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All Journal Bulletin of Scientific Contribution : Geology IJOG : Indonesian Journal on Geoscience Journal of Geoscience, Engineering, Environment, and Technology Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources) Buletin Sumber Daya Geologi Jurnal Geologi Kelautan: Media Hasil Penelitian Geologi Kelautan Jurnal Sosial Ekonomi Pekerjaan Umum Journal of Geoscience Engineering and Energy (JOGEE) Prosiding Seminar Nasional Rekayasa Teknologi Industri dan Informasi ReTII Aceh International Journal of Science and Technology Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources) Journal of Geosciences and Applied Geology
Mega Fatimah Rosana
Faculty of Geology, Padjadjaran University, Jln. Raya Bandung - Sumedang Km. 21
Aerospace Engineering Agriculture, Biological Sciences & Forestry Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Transportation

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High Sulphidation Mineralization and Advanced Argillic Alteration within Concealed Gajah Tidur Porphyry, Grasberg District, Papua Bensaman, Benny; Rosana, Mega Fatimah; Yuningsih, Euis Tintin
Indonesian Journal on Geoscience Vol. 11 No. 1 (2024)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.11.1.15-33

Abstract

High sulphidation (HS) mineralization and associated advanced argillic alteration have been intersected by three drill holes below the Grasberg porphyry Cu-Au deposit, known as the Gajah Tidur prospect. The prospect is located between 1,500 ̶ 2,750 m level, in Grasberg District, Papua, Indonesia. The holes are of KL98-10-21, KL98-10-22, and GRD39-08 which intersected 3.4 Ma Gajah Tidur monzonite, Grasberg Igneous Complex, the wall rocks of Kembelangan, and New Guinea Limestone Group. This research aims to determine the characteristics of high sulphidation mineralization associated with advanced argillic alteration at Gajah Tidur. Petrographic, XRD, SEM, fluid inclusion, and XRF (geochemical) analyses were applied to identify the mineralogy, geochemistry, and ore fluid properties. The major element plots show a differentiated intrusion. The alteration consists of potassic materials composed of biotite and K-feldspar, overprinted by phyllic and advanced argillic ones typified by alunite, pyrophyllite, and kaolinite. The high sulphidation mineralization characterized by pyrite-covellite, chalcopyrite-chalcocite, enargite, and digenite is also present. Fluid inclusion homogenization temperature of mineralized quartz vein ranges from 393 to 542°C, indicating a magmatic fluid origin predominantly. Two distinct porphyry systems, consisting of the Gajah Tidur Cu-Mo and the Main Grasberg Cu-Au porphyry systems are emplaced at the Gajah Tidur level. Advanced argillic is less intense compared to a pervasive phyllic alteration, overprinting the stockwork and surrounding rocks, emplaced at the upper part of quartz stockwork. It is possibly associated with a late stage of Gajah Tidur porphyry hydrothermal fluids which became cooler and highly acidic. Similar to other porphyry systems such as Oyu Tolgoi in Mongolia, the Gajah Tidur porphyry did not have its hydrothermal fluid ascent to the surface to form lithocap. Instead, the ascending fluids cooled at shallower depths resulting in the formation of advanced argillic alteration.
Secondary Enrichment of REE in Weathered Granite, South Bangka, Indonesia Tampubolon, Armin; Syafri, Ildrem; Rosana, Mega Fatimah; Yuningsih, Euis Tintin
Indonesian Journal on Geoscience Vol. 11 No. 1 (2024)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.11.1.141-165

