SEDIMENTOLOGY AND STRATIGRAPHY (BIOSTRATIGRAPHY) OF THE KAYAN SANDSTONE FORMATION, LUNDU AREA, SARAWAK

This project presents the results of sedimentological studies of the Kayan Sandstone Formation that exposed along the Bau-Lundu road in Sarawak. Samples collected were analyzed under thin section and sieving method is used to study about grain size distribution. Samples also has been sent to Biostratex Sdn. Bhd for palynology analysis to study about the pollen origin and their depositional environment. This work presents the detailed facies analysis of Kayan Sandstone Formation. Five types of sedimentary facies were recognized in the Kayan Formation along Bau-Lundu road Sedimentary facies identified are i) Small to large scale trough cross-bedded facies, ii) Bioturbated sandstone, iii) Sand alternating clay bedded facies and iv) Massive sandstone v) Massive Mudstone. These rocks are interpreted as typical fluvial deltaic depositional environment based on the fining upward trend in sedimentary log. Based on thin section and sieving analysis conducted, the grain of Kayan sandstone if fine to medium grain size, moderately sorted and has moderate sphericity. Kayan Sandstone Formation has been interpreted to be deposited in Eocene age based on palynology analysis. This is also supported by the presence of Florschuetzia trilobata which are the local palynomorphs marker for the Eocene interval.