Abstract: Structural Styles in the Balingian Province, Offshore Sarawak

Peter Swinburn

The Balingian province has been subjected to multiphase convergent and divergent wrenching in Tertiary times. The province is bounded to the north by the more stable central Luconia province, while to the south lies the Anau-Nyalau fault zone bordering the onshore Tatau Horst. To the west and east lie the west Balingian line and west Baram lines, respectively, which are major northwest-southeast-trending lineations, similar to the Lupar line, and may represent an old transform fault.

Deformation is related to movement along major bounding transform faults and the opening of the South China Sea. The hardness of the pre-Tertiary basement observed on seismic data strongly influences the style of deformation of the overburden. The Balingian province can be divided into three subprovinces, each with different structural trends and timing. (1) The east Balingian subprovince is an area of strong, late Miocene to Pliocene wrench-related deformation with structural axes oriented northeast-southwest. Individual structures are typically large, high amplitude folds, bounded by reverse faults, which converge at depth and can be related to oblique strike-slip movements. (2) The southwest Balingian subprovince is an area of Oligocene to early Miocene wrench-related deformation o varying intensity. Structural axes trend northwest-southeast. The dominant fault trend is northeast-southwest and is characterized by basement faulting in the west and growth faults on the flanks of the Balingian basin to the southeast, (3) The northwest Balingian subprovince was subjected to several phases of strong deformation from Oligocene to Pliocene and is characterized by en echelon northwest-southeast-trending folds with complex fault patterns.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994