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ABSTRACT: Insights from satellite gravity into the architecture of Sundaland and the extent of petroleum basins

Hoffman, Nick , La Trobe 3D-GEO, Bundoora, Australia

Regional gravity and topography datasets provide a powerful tool for examining the architecture of basement blocks and rift basins. The datasets reflect Sundaland's assembly from a series of accreted arcs and continental fragments. A pervasive and continuous tectonic fabric extends from Sumatra and Java, through Kalimantan, Malaysia, Thailand and Cambodia. Intervening seas are fundamentally part of the same system and Tertiary rift basins are extensional reactivations of the same accretionary fabric. Present-day analogues include the East China Sea, and the Japan and Marianas arcs.

In an extension of the satellite gravity technique, topography and bathymetry datasets are combined with gravity anomaly data to provide a joint measurement of subsidence versus uplift. In active Tertiary rift basins, present-day bathymetry is a reflection of ongoing subsidence in basin depocentres. Data from the Gulf of Thailand show how the use of satellite gravity alone is misleading and fails to measure sedimentary thickness, whilst adding in the bathymetry yields an accurate search tool for locating depocentres that will form active hydrocarbon kitchens and charge adjacent structural traps.

With appropriate modification, the technique can be used in active Tertiary deltaic systems such as the Gulf of Mexico, the South Atlantic margins, and deltas throughout South-East Asia.

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