THE PETROLOGY CHARACTERISTIC OF GRANITOID ROCK BASED ON GEOCHEMICAL ANALYSIS OF BAJAU CAPE COAST AND ITS SURROUNDING, WEST KALIMANTAN
The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30†- 109°1'30†E and 0°4...
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| Format: | Article |
| Language: | English |
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Marine Geological Institute of Indonesia
2017-07-01
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| Series: | Bulletin of the Marine Geology |
| Subjects: | |
| Online Access: | http://ejournal.mgi.esdm.go.id/index.php/bomg/article/view/51 |
| Summary: | The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30†- 109°1'30†E and 0°40'30†- 0°54'30†N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O) > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO) ranges 0.07 to 0.55 (moderate) that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this rock is porfiritic texture, hollocrystalline, granular hypodiomorphic and biotite present as phenocryst, yellowish brown, euhedral, thin and platy. The content of oxides element (Na2O and MgO) tend to decrease, whereas of other oxides elements, namely Al2O3, TiO2, K2O, FeO and CaO increased, parallel with the raising of SiO2. Therefore, the Singkawang Granitoid can be grouped as alkali feldspar granite, syeno-granite and quartz monzonite. |
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| ISSN: | 1410-6175 2527-8843 |