GEOLOGICAL CONTROL FOR THE OCCURRENCE OF TAMPOMAS VOLCANO THERMAL MANIFESTATION

• Main Author: YESY SIANIPAR, JUNI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63315
• Institution: Institut Teknologi Bandung

The research area is located at Tampomas Volcano, Sumedang Regency, West Java. The geological mapping of Tampomas Volcano and its surrounding area has been carried out in the previous study. However the control of geological condition for the occurrence of thermal manifestation has never been discussed before. Surface manifestations are controlled by geological process associated with primary permeability (contact of rock units) and secondary permeability (geological structure). The purpose of this research is to find out the geological control for the occurrence of surface manifestation and the objective of this research is to determine the boundary of rocks units, fault zone, control of the appearance of manifestations and interpret subsurface geological condition. The methodology used in this research consist of remote sensing analysis, geological mapping, laboratory analysis and measurement of Rn222 in the field. Remote sensing is used as guidance to generate the boundary of rocks units and lineament associated with geological structure. The result of remote sensing analysis was built in Preliminary Volcanostratigraphy Map and Geological Lineament Map. Geological mapping was conducted both for lithology contact identification and structure validation by the fact that both of them has potential to control permeability. Regional geology, profile of electrical resistivity and lithological mapped result were combined to generate the valid geological map. Evidence of surface geological structure in the field, gravity anomaly lineament, Hg and CO2 distribution map were combined to generate the valid geological structure. Furthermore, the valid geological map and valid geological structure was used to generate the Boundary of Rocks Unit Map and Geological Structure Map. Surface manifestation controlled by boundary of rock unit lies in the buffer of boundary rock unit area with low Rn222 concentration in soil gas and low CH4 concentration in dissolved gas of manifestation. Surface manifestation controlled by geological structure lies in the buffer of geological structure (fault) with high Rn222 concentration in soil gas and high CH4 concentration in dissolved gas of manifestation. Result from this study shows that Tampomas surface manifestations are controlled by geological structure and rock unit boundaries. All thermal manifestations including 1 hot springs and 8 warm springs, 5 cold springs lie in geological structure buffer area and 3 cold spring lie in the boundary of rock unit buffer area.