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Abstract: Testing the Global Nature of Neogene Sea Level Events, Using Sequence Stratigraphy and Computer Simulations.

SEN, ANIMIKH, and CHRISTOPHER G. St. C. Kendall, University of South Carolina; & Andrei Belopolsky, and ANDRE DROXLER, Rice University.

The Neogene portion of the global sea level cycle chart of Haq, updated with new ages from the Berggren time scale, was input into a sedimentary simulation program to model the development of prograding wedges seen in a seismic section from the Western Bahamas. The simulation (Figure 1) produced a remarkable match with the seismic section (Figure 2) when a near uniform rate of sedimentation and constant rate of tectonic subsidence rate were maintained and sea level was the only variable. The ages of the third order sequence boundaries, determined from the sea level curve, in most cases closely matched to the initial results of the Bahamas Drilling Project. This confirms both that the carbonates are sensitive to the sea essentially correct.level fluctuations and that the events on the Haq et al curve are essentially correct.

The global nature of these Neogene sea level events was confirmed on seismic sections from Offshore Western Australia and the Maldives. These have similar lithology (carbonate) and geometry (prograding wedges) to the Bahamas. Initial results from the Australian section indicates that a match between simulation and seismic required an overprint of tectonic movement on sediment deposition. In the Maldives archipelago, which since the Oligocene had a relatively quiescent tectonic history, the sea level cycles match those of the Haq sea level curve. This documents that forward computer modeling, using simple geometric rules, can be used to solve complex problems and that the Haq sea level chart can be assumed to be an accurate record of Neogene sea level history.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah