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. This research aims 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 the 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 the intrusion of Cihara Granodiorite.

The Transitional Gabbroic Rocks in Bayah Geological Complex, Western part of Java, Indonesia, Inferred from XRF, ICP-MS, and Microprobe Analysis

“…Recently, around 20 km northwest of CMC, western part of java, another gabbro has been found in Bayah Geological Complex (BGC) (Patonah and Permana 2018). The gabbro in BGC found boulders together with metapelitic rocks, it has not been found ultramafic yet.…”

Petrological Characteristic and Whole Rock Geochemistry of Metamorphic Rocks in Melangè Complex of Ciletuh Area, West Java, Indonesia

“…Along with Luk Ulo and Meratus, Ciletuh was considered formed in the southernmost margin of Cretaceous Sundaland subduction system as tectonic mélanges based on the observation of the exposed rocks and their structural configuration [1]. This complex is formed by a complicated geological process of subduction, abduction and a combination of collision between plates and back arc thrust complex [2]. Jampang and Balekambang Geological Map Sheet classified these rocks complex into three units of Pre-Tertiary rock, namely Pasir Luhur, Gunung Beas, and Citirem Formation.…”

“…Group of metamorphic rocks in the melange complex of Ciletuh first mentioned by [2], concerning the status of the complex melange. Greenish serpentinite can be recognized in Tegal Pamidangan, Mount Beas, Citisuk River, and Tegal Cikepuh River Belt in the central part of the region Ciletuh.…”