PROVENANCE STUDY ON THE SANDSTONE OF KUBANG PASU FORMATION, KEDAH

As far as mega researches are concern, no study has been carried out on the provenance of the sandstone in Kubang Pasu Formation in Kedah. Thus, studies on a number of sandstone outcrops from Kubang Pasu Formation in central Kedah, (3 localities nearby Pokok Sena and Pendang) were undertaken to unravel the sandstone parent-rock lithology, source and depositional site distance, climate of source area (weathering) and depositional environment through petrographic, grain size and chemical analyses. In general, petrographic analysis showed that the sandstone in study area are very fine to very coarse grained, very poorly to good sorted, grains shape from angular to sub-rounded with concavo-convex contacts, matrix and grain supported with porosity ranged from 3 to 15%. The sandstones composed of 11% to 77% quartz, 3% to 6% feldspars and rock fragments from 3% to 57%. The sandstones are considered immature to submature rocks with variable types, namely sublitharenite, lithic greywacke and feldspathic greywacke. In summary, the sediments are multi-sourced, varies from volcanic, plutonic igneous, sedimentary to metamorphic rocks. Based on Suttner et al. (1981) QFR ternary diagram, the main deposits were originated from metamorphic humid and arid area. The sediments sources could be originated from older formation such as Jerai Formation in North-western part of Peninsular Malaysia and Jerai Formation in Kedah. The proximity of the source and depositional basin varies from proximal to distal. Linear discriminant function reveals deep water environment, supported by passive margin tectonic deduction (Kroonenberg, 1994). Chemical Index of Alteration (CIA) (Nesbitt & Young, 1982) and Chemical Index of Weathering (CIW) (Harnois, 1988) reflects hot and humid climate for Locality 1, wet and warm climate for Locality 2 in contrast to the change of cold and dry climate to hot and humid climate for Locality 3. Overall, the sediments in Locality 1 and 2 are sourced from recycled sediments whereas sediments in Locality 3 varies with first cycle and recycled sediments, deduced from Index of Compositional Variability (ICV) (Cox et al.,1995)