Basement Characteristic Western Part of Java, Indonesia ; Case Study in Bayah Area, Banten Province

Abstract

Recent study reveals that in Bayah Complex, 20 km west of Ciletuh Melange Complex, discovered a metamorphic rock that interpreted as the basement of Java. The aim of this research is to know the characteristic of metamorphic in Bayah areas. The result shows that the metamorphic rocks of Bayah Geological Complex are dominated by mica schist group i.e. muscovite schist, muscovite - biotite schist, garnet biotite schist and chlorite schist associated with Pelitic - Psammitic protolith. The amphibolite, epidote amphibolite and actinolite schist found were metamorphosed of mafic rock protolith. All of them have been deformed and altered. Based on mineral assemblage, mica schist group included lower greenschist - epidote amphibolite facies, whereas actinolite schist, epidote amphibolite schist and hornblende schist included greenschist facies, epidote amphibolite facies and amphibolite facies respectively. Based on the data, these metamorphic rocks are associated with orogenic style. The metamorphic rocks exposed to the surface through a complex process since Late Cretaceous. Metamorphic rocks have been deformed, folded and faulted since its formation. Its possible this rock was uplifted to the surface due to intrusion of Cihara Granodiorite.