Abstract

Rare earth elements (REEs) are essential materials for the manufacture of advanced technology. Secondary REE indications were found in alluvial and lateritic tin deposits within Southeast Asia Tin Belt. This study aims at the REE enrichment of weathering profiles underlain by Toboali Pluton of the main range S-type granite of this belt. Granite and weathering samples were collected and analyzed using XRF, ICP-MS/OES, XRD, SEM-EDX, and EPMA. The Chondrite-normalized REE patterns of granite in Toboali showed enrichment in REE with the highest value of 1,126 ppm. The Toboali Pluton is enriched in LREE and depleted in HREE. The enrichment of REE from the upper to lower horizon of weathering profiles was pointed out by the increase in REE values from a range of 156-188 ppm (horizon B) to 196-268 ppm (horizon C) in Toboali, and from a range of 230-330 ppm (horizon B) to 342-450 ppm (horizon C) in Air Gegas. These coincided with the presence of kaolinite with elevated REE and CeO2 in horizon C of weathering profile. Leaching test result proved that kaolinite plays a role in REE enrichment in the weathering profile through ion adsorption mechanisms in the Air Gegas. The weathering process of REE fluoro-carbonate (bastnäsite-(Ce)) and parisite-(Ce) in granite is believed to contribute in enrichment due to its high dissolution rate, which enhances kaolinite adsorption. In contrast, REE phosphates such as monazite-(Ce) and xenotime-(Y), because of their strong resistance and low solubility, are thought to be only slightly soluble, and most of these minerals remain in Toboali weathering products.
Fluid Inclusion and Mineralization of Base Metals in Cretaceous Metamorphic Rocks, in Jiwo Hills, Bayat, Klaten, Central Java Maulana, Fivry Wellda; Rosana, Mega Fatimah; Yuningsih, Euis Tintin; Haryanto, Agus Didit; Purwanto, Heru Sigit; Rakhman, Arie Noor
Indonesian Journal on Geoscience Vol. 11 No. 2 (2024)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.11.2.251-267

