Iskandar Zulkarnain


ABSTRACT Sumatera is always recognized as margin of Eurasia continental plate, where the Indian oceanic plate is considered to be subducted beneath continental materials. The subduction system has produced volcanic or magmatic rocks on Sumatera at least since Cretaceous. Chemical analytical results of volcanic rocks in Bengkulu Province on major, trace and rare earth elements reveal that the volcanic rocks are derived from two different tectonic settings where the western side showing island-arc character and the eastern side represents an active continental margin (ACM). The island-arc group is characterized by lower ratio of (Ce/P)N varying between 1.1 to 2.4 and wider range of (P/Zr)N ratio varying from 1.0 to 1.7, while the ACM group show wider variation with (Ce/P)N ratio more than 3.4 and has narrower range of (P/Zr)N ranging from 0.3 to 0.6. The REE pattern of the island-arc in spider diagram shows steady decreasing in rock/chondrite ratio from La to Lu, while the ACM type is characterized by flat trend from Eu to Lu. The results suggest that it is not the whole Sumatera showing continent character, but it is island-arc in origin from Sumatera Fault Zone to the west and becomes ACM to the east.


Sumatera, Island-Arc origin, Active Continental Margin, Geochemical Data, REE

Full Text:



Barber, A.J., 2000, The origin of the Woyla Terranes in Sumatra and the Late Mesozoic evolution of the Sundaland margin, Journal of Asian Earth Sciences, 18, 713–738

Barber, A.J. & Crow, M.J., 2003, Evaluation of plate tectonic models for the development of Sumatera, Gondwana Research, vol. 20, 1-28

Barrett, T.J. and MacLean, W.H., 1999,Volcanic sequences, lithogeochemistry, and hydrothermal alteration in some bimodal volcanic-associatedmassive sulfide systems In: Volcanic-Associated Massive Sulfide Systems: Processes and Examples in Modern and Ancient Settings (C.T. Barrie and M.D. Hannington, editors), Reviews in Economic Geology, v.8, 101-131

Crow M.J., 2005, Pre-Tertiary volcanic rocks, In: Barber, A.J., Crow, M.J & Milsom, J.S., 2005, Sumatra: Geology, Resources and Tectonic Evolution, The Geological Society, London

Curray, J.R., 1989, The Sunda Arc: a model for oblique plate convergence, Netherlands Journal of Sea Research, vol.24, 131-140

Gafoer, S., Amin, T.C., and Pardede., 1992, Geological map of Indonesia, Bengkulu sheet, Geological Research and Development Centre, Bandung

Hamilton, W., 1979, Tectonics of the Indonesian region, U.S. Geological Survey Prof. Paper 1078.

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, Journal of Petrology, vol.27, 745–750.

Miyashiro, A., 1974, Volcanic rockseries in island-arcs and active continental margins, American Journal of Science, vol.274, 321–355

Pearce, J.A., 1983, The role of sub-continental lithosphere in magma genesis at destructive plate margins. In Hawkesworth, C.J. & Norry, M.J. (eds), Continental basalts and mantle xenoliths, Nantwich: Shiva, 230-249

Tatsumi, Y. and Eggins, S., 1995, Subduction zonemagmatism, Blackwell Science, Frontiers in Earth Sciences, 211pp, ISBN 0-86542-361-X

Wilson, M., 1989, Igneous Petrogenesis; a global tectonic approach, Unwin Hyman, London, 466pp

Zulkarnain, I., 2007, Geochemical character of Hulusimpang Formation volcanic around Kota Agung area and their genetic implication, Jurnal JTM international edition, vol. XIV, No.3, 156-167

Zulkarnain, I., 2011, Geochemical Evidence of Island-arc Origin for Sumatera Island; A New Perspective based on Volcanic Rocks in Lampung Province, Indonesia, Jurnal Geologi Indonesia, vol.6, No.4



  • There are currently no refbacks.

Copyright (c) 2012 Iskandar Zulkarnain

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Copyright of Riset Geologi dan Pertambangan (e-ISSN 2354-6638 p-ISSN 0125-9849). Powered by OJS


Indexed by:



Plagiarism checker: