbon isotope and strontium isotope chemostratigraphy. Many platforms drowned before, during, or shortly after OAEs. Those platforms that survived went through a stage of microbial carbonate production during OAE 1a and OAE 2, but aragonite-dominated carbonate production resumed after OAE 1a in the Middle East, forming the prolific caprinid rudist buildups of the Shuaiba Formation. Extinction of the caprinids in the Middle East occurred during subaerial exposure that terminated platform aggradation at the Early/Late Aptian boundary, about two million years after OAE1a.
Our data suggest that the repeated demise of aragonite dominated carbonate production during the mid-Cretaceous period of an exceptionally low seawater Mg/Ca ratio is linked to changes in sea level and possibly climate. Mid-Cretaceous OAEs may have additionally stressed important groups of carbonate producers, but were not the major cause of platform drowning and extinction among major carbonate producers.
See more from this Division: Topical Sessions
See more from this Session: Paleontological and Sedimentological Consequences of Calcite and Aragonite Sea Dynamics