Sedimentology and potential coal resources in Susui Block, Pinangah, Sabah

The Susui Block in Pinangah area located northwest of the greater Maliau Basin in central Sabah is underlain by the coal-bearing Tanjong Formation of Early-Middle Miocene age. This study was conducted to determine the sedimentary characteristic of the coal bearing sequence, the quality of the coal and the coal resources in the area. The methods employed included geological field investigation and laboratory analyses. The field survey comprises mapping of coal outcrops and studying core samples recovered from portable Winkie Drill machine. Laboratory analyses comprises mainly of proximate and ultimate analyses, as well as organic geochemistry analyses (pyrolisis) and petrographic analysis for maceral identification. The coal bearing sequence comprised of four main fades namely a) Coal Fades, b) Carbonaceous Mudstone Facies, c) Mudstone Facies and d) Heterolithic Siltstone Facies. The sedimentary structures found within the Mudstone Facies and Heterolitic Siltstone Facies such as parallel lamination, cross lamination and bimodal lamination indicate a protected mid-flat tidal environment of deposition whereas the Coal Facies and Carbonaceous Facies were deposited in a lagoon environment. The sulphur content of the coal is more than 0.5 °/o indicating sea water intrusion. The atomic ratio for Hydrogen and Oxygen plotted onto the Van Krevelen's diagram showed that the coal is made up of immature to mature organic matters deposited in a swamp or lagoon environments. Petrographic analysis conducted for maceral identification categorized the coal as humic of Clarite Microlithotype (vitrinite + liptinite> 95 %) derived from humification process of terrestrial plant with minor association of planktonic algae probably from the aquatic environment. Four coal seams were mapped in the area aligned in a semi-circular basin with dipping indinations ranging from 12° to vertic.al towards the centre of the area. The coal resource is estimated at 44.6 million tonnes of high volatile bituminous coal (hvbc), a premium quality for electricity generation. The study shows a good potential for coal mining development and the coal mining life could extend for at least 30 years operation, based on projection of 90,000 metric tonnes of monthly production