Bulletin of the Geological Society of Malaysia, Volume 35, July 1994, pp. 37-46
1Department of Geology & Geophysics, University of New England, Armidale, NSW 2351, Australia
2Department of Geology, University of Malaya, Kuala Lumpur, Malaysia
Abstract: A single 1.25 km thick sequence of the Triassic Semantan Formation has been logged along the western portion of the Mentakab-Temerloh bypass. Bivalves and ammonites indicate a Middle Triassic age. The coarse and fine tuffs and mudstones exposed in the sections represent an overall fining upwards sequence implying a possible waning of volcanic activity or shift of volcanic centres. There is no evidence of isoclinal folding or imbricate thrusts in the section which appears to form part of one limb of a large kilometer-scale broad open fold. The Semantan Formation cannot therefore form part of an accretionary prism but could form part of a forearc or intra-arc basin constructed over an accretionary wedge.