STUDI KARAKTERISTIK BATUAN DASIT DAERAH SINDANGRATU DAN SEKITARNYA, KABUPATEN LEBAK PROVINSI BANTEN

Abstract

analisis petrografi menunjukkan keterdapatan mineral plagioklas yang melimpah sebagai fenokris, mikrokristalin kuarsa sebagai massa dasar serta mineral biotit dan sanidin dengan tingkat kristalisasi hipokristalin, bentuk kristal subhedral, dan tekstur porfiritik. Pada sampel petrografi juga ditemukan adanya mineral sekunder berupa klorit yang mengindikasikan batuan dasit yang diteliti mulai mengalami altrasi.

Kata Kunci: Dasit, Banten, Karakteristik, Petrografi

ABSTRACT : Research on dacite characteristic has been carried out in the area of Mount Buleud and its surroundings. Geographically, it is located in Sindangratu, Panggarangan District, Lebak Regency, Banten Province. Geologically the study area belongs to the Bayah Dome area and mountains in the central depressive zone on the western part of Java Island. Dacitic rock units in the study area are intrusive rocks that are Middle Miocene-Late Miocene age. The aim of this research is to identify characteristics of dacite in the study area based on optical properties by the thin section. This study was conducted by field observations and petrographic analysis of the thin section of dacite rock. Petrographic analysis shows abundant amount of plagioclase minerals as phenocrysts, microcrystalline quartz as groundmass and biotit and sanidin minerals with the crystallization degree of hypocrystalline, subhedral crystal form, and porphyritic texture. Petrographic samples consists of secondary minerals in the form of chlorite which indicates that the dacite rock under study has slightly altered.

Keyword: Dacite, Banten, Characteristic, Petrography