Geological Notes: Warta Geologi, Vol. 45, No. 1, January-March 2019, pp. 6-12





Description

Sedimentology facies of the Tatau Formation, Tatau-Bintulu Road transact, Sarawak, Malaysia

Ngui Jia Qi1,*, Abdul Hadi Abd Rahman1, Azfar Mohamed2
1Department of Geosciences
2Department of Petroleum Engineering
Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia
*Corresponding author email address: jiaqi.ngui@gmail.com


Abstract: Sarawak is divided into four zones, namely the West Borneo Basement, Kuching Zone, Sibu Zone and Miri Zone. The Sarawak Basin in the state covers both onshore and offshore areas, divided into several geological provinces which are of Palaeogene to recent age. On the shelf of the basin, sedimentary succession exceeds 12 km thick (Tan & Lamy, 1990). The study area which is located between Tatau and Bintulu, consists of sediments which are Neogene in age. Sedimentology and stratigraphy study was carried out on the Neogene sedimentary succession at the study area, which stretches around 10 km to 15 km northeast of Tatau town and southwest of Bintulu town. A total of four outcrops were studied. The results are based on field survey of the outcrops across the study area and laboratory analysis of the collected sedimentary samples from the field. The facies analysis results in the identification of seven facies which can be are sand-dominated facies and mixed sand and mud-dominated facies. The sedimentary successions were deposited in an estuarine-inner shelf region.


Keywords: Sarawak basin, early Neogene, Miri Zone, Tatau Formation


Abstrak: Sarawak dibahagikan kepada empat zon iaitu West Borneo Basement, Zon Kuching, Zon Sibu dan Zon Miri. Lembangan Sarawak dibahagikan kepada beberapa wilayah geologi yang berumur Paleogen sampai sekarang, meliputi kedua-dua kawasan di dalam dan luar pesisir. Di pelantar lembangan, ketebalan sedimen melebihi 12 km (Tan & Lamy, 1990). Kawasan kajian yang terletak di antara Tatau dan Bintulu terdiri daripada sedimen yang berusia Neogene. Kajian sedimentologi dan stratigrafi telah dijalankan di kawasan kajian yang terbentang di sekitar 10 km hingga 15 km timur laut dari bandar Tatau dan barat daya dari bandar Bintulu. Sebanyak empat singkapan telah dikaji. Keputusan adalah berdasarkan kajian di singkapan dalam kawasan kajian dan analisis di makmal menggunakan sampel yang dikumpul. Melalui analisis fasies, tujuh jenis fasies telah dikenal pasti di mana fasies tersebut boleh dikategorikan sebagai fasies yang didominasi oleh pasir dan fasies yang didominasi oleh pasir dan lumpur. Sedimen telah dienapkan di kawasan muara-dalaman.


Kata kunci: Lembangan Sarawak, Neogene awal, Zon Miri, Formasi Tatau

DOI : https://doi.org/10.7186/wg451201902