PETROGENESIS AND MINERALISASI STUDY OF OPHIOLITE COMPLEX AT MOLAWE—ANDOWIA NORTH KONAWE REGENCY SULAWESI TENGGARA PROVINCE

• Main Author: ALI KAYUM PINO (NIM: 22014046), ABD.
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/20656
• Institution: Institut Teknologi Bandung

Ophiolite complex is a collection of mafic-ultramafic rocks and pelagic deposits. One of the non-complete Cretaceous Ophiolite Complex is located in Molawe-Andowia regions as the Eastern Sulawesi Ophiolite Belt, which is prominently going through traverse-oblique in westward on the Mesozoic-Paleogen sedimentary rocks in the Southeast Sulawesi Continent. The formation of ophiolite rock in Southeast Sulawesi is type of Mid Oceanic Ridge (MOR) ophiolite and the presence of sole metamorphic gradients and thin alluvial deposits, as an indication of over-place process ophiolite complex in the study area has undergone obduction belonging to the type Tethyan ophiolite. Studies of ultramafic – mafic rocks use several stages of analysis, including geological mapping, petrography, mineragraphy and magnetic susceptibility analysis of rocks. Geological mapping obtained four lithological units and some of them have strong tectonic deformations. Petrographic study to analyse texture patterns such as lamellae and bleb-like extraction, rock-forming minerals such as phosphate fosterite, diopside, augite, enstatite formed at high temperatures of 1000˚C-1890 ˚C, and paragenesis mineral in the form of fosterite replaced by serpentine and subsequently replaced by talk which is further filled by magnetite, the data is supported by intensive magnetized susceptibility of rocks with a value range of 5.71-10.59 x 10-3 SI. Mineragraphy analyzes include euhedral-subhedral chromite with podiform structure which is the result of the initial magmatic process. These analyzes are helpful in determining ophiolite sequence and tectonic environment of ultramafic-mafic rock formation. Distribution of chromite, magnetite and spinel is directed in south, northeast, and east which are dominant in harsburgite rocks. The results of fosterite and diopside mineral analysis in temperature diagrams proved the formation of ultramafic rocks (lersolite) in the lower mantle and serpentine analysis, proving serpentine minerals formed in the tectonic environments of the Mid-Oceanic Ridge (MOR).