HYDROGEOCHEMISTRY AND STABLE ISOTOPE ANALYSIS OF SPRINGS ALONG FAULT: CASE STUDY THE LEMBANG FAULT

• Main Author: (NIM: 22716004), Musti’atin
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29410
• Institution: Institut Teknologi Bandung

<p align="justify">Fault can function as a barrier or conduit to fluid flow either laterally or vertically. The fluid that flows vertically comes from deep subsurface. Fluids derived from subsurface usually have different characteristics with fluid in shallow depth or surface. Lembang fault is a normal fault with 22 km long from Mount Palasari in the east to Cisarua in the west with east-west orientation. Hydrogeochemical studies of 60 spring samples including analysis of the major ion, stable isotopes &#948;13C from dissolved carbon dioxide, &#948;18O and &#948;2H in water, and analysis of precipitate using the XRD method was performed to determine the Lembang Fault character against fluid flow from deep subsurface. Elaboration of the results of major ion analysis, stable isotope &#948;13C, &#948;18O and &#948;2H of springs along the Lembang Fault indicate that the source of the spring are limestones and marl. Major ion analysis also showed salting process and characteristics of water-rock interactions which the main process is dissolution of carbonate rocks. Limestone and marl were not found at the research location, but the regional stratigraphic cross section of West Java showed the prescence of both rocks at the bottom of the Lembang Fault. The results of this study indicate that Lembang Fault intersects these lithologies and produces a permeable zone beneath the surface. Fluids derived from formation water and old water then flow through the faults to the surface. Water-rock interactions then occur and caused the carbonate dissolution then increased the water salinity. This higher salinity fluid mixes with the fluid in shallow depth until it finally appears on the surface as a spring around Lembang Fault.<p align="justify">