Bulletin of the Geological Society of Malaysia, Volume 42, Dec. 1998, pp. 187 – 196
Department of Geology, University Malaya, 50603 Kuala Lumpur
Abstract: Based on a preliminary sedimentological and deformational study, the Tertiary Boulder Beds of Batu Arang can be divided into two distinct sequences – the Red and the Gray Conglomeratic units, separated by an angular unconformity. The Red Conglomeratic Unit was deposited sub-areally, whilst the Gray Unit was deposited in a reducing, subaqueous environment.
Numerous evidences for the interplay between tectonism and sedimentation are found within the Boulder Beds. These includes:
1. the immaturity of the sediments, compositionally and texturally;
2. cyclicity of the fining-upward sequences;
3. the occurrence of the intrabasinal angular unconformity between the Red and the Gray Units;
4. the presence of syn-depositional structures.
These evidences suggest that the Boulder beds were deposited in a fault-controlled basin. The presence of post-depositional strike-slip faults suggest that tectonism out-lasted sedimentation and together with the proximity of the basin to the Kuala Lumpur Fault zone, may suggest that the basin may have developed along a strike-slip fault.