GENERAL GEOLOGY OF PULAU LANGGUN, LANGKAWI, KEDAH AND A PRELIMINARY STUDY ON THE MORPHOLOGY OF GRAPTOLITES

The geology of northeastern Pulau Langgun was found to consist of shale interbedded with carbonaceous mudstone, dark-colored limestone, mudstone, and siltstone with sandstone lenses, which is in respect with its geologic age, being from Ordovician to Carboniferous in age. This is in accordance to the sequence developed in previous study, Tanjong Dendang Formation, Mempelam Limestone, Timah Tasoh Formation, and Langgun Red Beds (Basal Singa Formation). Structurally, the outcrops of Pulau Langgun are not exempted from the tectonic forces exerted on the Langkawi islands, which is trending ENE-WSW. Among the structures observed include conjugate joints, orthogonal joints, a normal fault and folds. Known for its abundance of fossils, particularly graptolites, samples were taken from the Tanjong Dendang Formation to be observed under the binocular microscope. Sketches of the fossils indicate that the graptolites discovered are of Glyptograptus sp., Dimorphograptus sp., & Pristiograptus sp. which originate from the lower Silurian. The Total Carbon Analysis shows that the organic carbon content of the outcrops here are of poor to very good, which may suggest the rock potential as source rock. This will enhance the source rock studies of Paleozoic rocks in Malaysia in future oil and gas explorations of the area.