Analysis of gravity anomaly decomposition and depth to basement, case study: Cenozoic Bogor Basin, Indonesia.

Abstract

The Cenozoic Bogor Basin situated on the SE edge part of Sunda shelf is presumed to have hydrocarbon potential on its turbidite deep-water play. The deep subsurface geometry of this basin may play an important role, yet unexplored, to the hydrocarbon exploration. The gravity method is advantageous to illuminate the subsurface structure on the arbitrary depth and various sources. Eight-hundred-thirty-eight points of ground-based gravity survey were collected on roughly one kilometer spacing in the North of Bandung to Pamanukan region covering the Cenozoic Bogor Basin on the Subang-Purwakarta segment to generate complete Bouguer anomaly (CBA) map. This study examines the two robust methods of gravity anomaly decomposition (i.e., polynomial trend surface and upward continuation) by using multiple parameters to match the geological background. Radially averaged power spectrum was used to estimate the depth of anomalous source corresponds to the top of basement layer and resulting 4 km basement depth in North West Java basin and below 1 km on Tangkuban Parahu volcanic zone. The resulting estimated depth of Cenozoic Bogor Basin was evaluated by the matched a priori published data on those two areas and revealed the depth of depocenter (deepest sediment) on the Cenozoic Bogor Basin is up to 9 km, quite a deeper extent than previously assumed.