Bulletin of the Geological Society of Malaysia, Volume 42, Dec. 1998, pp. 179 – 186
School of Physics, Universiti Sains Malaysia, 11800 USM Penang
Abstract: The Bukit Arang Tertiary Basin extends from the Perlis-Thailand border at Bukit Arang-Bukit Tinggi southwards to the Chuping area of eastern Perlis. It is part of the larger Sadao Basin located across the border in Thailand. Another southern extension of this main basin is found in the vicinity of Bukit Kayu Hitam, north of Changlun, just a few kilometres to the east across the interstate boundary in Kedah. Based on sparse geological evidence, the original postulated areal extent of the basin within Perlis was approximately 26 square kilometres with a minimum thickness of about 200 m. Recent gravity data indicate that it is at least twice as large in area and up to 800 m thick.
The sediments consist of loose and partially consolidated gravels, sands, silts and clays of lacustrine and fluvio-deltaic origin of Late Tertiary age. They are underlain by shales, mudstones and siltstones of the Kubang Pasu Formation of Carboniferous age. Geophysical evidence suggests that this basement is uneven, with a ridge-like feature in a north-south orientation. The basement appears to be faulted as well with WNW-ESE and approximately N-S strikes.
Stratigraphically these Tertiary Beds can be correlated with the very similar strata of the Batu Arang Tertiary Basin of Late Oligocene to Late Miocene age in Selangor and with other Tertiary basins of similar lithology elsewhere in the peninsula.
The Bukit Arang Tertiary Beds contain several seams of low quality coal of not much economic significance. Good quality clay of possible commercial value is also present. There are traces of oil in the shales and small amounts of cassiterite have been reported from the sands. However, the main economic potential of these Tertiary Beds lies in their aquifers which are currently being exploited by the sugarcane plantations covering a large part of the area.