Bulletin of the Geological Society of Malaysia, Volume 36, Dec. 1994, pp. 175-186
1 PETRONAS Research and Scientific Services Sdn. Bhd., Lot 1026 PKNS Industrial Estate, 54200 Hulu Kelang
2PETRONAS Exploration Management Department, Menara Dayabumi, Jalan Sultan Hishamuddin, 50778 Kuala Lumpur
Abstract: Over a hundred well-bore breakout directions in the Malay, Sarawak, Sabah and Sandakan basins show consistent correlation with current and past tectonic stress fields. Breakout directions in the younger layers of the Malay Basin are consistent with shallow-focus earthquake stress trajectories associated with subduction of the Indian Ocean-Australian Plate west of Sumatra. In older layers, breakouts responded to north-south regional compression. In the Sarawak Basin, one set of breakout directions follows the change of tectonic grain in the Rajang Accretionary Prism. Patterns of other sets of breakout directions indicate major tectonic boundaries (West Baram Line and an unknown N-S line projecting outward from Kuala Balingian) and en bloc rotations of certain tectonic domains. Most of the other sets of breakout directions seem associated with the SW segment of the South China Sea spreading ridge. Breakout directional patterns in the Sabah Basin differentiate a SW and a NE domain which experienced relative clockwise rotation of 25°. The Sandakan Basin experienced compression normal to its axis and also east-west regional compression that is currently active.