Bulletin of the Geological Society of Malaysia, Volume 38, Dec. 1995, pp. 109 – 126
Petronas Research & Scientific Services Sdn. Bhd., Lot 1026, PKNS Industrial Estate, Ulu Kelang, 54200 Kuala Lumpur
Abstract: The Tertiary basement of the Strait of Malacca (Malaysian waters) slopes gently towards southwest. Northerly trending grabens have been mapped within the basement at discrete locations. These grabens, from south to north, are Kukup Graben, Johor Graben, Port Klang Graben, Angsa Graben, Sabak Graben, Southern Graben, Central Graben, Eastern Graben, East Penang Graben, West Penang Graben, North Penang Graben, MSS-XA Graben, and Northern Graben. The maximum depths of these grabens range from 900 metres to 4,000 metres. The Tertiary basement topography of some grabens has been altered by structural modification during ?Late Miocene. These grabens can be grouped into (1) Bengkalis Trough related grabens, (2) Pematang-Balam Trough related grabens, (3) Asahan Arch-Kepulauan Aruah Nose related grabens and (4) Tamiang-Yang Besar High related grabens. These graben groupings are situated between regional highs. These graben groupings are also elongated in northerly direction and may represent regional fracture zones. The zones are initiated during Lower Oligocene by right lateral shearing in the NW-SE direction.