Preliminary Study of the Graphite Phyllite Rock from the Luk Ulo Melange Complex, Central Java, Indonesia

Abstract

Phyllite rocks containing graphite minerals are exposed at the Luk Ulo Melange Complex (LUMC), Central Java, Indonesia. This study aims to determine the occurrence, petrographic, and geochemical characteristics of the LUMC phyllite rocks. The method used in this research consists of field observation and laboratory analysis, including petrographic and geochemical analysis using ICP AES/MS. Field observations were carried out in six locations, namely in the Karangsambung, Totogan, Duren, Kebondalem, Kebutuhjurang, and Pesangkalan villages. The phyllites are present as blocks in LUMC with 2 to >10 m in dimension and are associated with other metamorphic rocks such as greenschist, quartzite, and marble. LUMC phyllite rock has a fresh grey-black color, phyllitic foliated structure, and lepidoblastic texture. The main minerals are graphite, muscovite, quartz, and chlorite. Whole rock geochemical analysis was carried out on a phyllite sample from the Karangsambung area and showed that the major elements that dominated were SiO2 (69 wt%), Al2O3 (13 wt%), and Fe2O3 (5.78 wt%) that typical of metapelite rocks.