ACOUSTIC FACIES AROUND THE INTRUSIVE COMPLEX OF SALAHNAMA AND PANDANG ISLANDS, MALACCA STRAIT

Subarsyah , S.Si., MT., Ali Albab, Shaska Ramdhan Zulivandama, Eko Saputro, Arif Ali, Imam Setiadi, Muhammad Zulfikar, Faris Nauval, Riza Rahardiawan

Abstract


Salahnama and Pandang Islands lie on the main range of the granite province; both islands are located in the Sunda Shelf, Malacca Straits. These islands are composed of intrusive rocks from Berhala. The rock’s existence will offer a significant contribution to the distribution of surface sediments in the surroundings. The sea dynamics and the geometry of the Malacca Strait will also have an impact on the seabed. Apart from that, global factors such as sea level changes will lead to transformation of the depositional environment and subsurface geology in the strait. Geological conditions of the seabed surface and subsurface can be understood and interpreted based on the acoustic characteristics and reflector patterns of a seismic section. Then, based on the acoustic character and reflector pattern, an acoustic facies can be defined. Seismic data measurements have been carried out around Salahnama and Pandang Islands in 2024. Based on the results of the seismic section, the acoustic facies in the study area are classified into 6 (six), which include AF I – AF VI. Seabed morphological features in the form of sand dunes were identified in the first acoustic facies (AF I); this feature is formed due to geometric aspects, surface currents, and bottom current's which may or may not be triggered by tidal vortices. Acoustic Facies II (AF II) is characterized by sandwave or ripple marks formed by strong seabed currents. AF III was formed after the Last Glacial Maximum (LGM) ended and the depositional environment returned to a shallow marine environment, characterized by a transparent pattern in the seismic section. The erosional truncation at the upper boundary of AF IV indicates a change in the depositional environment from shallow marine to coastal or terrestrial environments during the Last Glacial Maximum period. AF V is acoustic bedrock, and AF VI is characterized by a chaotic pattern, which is interpreted as granitic intrusive rocks.


Keywords


Berhala; Facies; Acoustic; Salahnama; Pandang

Full Text:

PDF

References


Bennette, J.D., M.C. Bridge, N.R. Cameron, A. Djunuddin, S.A. Ghazali, D.H. Jeffery, W. Kartawa, W.Keats, N.M.S. Rock dan S.J. Thompson, 1981. The Geology of the Langsa Quadrangle, Sumatra, Skala 1:250.000. Pusat Penelitian dan Pengembangan Geologi, Direktorat Jenderal Pertambangan Umum, Departemen Pertambangan dan Energi.

Bird, I. M., Taylor, D., and Hunt, C., 2005. Palaeoenvironments of insular Southeast Asia duringthe Last Glacial Period: a savanna corridor in Sundaland. Quaternary Science Reviews: 2228-2242.

Cobbing, E.J., Mallick, D.I.J., Piteld, P.E.J. & Teoh, I.H., 1986. The granites of the Southeast Asian Tin Belt. Journal of the Geological Society of London, 143, 537–550.

Cobbing E.J., Pitfield, P. E. J., Darbyshire, D. P. F. AND Mallick, D. I. J., 1992, The granites of the South-East Asian tin belt. Overseas Memoir 10 British Geological Survey.

Cobbing, E.J., 2005, Granites, Barber, A.J., Crow, M.J., Milsom, J.S., Sumatra: Geology, Resources and Tectonic Evolution, Geological Society, London.

Cullers, R. L., and Podkovyrop, V. N., 2002. The source and origin of terrigenous sedimentary rocks in the Mesoproterozoic Ui group, southeastern Russia. Precambrian Research 117 157-183 – Elsevier.

Dowdeswell, J.A., Hogan, K.A., Cofaigh, C. O., Fugelli, E.M.G., Evans, J., Noormets, R., 2014. Late Quaternary ice flow in a West Greenland fjord and cross-shelf trough system: submarine landforms from Rink Isbrae to Uummannaq shelf and slope. Quartenary Science Review, 292-309.

Deng, X., Huang, K. and Li, X., 2024. Sedimentary Characteristics and Evolution of the Late Miocene to Quaternary Tributary Channels in the Head of Bounty Channel, New Zealand. Appl. Sci 14 6160.

McCourt, W.J., Crow, M.J., Cobbing, E.J., Amin, T.C., 1996. Mesozoic and. Cenozoic plutonic evolution of SE Asia: Evidence from Sumatra, Indonesia. Geol. Soc.

Metcalfe, I., (2013). Gondwana Dispersion and Asian Accretion: Tectonic and. Paleogeographic Evolution of Eastern Tethys. Australian Journal of Earth.

Mollengraaff, G.A.F., 1921. Modern Deep-Sea Research in the East Indian Archipelago. Geographical Journal 57, 95–121.

Novak, A., Smuc, J., Poglajen, S., and Vrabec, M., 2020. Linking the high-resolution acoustic and sedimentary facies of a transgressed Late Quaternary alluvial plain (Gulf of Trieste, northern Adriatic), 419.

Schulten, I. Micallef, A., Krastel. S., Urlaub, M., Gutescher, M. A., and Kopp, H., 2023. Reconstruction of the 1908 Messina gravity flow (central Mediterranean Sea) from geophysical and sedimentological data, 459.

Susilohadi, Novico, F., Husson, L., Rahardiawan, R., Prabowo, H., Widodo, J., and Sudjono, E. H., 2024. Quaternary deposition and erosion in the northeastern Sunda Strait: An interplay between sea level, tectonics, and magmatic activity. Journal of Asian Earth Sciences X 12.

Van Gorsel, J.T. 2018. Bibliography Of the Geology of Indonesia and Surrounding Areas Edition 7.0. https://vangorselslist.com.




DOI: http://dx.doi.org/10.32693/bomg.40.2.2025.938