ABSTRACT: Synthetic Aperture Radar Utilized for Regional Geologic Interpretation of the Tectonically Complex, Greater Sarawak Basin

POSEHN, GARY A., and JAMES A. GENEREUX, Intera Information Technologies (Canada) Limited, Calgary, Alberta, Canada, and RICKY M. MANTARING, Idemitsu Oil Exploration (East Malaysia) Co. Ltd., Kuala Lumpur, Msia

Synthetic aperture radar (SAR) data were used to decipher the basin architecture within the Baram Delta area of the Greater Sarawak basin. High-resolution SAR data acquired over northern Sarawak, East Malaysia, allowed a cost-effective reconnaissance of tectonism and its effect on surficial structural elements and distribution of lithostratigraphic terrain units. SAR is an excellent remote sensing tool for structural interpretations, particularly in the dense jungle forest terrain of tropical latitudes. Since SAR is an active microwave sensor, it can penetrate cloud cover and tropical haze. Although X-band SAR does not penetrate the tropical forest canopy, the latter may be considered as a heterogeneous blanket of mixed vegetation up to 30 m high. As the vegetative cover parallels the topography, the underlying geology is interpreted using geomorphic principles. In addition, SAR's side-looking geometry highlights subtle but significant topographic features that contribute to the overall interpretation.

The identification of major northwest to north-northwest-trending transform faults are interpreted from SAR imagery to impart strong tectonic foliation and to warp major fold axes. These transform faults border major tectonostratigraphic provinces within the Greater Sarawak basin, both onshore and offshore, as well as postulated southerly extensions of the major sinistral Red River Fault zone from mainland Asia. Transform faults also act as loci for volcanic activity, subvolcanic and igneous intrusions, shale diapirs, mud volcanoes, and hydrocarbon seepages. The depositional facies edge of the Middle Miocene Setap Shale Formation is controlled by the transform fault Belait Line with deeper marine facies to the northeast. SAR is an effective remote sensing tool for interpretation of th complex evolution of a Tertiary sedimentary basin margin under difficult exploration conditions.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)