BASE METAL OCCURRENCE IN INTRUSIVES ROCK FROM SASSAK REGION TORAJA PROVINCE SOUTH SULAWESI

Abstract

Study on the occurrence of base metals (Pb, Zn, Cu, Fe, Mn and Sc) in intrusive rocks at Sasak area of Toraja Regency, South Sulawesi Province has been conducted. The study aims to obtain information about the characteristic of the intrusive rocks and the concentration of base metals in the area along with the geological processes controlling the formation of these metals. The analytical method used in this study is petrographic analysis by observing ten intrusive rock samples to determine rock type, texture, structure and mineral composition. Base metal element concentration is obtained by XRF method on four samples. The results show that the intrusive rock types are diorite, grey-coloured in fresh and greyish-brown in weathered condition, holocrystalline and phaneritic texture, euhedral-subhedral, equigranular, massive structures with mineral compositions consisting of plagioclase, pyroxene, hornblende, biotite, small amount of quartz and opaque minerals. Quartz veins and some alteration minerals found in several samples indicate the presence of hydrothermal fluid and alteration process. The geochemical analysis shows that the base mental content of Pb ranges from 17 to 39 ppm, Cu (88 - 179 ppm), Fe (5.31 - 6.04%), Mn (610 - 1040 ppm), Zn (48 - 84 ppm) and Sc (8-10 ppm). The most enriched element is manganese (Mn) with the highest concentration found in sample ST 5 VEIN in the amount of 1040 ppm. The base metal found in intrusive rocks were formed through a hydrothermal process as evidenced by the presence of alteration minerals and sulfide minerals such as pyrite and chalcopyrite.