GENERAL GEOLOGY OF NORTH FACE OF GUNUNG SEMANGGOL FORMATION TRANSECT BETWEEN KG. BALEK BUKIT TO KG. BAHARU, SIMPANG AMPAT, SEMANGGOL

The Semanggol Formation is a group of sediments that exposed on the Semanggol range in North of Perak. Introduced by Alexander (1959), it was then being grouped by Burton (1973) into three informal group, the chert, rhythmite and the conglomerate member. Formed during the closing of the Paleotethys Ocean and the collision of Sibumasu plate and the Indochina plate, the observation of Pseudoalbaillella sp. and Permian radiolarians extend the age of the sediment from Early Permian to Late Triassic. The sediments formed in deep marine depositional environment. Metcalfe (2000) however recognized that the Semanggol Formation is not simple layer cake formation but rather a sedimentary complex and need reassessment. Thus, this project is intended to cover the unsolved mistery of Semanggol Formation on the North of Perak. The result from the fieldwork conducted shows a great findings, there was a diatreme on the foot of the Gunung Semanggol. It has been developed as quarry but now abandoned, another finding is the presence of sandstone interbedded with siltston overlain by the conglomerate on an unconformity. Some samples are taken for laboratory analysis and based on the studies; two of the samples from the quarry are volcanic breccia while three others are granite, the sandstone raft presence is proofed. The quartz vein observed proved that the quarry is diatreme. Fossil found from siltstone provide good evidence that the siltstone and sandstone interbed are belong to the rhythmite member. The diatreme presence indicate that granite beneath the clastic sediments helps in providing tectonic force that give shape to the present of Gunung Semanggol.