GEOLOGY AND HYDROGEOLOGY OF BRANDS AREA, KARO REGENCY AND SIMALUNGUN, NORTH SUMATRA.

• Main Author: 'ayyub Khairiansyah, Muhammad
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/70011
• Institution: Institut Teknologi Bandung

The research area is located in Merek District, Karo Regency and Silimakuta District, Simalungun Regency, North Sumatra. Geographically, the research area is located at UTM coordinates 443,000 – 451,500 mE and 317,000-326,000 mN (WGS 1984, 47 N zone). The research area is 76.5 km2. Based on the BMB classification, the research area can be divided into three geomorphological units, Toba Caldera Wall Hills Unit, Tandukbenua Parasitic Volcano Cone Unit, and Tongging Alluvial Plain Unit. The research area is in Young Geomorphic stage. Stratigraphically, the research area can be divided into seven non-formal rock units which were formed during Late Carboniferous – Recent, deposited in open shallow marine to fluvial environment. The sequence from older to younger strata are Phyllite Unit, Sandstone Unit, Pyroclastic Breccia Unit, Tuff 1 Unit, Tuff 2 Unit, Andesitic Lava Unit and Alluvial Deposit Unit. Geological structures in the research area are Toba Caldera Normal Fault, Pintuangin Normal Fault, Gajahbobok Normal Fault, and Sibolangit Normal Fault. These structures were formed in Late Pleistocene, after Tuff 2 Unit was deposited. Aquifer in the research area is in the weathered Phyllite Unit, Sandstone Unit, Pyroclastic Breccia Unit, Tuff 2 Unit, weathered Andesitic Lava Unit , and Alluvial Deposit Unit. The type of aquifer in the research area is unconfined aquifer. All water from springs and dug well in the research area are suitable for drinking according to PERMEN No.492/MENKES/PER/IV/2010 based on pH and TDS value criteria. The pH value ranges from 6.6 – 7.34 while TDS value ranges from 36-120 mg/L.