--> Abstract: Seismic Geomorphology of Fluvial and Shallow Marine Deposits, Gulf of Thailand: Eustatic and Structural Controls, by Hernán M. Reijenstein, Janok P. Bhattacharya, Henry W. Posamentier, and John P. Castagna; #90078 (2008)
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Seismic Geomorphology of Fluvial and Shallow Marine Deposits, Gulf of Thailand: Eustatic and Structural Controls

Hernán M. Reijenstein1, Janok P. Bhattacharya1, Henry W. Posamentier2, and Previous HitJohnNext Hit P. Previous HitCastagnaTop1
1Department of Geosciences, University of Houston, Houston, TX
2Chevron Corporation, Houston, TX

We examined the regional eustatic and local structural controls on the evolution of Late Cenozoic to Holocene shallow marine to fluvial depositional systems using high quality 3D seismic data from the Gulf of Thailand. Changes in plan view morphology of fluvial systems are intimately related to adjustments of the system to local and regional slope variations, which are hypothesized to be controlled by underlying normal faults, as well as eustatic and other allogenic controls.

Plan view images (time and horizon slices) and cross sections from the uppermost 2 seconds of the data set exhibit clearly defined channels and channel belts deposited on the shelf during times of subaerial exposure, and are interpreted to be associated with lowstands of sea level. Single meandering channels are up to 900 meters wide, and form channel belts up to 10 kilometers wide, indicating the presence of continental scale river systems. Incised tributaries and trunk valleys, identified at various depths within the data volume, indicate sustained periods of erosion, which are correlated to maximum Pleistocene lowstand periods. Unincised fluvial systems are likely linked to less extensive drops in sea level when vast areas of the shelf were exposed but the shelf edge was still submerged, forming type 2 sequence boundaries.

The fluvial systems alternate with rare horizons showing positive-relief elongate-shaped morphologies with dimensions of up to 3 km long, 300 m wide, and 5-10 m in height. These are interpreted as shelfal tidal sand ridges and are though to indicate potentially short-lived, but areally extensive transgressions.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas