Abstract: Paleotectonic and Paleoclimatic Interpretations of Oligocene Shallow Water Carbonates
STOKLOSA, MICHELLE LEE, University of Wisconsin-Madison, Department of Geology and Geophysics, Madison, WI
The Oligocene is characterized by abrupt global cooling events and major changes in ocean chemistry, sedimentation, and biogeography that resulted from the opening and closing of multiple seaways. These changes have been documented in the deep oceans and continent interiors, but rarely on shallow-water carbonate platforms. The purpose of this project is to investigate the effects of these Oligocene global changes on shallow-water carbonates through the study of a platform in southeast Spain and cores drilled in southern Australia.
Preliminary work has shown that excellent exposures of shallow- to deep-water Oligocene-Miocene strata exist in the foothills of the Betic Mountains in Alicante, southeast Spain. The succession exhibits a basin-to-shelf transition of a prograding carbonate platform followed by drowning and subsequent transgression of shales and glauconite-rich sands; this change in sedimentation probably reflects the transition of tectonic settings from a passive margin to foreland basin. Mapping and detailed sedimentologic/stratigraphic work on this strata would be done to characterize the architecture of this platform and reconstruct its depositional history. A comparison of isotopic data from the basinal section to ODP-recognized events would allow interpretation of shallow-water architectural elements by means of physical correlation.
ODP Leg 182 will drill the Australian Bight where a southern hemisphere coolwater Oligocene succession exits. A proposal for post-cruise sampling of the Oligocene platform will be submitted with the goal of describing sediments and faunal types, and analyzing isotopes in order to tie the faunal and facies changes to the deep water isotopic record.
AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid