Abstract
DOI:10.17014/ijog.2.2.77-90
The lithofacies association, mainly lithology and depositional sequences of the Brown Shale Unit of Pematang Group was studied based on recent fieldwork at Karbindo Coal Mine, in Kiliran Jao Subbasin,West Sumatra, Indonesia. The lower part of the Brown Shale Unit consists of coal and limestone facies which were deposited in a marginal lacustrine area. The limestone was generated by evaporatic processes characterized by the presence of primary calcite crystals. The upper part of the unit, from bottom to top, is composed of six facies associations, among all: amalgamated massive thick bedded shales, interlaminated shales and siltstones, interbedded grey and red shales, fossiliferous shales, massive thick bedded shales, and interlaminated shale and sandstone facies. Those facies were deposited in a shallow to deep water lacustrine environment, characterized by their lithology compositions, sedimentary structures, and fossil contents. The unit has such as high content of reworked organic matters-bearing shales and mudstones. Turbiditic sedimentary structures, gastropods, and bivalves are common.
References
Aswan, Rizal, Y. and Pradana, A. K. A., 2009. Stratal Architecture of Pematang Group, Central Sumatra Basin, based on Molluscan Taphonomic Study: Case Study in Kiliranjao Area. Majalah Geologi Indonesia, 24 (3), p.141-151.
Cabrera, L. and Saez, A., 1987. Coal deposition in carbonate-rich shallow lacustrine systems: the Calaf and Mequinenza sequences (Oligocene, eastern Ebro Basin, NE Spain). Journal of the Geological Society, London, 144, p.452-461. DOI:10.1144/gsjgs.144.3.0451
Carnell, A., Butterworth, P., Hamid, B., Livsey, A., Barton, J., and Bates, C., 1998. The Brown Shale of Central Sumatra: a detailed geological appraisal of a shallow lacustrine sourcerock. Indonesian Petroleum Association, Proceedings 26th Annual Convention, p.51-69.
Carnell, A., Atkinson, C., and Butterworth, P., 2013. A Field Trip to the Syn-Rift Petroleum System of Central Sumatera. Berita Sedimentology, Indonesian Journal of Sedimentary Geology, 27 (8), p.18-20.
Coster, G.L. de, 1974. The geology of the central and south Sumatra basins. Indonesian Petroleum Association, p.77-110.
Darman, H. and Sidi, F.H., 2000. An Outline of The Geology of Indonesia. Indonesian Association of Geologists, Jakarta, p.254.
De Smet, M.E.M. and Barber, A.J., 2005. Chapter 7: Tertiary Stratigraphy. In: Barber A.J., Crow, M. J., and Nilson, J. S. (eds), Sumatra: Geology, Resources, and Tectonic Evolution, Geological Society, London, Memoirs, 31, p.86-97. DOI: 10.1144/GSL.MEM.2005.031.01.07.
Heidrick, T. L. and Aulia, K., 1993. A Structural and Tectonic Model of the Coastal Plains Block, Central Sumatra Basin, Indonesia. Indonesian Petroleum Association, Proceedings 22nd Annual Convention, 1, p.285-317.
Iqbal, M., Suwarna, N., Syafri, I., and Winantris, 2014. Eo-Oligocene Oil Shales of theTalawi, Lubuktaruk, and Kiliranjao Areas, West Sumatera: Are they potential source rocks?. Indonesian Journal on Geoscience, 1(3), p.135-149. DOI:10.17014/ijog.v1i3.198
Platt, N.H. and Wright, V.P., 1991. Lacustrine carbonates: facies models, facies distributions and hydrocarbon aspects. In: Anado´n, P., Cabrera, L., and Kelts, K.(eds.), Lacustrine Facies Analysis: International Association of Sedimentologists, Special Publication, 13, p.57-74. DOI:10.1002/9781444303919.ch3
Silitonga, P.H. and Kastowo, D. 1995. Geological Map of the Solok Quadrangle, Sumatra (Quadrangle 0815) Scale 1:250,000. Geological Research and Development Centre Bandung, 2nd Edition.
Widayat, A.H., Anggayana, K., Syafrizal, Heriawan, M.N., Hede, A.N.H., and Al Hakim, A.Y., 2013. Organic Matter Characteristics of the Kiliran and Ombilin Oil Shales. Procedia Earth and Planetary Science, 6, p.91-96. DOI:10.1016/j.proeps.2013.01.013