Electronic Theses and Dissertation

Wilayah penelitian terletak di desa kasihan, kecamatan tegalombo, kabupaten pacitan, jawa timur, yang merupakan bagian dari zona pegunungan selatan. daerah ini tersusun oleh batuan vulkanik–sedimen berumur tersier serta intrusi andesitik hingga dasitik. secara tektonik, wilayah ini dipengaruhi oleh aktivitas subduksi lempeng indo-australia terhadap lempeng eurasia, yang membentuk kondisi geologi kompleks dan prospektif bagi endapan hidrotermal. penelitian ini bertujuan untuk mengetahui kondisi geologi, persebaran zona alterasi, serta karakter mineralisasi yang berkembang sebagai basis data eksplorasi awal sumber daya mineral logam. metode penelitian meliputi pemetaan geologi permukaan berskala 1:25.000 yang didukung oleh analisis laboratorium berupa petrologi, petrografi, mineragrafi, analytical spectral device (asd), dan fire assay. hasil penelitian menunjukkan bahwa geomorfologi wilayah ini dikontrol kuat oleh struktur geologi, yang membagi daerah menjadi satuan bentang alam struktural berlereng miring dan sangat miring. tatanan stratigrafi tersusun oleh enam satuan litologi utama, yaitu tuf, batupasir, batugamping, andesit, dasit, dan breksi vulkanik. interaksi fluida hidrotermal dengan batuan samping menghasilkan tiga zona alterasi utama: filik, argilik, dan propilitik. mineralisasi bijih berkembang secara tersebar (disseminated) maupun melalui pengisian rekahan (vein/veinlet kuarsa), dengan himpunan mineral logam dasar berupa kelompok sulfida (pirit, kalkopirit, tenantit, sfalerit, galena, kovelit, kalkosit, bornit), oksida (hematit, goetit), dan karbonat sekunder (azurit, malakit). berdasarkan karakteristik alterasi, asosiasi mineral, dan kontrol struktur, genesa mineralisasi di daerah ini diklasifikasikan sebagai endapan epitermal sulfidasi menengah (intermediate sulphidation), yang merepresentasikan fase transisi pengendapan di atas sistem intrusi porfiri akibat interaksi fluida magmatik kalk-alkalin dan air meteorik. potensi sumber daya mineral tertinggi direkomendasikan pada sektor timur daerah penelitian (bukit cakrawala), yang dikontrol oleh litologi dasit dan breksi vulkanik dengan intensitas alterasi filik.

The research area is located in Kasihan Village, Tegalombo District, Pacitan Regency, East Java, which is part of the Southern Mountains Zone. This area is composed of Tertiary volcanic-sedimentary rocks and andesitic to dacitic intrusions. Tectonically, this region is influenced by the subduction activity of the Indo-Australian Plate beneath the Eurasian Plate, creating a complex geological setting prospective for hydrothermal deposits. This study aims to determine the geological conditions, the distribution of alteration zones, and the characteristics of mineralization as a database for the preliminary exploration of metallic mineral resources. The research method involves surface geological mapping at a scale of 1:25,000, supported by laboratory analyses including petrology, petrography, mineragraphy, Analytical Spectral Device (ASD), and Fire Assay.The results show that the geomorphology of this region is strongly controlled by geological structures, which divide the area into Moderately Sloping and Steeply Sloping Structural Landform Units. The stratigraphic framework consists of six main lithological units: Tuff, Sandstone, Limestone, Andesite, Dacite, and Volcanic Breccia. The interaction of hydrothermal fluids with the wall rocks produced three main alteration zones: phyllic, argillic, and propylitic. Ore mineralization occurs as disseminated bodies and fracture fillings (quartz veins/veinlets), comprising base metal assemblages of sulfides (pyrite, chalcopyrite, tennantite, sphalerite, galena, covellite, chalcocite, bornite), oxides (hematite, goethite), and secondary carbonates (azurite, malachite).Based on the alteration characteristics, mineral associations, and structural controls, the genesis of mineralization in this area is classified as an intermediate sulfidation epithermal deposit. This represents a transitional depositional phase above a porphyry intrusion system caused by the interaction of calc-alkaline magmatic fluids and meteoric water. The highest mineral resource potential is recommended in the eastern sector of the study area (Cakrawala Hill), which is controlled by Dacite and Volcanic Breccia lithologies with intense phyllic alteration.