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ABSTRACT: Tectonic and Eustatic Control on the Evolution of the Maldives Carbonate Platform from Eocene to Present

Belopolsky, Andrei V., and André W. Droxler , Rice University, Houston, TX

The Maldives is a large (800 km long, up to 130 km wide) isolated carbonate platform in the equatorial Indian Ocean. The interpretation of Shell 6000 km 2-D seismic data set, combined with the data from two industrial wells and two ODP sites, allows to reconstruct the entire evolution of the platform. The volcanic basement of the late Paleocene age is cut by two deep, narrow grabens containing up to 4 km of sediments. In the early Eocene, carbonate platforms were established on the topographic highs. The graben faults were active until the late early Oligocene. Carbonate platforms continued to accrete through the Eocene and Oligocene but a series of deeper seaways with periplatform sedimentation existed in grabens-controlled areas.

A sea level fall in late-early Oligocene exposed the tops of the carbonate platforms. The platforms recovered and the late Oligocene platforms had well-defined rims and shallow interior lagoons. During the Oligocene/Miocene transition the platform interiors drowned while the platform rims kept up with the rising sea level, creating a characteristic "empty bucket" geometry. Where possible, the reefs backstepped and migrated upslope creating a series of flat top banks on the periphery of the basin. The banks progradated towards the central part of the basin in middle Miocene. In the late Miocene and Pliocene, the central part of the basin experienced basinal aggradation. The present day atoll configuration is explained by the rapid sea level falls and rises that periodically exposed and flooded the flat-topped carbonate banks during the Pleistocene.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia