Indonesian Journal on Geoscience
Vol 2, No 3 (2015)

Metamorphic Evolution of Garnet-bearing Epidote-Barroisite Schist from the Meratus Complex in South Kalimantan, Indonesia

Setiawan, Nugroho Imam (Geological Engineering Dept., Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta, Indonesia)
Osanai, Yasuhito (Division of Earth Sciences, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka)
Nakano, Nobuhiko (Division of Earth Sciences, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka)
Adachi, Tatsuro (Division of Earth Sciences, Faculty of Social and Cultural Studies, Kyushu University, Fukuoka)
Asy’ari, Amril (Mining Department, Banjarmasin State Polytechnic, Banjarmasin)



Article Info

Publish Date
30 Sep 2015

Abstract

DOI:10.17014/ijog.2.3.139-156This paper presents metamorphic evolution of metamorphic rocks from the Meratus Complex in South Kalimantan, Indonesia. Eight varieties of metamorphic rocks samples from this location, which are garnet-bearing epidote-barroisite schist, epidote-barroisite schist, glaucophane-quartz schist, garnet-muscovite schist, actinolite-talc schist, epidote schist, muscovite schist, and serpentinite, were investigated in detail its petrological and mineralogical characteristics by using polarization microscope and electron probe micro analyzer (EPMA). Furthermore, the pressure-temperature path of garnet-bearing epidote-barroisite schist was estimated by using mineral parageneses, reaction textures, and mineral chemistries to assess the metamorphic history. The primary stage of this rock might be represented by the assemblage of glaucophane + epidote + titanite ± paragonite. The assemblage yields 1.7 - 1.0 GPa in assumed temperature of 300 - 550 °C, which is interpreted as maximum pressure limit of prograde stage. The peak P-T condition estimated on the basis of the equilibrium of garnet rim, barroisite, phengite, epidote, and quartz, yields 547 - 690 °C and 1.1 - 1.5 GPa on the albite epidote amphibolite-facies that correspond to the depth of 38 - 50 km. The retrograde stage was presented by changing mineral compositions of amphiboles from the Si-rich barroisite to the actinolite, which lies near 0.5 GPa at 350 °C. It could be concluded that metamorphic rocks from the Meratus Complex experienced low-temperature and high-pressure conditions (blueschist-facies) prior to the peak metamorphism of the epidote amphibolite-facies. The subduction environments in Meratus Complex during Cretaceous should be responsible for this metamorphic condition.

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Journal Info

Abbrev

IJOG

Publisher

Subject

Earth & Planetary Sciences

Description

The spirit to improve the journal to be more credible is increasing, and in 2012 it invited earth scientists in East and Southeast Asia as well as some western countries to join the journal for the editor positions in the Indonesia Journal of Geology. This is also to realize our present goal to ...