R.N. Hendrawan, A.J. Widiatama, M. Irsyad, A.D. Zainuddin, A. Gunawan, I. Sanjaya, R.N.F.A. Nahar, H.C. Natalia, E.R. Ogara
Gunungkasih area has several lithologies that are generated by different processes. Based on The Geological Map of Kotaagung by Amin et. al. (1993) the oldest lithologies are composed of schist, phyllite, and marble from Paleozoic followed by shale, sandstone, chert from Menanga Formation (Km) and andesitic lava, tuff from Hulusimpang Formation (Tomh) with some complicated geological history. Variations of geological products triggered the possibility of the presence of a lot of natural resources, including manganese. Manganese had been exploited around 2003-2004 by two local companies, but because the manganese deposits had not been explored yet and for a few reasons the project had been discontinued. The structural analysis will be important to find out the presence of manganese because most manganese fills in fractures, so the pattern of these deposits would be solved by structural mapping and also treated by stereonet and rosette diagrams. The fracture planes have been found in more than 500 planes and showed several types of fractures such as shear fractures, joints, quartz veins, and manganese that fill fractures which have a few directions both fault and joint directions. The most dominant fractures that are filled by manganese have been found at 120 - 130 degrees, parallel with major fault and lineament directions. The direction could be parameters and help for continued exploration further. © Published under licence by IOP Publishing Ltd.
Program Studi Teknik Geologi, Institut Teknologi Sumatera, Terusan Ryacudu Street, Way Huwi Area, Jati Agung Regency, South Lampung, Indonesia; Center of Geoscience and Mineral Technology, Institut Teknologi Sumatera, Terusan Ryacudu Street, Way Huwi Area, Jati Agung Regency, South Lampung, Indonesia; Ministry of Energy, Industry and Mineral Resource, Indonesia