PETROGENESA BATUAN VULKANIK FORMASI CIKOTOK DAERAH CIHARA DAN SEKITARNYA KABUPATEN LEBAK PROVINSI BANTEN
| Main Author: | Alamsyah, Fadhli |
|---|---|
| Format: | bachelorthesis doc-type Bachelors |
| Bahasa: | ind |
| Terbitan: |
, 2020
|
| Online Access: |
http://repository.unpad.ac.id/frontdoor/index/index/docId/38825 |
Daftar Isi:
- ABSTRACT The research was conducted in Cihara District, Lebak Regency, Banten Province. In geology scope this research location well-known as Bayah area (more specific Cikotok Formation). This research discusses characteristics and petrogenesis of volcanic rocks. The objects under study includes of lithology which is texture, structure and the composition of prime mineral and secondary mineral of rocks. The methods used in this research include field, laboratory, and studio method. Laboratory method include petrographic analysis using polarization microscope while studio method uses data/map/image processing software such as MapInfo Photoshop, and CorelDraw. The andesitic lava rock distribution is on the north of research area which stratigraphicaly positioned under the Granodiorit Cihara Formation and above of Bayah Formation. There are 5 andesitic rocks and 3 tuffs that have been successfully mapped. Andesitic lava rocks are have similar characteristics that is trachytic texture, amygdaloidal structure and embayment structure. Tuff has some composition which are vulcanic glass and tuf vitric as rock fragments so it will be classified as tuff litics. There is xenolith which characteristics similar to the source rock so it is possible there are at least twice of the volcanic period. The first period is the process of formation of xenoliths and then followed by andesitic lava rocks with the same composition. Alteration exists because of weak zone as a result of vulcanical activity. Secondary mineral which exist are chlorite, epidote, sericite, quartz and clay minerals. Based on secondary mineral, rocks in the research area are classified as alteration zone phyllic-propylitic. Keywords: Bayah, Petrogenesis, andecitic lava, tuff litic, alteration.