Erzam S. Hasan
Department of Geophysical Engineering, Halu Oleo University, Kendari, Indonesia

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Characteristics of Ultramafic Igneous Rock Ofiolite Complex in Asera District, North Konawe Regency Southeast Sulawesi Province, Indonesia Hasria; Erzam S. Hasan; Deniyatno; L M Iradat Salihin; Asdiwan
Journal of Geoscience, Engineering, Environment, and Technology Vol. 5 No. 3 (2020): JGEET Vol 05 No 03 : September (2020)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2020.5.3.4113

Abstract

The research area is located in Asera District, North Konawe Regency, Southeast Sulawesi Province which has ultramafic rock lithology. The purpose of this study is to determine the characteristics of ultramafic igneous rocks using petrographic and geochemical analysis. Petrographic analysis aims to determine the types and abundance of minerals present so that rock types can be determined based on the classification of Travis (1955) and Streckeisen (1976). The geochemical analysis aims to determine the oxide/major element so that it can determine the type of magma based on the AFM classification according to Irvine and Baragar (1971) and the origin of the magma / original rock formation environment based on Pearce (1977). Petrographic analysis results showed that ultramafic rocks in the study area consisted of 2 types of rocks namely peridotite consisting of wherlit and lherzoite and serpentinite. The results of geochemical analysis indicate that the type of magma in the study area is thoellitic series and the origin of the magma/rock formation environment comes from the expansion of the oceanic floor or mid oceanig ridge (MOR) which is ultramafic.
Serpentinization Study On Ultramafic Rock at Morombo Area, Lasolo Islands District, North Konawe Regency, Southeast Sulawesi, Indonesia Hasria; Febiyanti; Masri; Ali Okto; Erzam S. Hasan; La Hamimu; Sawaludin; La Ode Muhammad Iradat Salihin; Wahab
Journal of Geoscience, Engineering, Environment, and Technology Vol. 7 No. 1 (2022): JGEET Vol 07 No 01 : March (2022)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2022.7.1.6643

Abstract

The research is in Morombo area, North Konawe Regency, Southeast Sulawesi. The purpose of this study was to determine the characteristics of serpentinized ultramafic rock and serpentine paragenesis. Research was conducted using field observations and laboratory analysis consisting of petrographic and geochemical analysis in the form of X-Ray Fluorosence (XRF). Petrographic analysis was carried out to identify the mineral content and textures in the rock and to determine the percentage of serpentine mineral presence. Both of these rocks are petrographically dominated by primary minerals olivine and clinopyroxine and secondary minerals namely lizardite, chrysotile, antiorite and opaque minerals. The XRF analysis was to determine the elements of Ni, Fe, Co, MgO, SiO2, CaO, Al2O3 and P in ultramafic rocks. The results of petrographic analysis show that serpentinized ultramafic rocks in the study area consist of serpentinized dunite and serpentinized peridotite. The formation of clay minerals in rocks does not occur because of the low serpentinization process in the rock. The results of XRF analysis showed that all samples in the bedrock showed Ni content above 0.2%. This is caused by the enrichment of Ni which is interpreted as a result of the serpentinization process along with the formation of lizardite in the rock. The serpentinization sub-processes in the study area comprised by hydration, serpentine recrystallization, and deserpentinization. Serpentine paragenesis is formed from the mid-oceanic ridge ocean floor, the orogenic phase to weathering. Substitution of Mg by Ni in ultramafic rocks will produce Ni-Serpentin. It is estimated that in the research area lizardite and chrysotile lizardite and chrysotile are the causes of Ni enrichment in bedrocks. The serpentinization characteristics of ultramafic rocks in the study area show a low to moderate level of serpentinization.