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Structural Characteristic of Oblique Convergent Strike-Slip Faulting: A Case Study of The Seram Trough, Indonesia

Sapiie, Benyamin; Hadiana, Meli; Kurniawan, Ade

Hydrocarbon exploration at Eastern Indonesia encounters numerous challenges including structural complex area. Oblique convergent strike-slip deformation has notoriously generated area with structural complex geometry and pattern resulted from role of various local parameters that control stress distributions. It will create combination shortening and strike-slip faulting and it has been known for generating complex and asymmetry deformation pattern. The main issue is to distinguish between fold-thrust-belt resulted from pure shear and oblique strike-slip fault system. In the most case, it is difficult to recognize them if only using their deformation pattern. Much field evidence indicates both thrust and strike-slip movements can act in the same fault plane. As a result, hydrocarbon exploration in this belt often encounter numerous uncertainty particularly related to fault interpretation. This paper will describe and demonstrate result of integrated study using analogue sandbox modelling and subsurface structural interpretation using existing seismic data supported by several 2-D/3-D balancing cross-sections for explaining deformation pattern in the Seram Fold-Thrust-Belt, Papua, Indonesia. The main purpose of this paper is to demonstrate the important of analyzing strain pattern distribution within the large deformation zone in order to understand their mechanism.

The Seram fold-thrust-belt is characterized as board deformation zone distributed in NW-SE trend for more than ~400 km long and ~100 km wide. Our recent work indicated the fault pattern changing along strike from west to east as well as the dip of the faults from NE to SW. Balancing cross-section show that this belt experienced large amounts of shortening which some location can reach 50%. The results of integrated study indicated that deformation in the Seram FTB including Seram trough is best explained using oblique convergent strike-slip system. Two of modelling variables clearly affected the sandbox modelling results; these are stratigraphic variation and pre-existing basement fault geometry. Lithologic variation was mainly affected in the total number of faults development. On the other hand, pre-existing basement fault geometry was totally influenced in modelling results.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013