Studi alterasi hidrotermal yang berasosiasi dengan mineralisasi logam di daerah Sangka Ropi dan sekitarnya, kecamatan Sa'dan, Tana Toraja Utara, provinsi Sulawesi Selatan
P Permasalahan yang menarik di daerah penelitian berdasarkan penelitian terdahuluadalah batuan-batuannya sudah terubah akibat proses alterasi hidrotermal danbanyak ditemukan mineralisasi bijih. Penelitian ini dilakukan untuk mempelajarialterasi akibat proses hidrotermal, mengetahui penyebaran zona alterasi danhubungannya terhadap mineralisasi logam. Metode penelitian yang dilakukan ialahPemetaan Geologi dan Analisis Laboratorium (analisis petrografi, analisismineragrafi dan analisis XRD). Batuan di daerah penelitian terdiri dari atas 4 satuan,yaitu satuan breksi vulkanik berwarna kuning kecoklatan, mengalami alterasidengan komposisinya berasal dari beberapa fragmen. Setelah itu dillanjutkan denganpengendapan lava andesit yang secara umum berwarna abu-abu dan telahmengalami proses alterasi berumur Oligosen hingga Miosen Awal. Diikuti olehpengendapan satuan batuan tuf yang berwarna putih pada daerah selatan daerahpenelitian yang mengalami proses alterasi. Terakhir, terjadinya pengendapan satuanbatuan intrusi granit yang berwarna hijau kecoklatan pada daerah barat, berumurMiosen Akhir hingga Pliosen. Berdasarkan analisis petrografi, mineragrafi, dananalisis XRD pada sampel batuan, hadir 4 zona alterasi di daerah penelitian yaituzona alterasi dengan kisaran suhu sekitar 280°-320°C ialah zona kuarsa-kloritepidot,zona klorit-epidot-karbonat-pirit yang diinterpretasikan hadir pertama dandengan kisaran suhu sekitar 260°-320°C ialah zona kuarsa-serisit-pirit diikutidengan zona kuarsa-ilit/smektit-karbonat muncul diakhir dengan kisaran temperatur120°-220°C dan zona kuarsa-adularia (silisifikasi) temperatur berkisar 80°-120°Cdengan pH lebih rendah.
A An interesting problem in the research area based on previous research is that therocks have been changed due to hydrothermal alteration and many oremineralization have been found. This research was conducted to study alterationdue to hydrothermal processes, to know the distribution of alteration zones andconnected to metal mineralization. The research method used is the Mapping ofGeology and Laboratory Analysis (petrographic analysis, mineragraphy analysisand XRD analysis). The rocks in the study area consists of 4 units, namely volcanicbreccia is brownish in color and have undergone alteration process with a severalfragments. Afterwards proceed with the deposition unit andesite lava that aregenerally gray in color and has undergone alteration process, aged Oligocene toEarly Miocene. And is followed by the deposition of tuff units are white color insouth area of research and had an undergone alteration process. Last, there is thedeposition of granite intrusion units are green to brown in west area, aged LateMiocene to Pliosen. Based on petrography analysis, mineragraphy, and XRDanalysis on rock samples, present 4 alteration zones in the study area, namely withtemperature range around 280°-320°C with zoning quartz-chlorite-epidote as afirst zone, second zone is zoning chlorite-epidote-carbonate, which is areinterpreted appear first and with temperature range around 260°-320°C is zoningquartz-sericite-pyrite, followed by zoning quartz-ilite/smectite-carbonate withtemperature range around 120°-220°C and zoning quartz-adularia (silisification)temperature range around 80°-120°C and a lower pH.