PETROLOGI DAN GEOKIMIA BATUAN GUNUNG API TERSIER JELAI DI DAERAH MALINAU, KALIMANTAN TIMUR: Implikasi tektoniknya

Authors

  • Baharuddin Baharuddin Pusat Survei Geologi

DOI:

https://doi.org/10.33332/jgsm.geologi.v21i4.147

Abstract

Geology of Malinau region in east Kalimantan is very little known because of its difficulties in accessibility. The aim of this study is to present petrology and geochemical data of the Tertiary Jelai Volcanic rocks and its tectonic implications. Nine samples have been analysed using XRF (major elements) and ICP-MS (trace and rare earth elements) methods and three samples were examined for absolute age dating using a K-Ar method. The Tertiary Jelai volcanic rocks in Malinau area are dykes and lavas having basalt-andesite-dacite in composition . Based on petrology and geochemistry data, the Jelai Volcanic rocks are medium medium calc-alkaline to tholeiitic series. Depletion of Nb and Ti indicates an island arc affinity. Absolute age dating using potassium-argon method for three rock samples yielded ages that vary from 16.13 ± 2.67 to 14.72 ± 0.90 m.a. or Neogene-Miocene-Burdigalian to Neogene-Miocene-Langhian. It can be concluded that the existence of Jelai volcanic rock is strongly related to subduction of the Palawan Oceanic Plate beneath East Kalimantan during the Middle Miocene soon after subduction of the South Chine Sea Plate ceased which is formed the Sintang Intrusives during the Oligo-Miocene time.


Keywords: Tertiary Jelai volcanic rocks, petrology, geochemistry and tectonic

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References

Abidin, H.Z., Pieters, P.E., and Sudana, D., 1993. Geological map of the Long Pahangai Sheet, Kalimantan 1:250.000 scale. Geol. Res. Dev. Centre, Bandung.

Baharuddin., Pieters, P.E., Sudana, D., and Mangga,S. A., 1993. Geological map of the Long Nawan Sheet, Kalimantan 1:250.000 scale. Geol. Res. Dev. Centre, Bandung.

Carlile,J.C and Mitchell, A.H.G., 1994. Magmatic arcs and gold - copper mineralisation in Indonesia. In: van Leeuwen, T.M., Hadenquist, J.W., James, L.P. and Dow, J.A.S. (Eds.), Mineral Deposits of Indonesia - Discoveries of the past 25 years. Journal of Geochemical Exploration, Special issue, 50:91-142.

Daly, M.C., Hooper, B.G.D, and Smith, D.G., 1987. Tertiary plate tectonics and basin evolution in Indonesia. Proceeding Indonesian Petroleum Association, 6th Annual Convention, Jakarta.

Hamilton, W., 1979. Tectonics of the Indonesian region. United States Geological Survey, Professional Paper, 1078.

Hartono,U., 1994. The Petrology and Geochemistry of the Wilis Volcanoes east Java, Indonesia. Unpublished Ph.D. Thesis, University of Tasmania.

Heryanto, R., Supriatna, S dan Abidin, H. Z., 1995. Geologi Lembar Malinau, Kalimantan sekala 1:250.000. Pusat Penelitian dan Pengembangan Geologi, Bandung.

Hutchison, C.S., 1988, Stratigraphic-Tectonic Model for Eastern Borneo, Geol. Soc. Malaysia, Bulletin 22: 135 – 151.

Hutchison, C.S., 1996. 'The Rajang accretionary prism' and 'Lupar Line' problem of Borneo. In Hall, R & Blundell, D. (Eds.), Tectonic Evolution of Southeast Asia. J. Geol. Soc. Special Publication : 106, 247-261.

Le Bas, M.J., Le Maitre, R.W., Streckeisen,A. and Zanettin,B., 1986. A chemical classification of volcanic rocks based on the total alkali-silica diagram. J. Petrology 27 : 745-750.

McDonough W. F. & Sun S-s., 1995. “The Composition of the Earthâ€, Chemical Geology 120: 223-253.

Miyashiro, A., 1974. Volcanic rocks series in island arc and active continental margin. American J. Sci.274: 321-355.

Peccerillo, A. and Taylor, S.R., 1976. Rare Earth elements in East Carpathian volcanic rocks. Earth Planet. Sci. Lett. 32: 121-126.

Setiadi,I., 2009. Delineasi Cekungan Sedimen Daerah Kalimantan Berdasarkan Anomali Gayaberat. Thesis Magister Teknik Geofisika Insitut Teknologi Bandung (Tidak diterbitkan).

Soeria- Atmadja, R., Noeradi, D. & Priadi, B., 1999. Cenozoic magmatism in Kalimantan and its related geodynamic evolution. J. Asian Earth Sci. 17: 25-45.

Sun,S-s.,& McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle compositions and processes. In: Saunders, A.D. and Norry, M.J. (Eds.), Magmatism in the Ocean Basins. The Geological Society, London, Spec. Publ. 42: 313-345.

Thompson, R.N., 1982. Magmatism of the British Tertiary Volcanic Province. Scott.J.Geol.18: 49-107.

William, P.R., & Harahap,B.H., 1987. Preliminary Geochemical and age date from post subduction intrusive rocks, Northwest Borneo. Aust.J. Earth Sci. 34, 405-415.

Wilson,M., 1989. Igneous Petrogenesis. A Global Tectonic Approach. Harper Collin Academic: 466pp.

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Published

2011-08-10