Abstract

The lack of mineralization research on metamorphic rocks in Java, especially in the Jiwo area, is part of the research interest. The host rock of ore mineralization in the Jiwo area is Cretaceous metamorphic rock located in the hilly area of Jiwo, Klaten, Central Java. The presence of chlorite, actinolite, quartz, epidote, and garnet minerals indicates the metamorphic facies of greenschist. Meanwhile, the presence of glaucophane, quartz, and epidot minerals is a metamorphic facies of blueschist. The metamorphic rock research method was carried out in several stages: 1. Observation; 2. Field data collection, including mapping of metamorphic rock distribution, general geological conditions and rock sampling; and 3. Laboratory analysis. Laboratory analysis testing consists of petrography, ore microscopy, geochemistry (AAS), and fluid inclusion. Alterations that develop in the researched area are in the form of propylitic (chlorite, calcite, epidote), argillic, and silicification (quartz, graphite, calcite, carbonate minerals). Ore microscopy analysis has identified the presence of mineral sulfide such as pyrite, chalcopyrite, bornite, galena, and covellite. In addition, galena was found covered with chalcopyrite. Based on AAS analysis on mineralized metamorphic rocks, Au levels are 0.001 - 0.008 g/t, Ag 0.1 - 2.4 g/t, Cu 4 - 75 g/t, Zn 14 - 166 g/t, and Pb 11 - 60 g/t. The inclusion of fluid from the discordant vein was obtained with a homogenization temperature (Th) of 312 - 435 0C, with a salinity of 1.95 - 5.05 wt. % eq. with isothermal mixing and heating depressurization conditions. The isothermal mixing process is a mixture of meteoric fluids and metamorphic fluids. Meanwhile, heating depressurization occurs during subduction, so that the temperature is relatively high. The homogenization temperature (Th) of the concordant vein ranges from 168.5 - 296.55 °C, with a salinity of 1.95 -12.6 wt% NaCl eq. A salinity of 12 wt% NaCl is formed due to liquids that are aquos trapped at high pressure and temperature conditions and the devolatilization process that occurs during subduction. Based on the plotting of the homogenization temperature range and the salinity of fluid inclusion, which is 168.5 - 4350C and 1.95 - 12.6 wt% NaCl eq, the type of deposits in the study area is in the range of Au lode or orogenic deposits. The existence of two homogenization clusters in the Jiwo Hill is estimated to be part of the process of forming the blueschist facies with greenschist which is shown in the retrograde actinolite in the glaucophane epidote schist rock which is part of the blueschist facies.
Geologi, Genesis dan Karakteristik Endapan Laterit Bauksit di Daerah Melugai, Kalimantan Barat Muhammad Hery Setiyawan; Rosana, Mega Fatimah; Hutabarat, Johanes; Hartono, Hill Gendoet
Retii 2025: Prosiding Seminar Nasional ReTII ke-20 (Edisi Penelitian)
Publisher : Institut Teknologi Nasional Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Endapan bauksit laterit yang ditemukan di Desa Melugai, Kalimantan Barat merupakan bagian dari zona laterit prospektif. Penelitian ini bertujuan mengkaji kondisi geologi dan genesis endapan yang mempengaruhi karakteristik bauksit. Metode yang digunakan meliputi pemetaan geologi, analisis petrografi, dan uji laboratorium (XRD dan XRF). Daerah Melugai tersusun oleh batuan Malihan Pinoh dengan unit metatuf dan metaandesit yang berumur Trias. Secara geomorfologi, wilayah ini berupa perbukitan bergelombang landai hingga miring dengan pola aliran dendritik. Pembentukan bauksit laterit dikendalikan oleh jenis batuan induk, waktu, iklim tropis, dan geomorfologi landai, dimana proses lateritisasi mengintensifkan pelapukan dan pelindian unsur larut (Na, K, Ca) sehingga meninggalkan residu kaya aluminium hidroksida (Al(OH)₃) yang mengeras menjadi bauksit. Endapan bauksit di Melugai terbagi menjadi dua tipe berdasarkan batuan induknya. Hasil analisis XRD menunjukkan mineral dominan berupa gibbsite, hematite, geothite, kaolinite, quartz, dan sodalite. Analisis XRF menyimpulkan perbedaan kualitas yang signifikan. Bauksit dari batuan induk metatuf memiliki kadar Al₂O₃ rata-rata 47,53% (kualitas medium grade). Sedangkan bauksit dari batuan induk metaandesit memiliki kadar Al₂O₃ rata-rata 32,25% (kualitas low grade). Disimpulkan bahwa bauksit yang bersumber dari batuan induk metatuf memiliki kualitas yang lebih baik dan tingkat laterisasi yang lebih kuat.
Co-Authors Achmad Noerkhaerin Putra Achmad Rizal Adi Hardiyono, Adi Adjat Sudradjat Adjat Sudrajat Agus Didit Haryanto -, Agus Didit Haryanto Akhmad Fauzan Alamsyah, Irpan Almun Madi Andi Kurniawan Angga Syahputra, Muhammad Eko Ar-rouf, Ferdian Budi Arie Noor Rakhman Asri Arifin Asrial, Nouval Muamar Aton Patonah, Aton Azzaenuri, Mohammad Fachri Bahtiar, Wisnu Indra Bensaman, Benny Boy Yoseph Cahya Sunan Sakti Syah Alam Cecep Yandri Sunarie, Cecep Yandri Chiyonobu, Shun Cipta Endyana Dicky Muslim Diwantara, Raja Hertansyah Eko Tri Sumarnadi Agustinus Emi Sukiyah Ernowo Ernowo Euis Tintin Yuningsih Fachrudin, Kurnia Arfiansyah Fadhlurrohman Putrananda, Aditya Faizal, Reza Mochammad Faizal, Reza Mochammad Faurine, Nurul Rizma Fitriany, Ria Fivry Wellda Maulana Hafidhah Nurul Haq Heriawan, Mohammad N Hernadi, Deni Heru Sigit Purwanto Hill Gendoet Hartono Hiroharu Matsueda Ildrem Syafri Indra Kusuma, Riko Ardiansyah Indrakususma, Riko Ardiansyah Indrakususma, Riko Ardiansyah Ismail, Fajar Iyan Haryanto, Iyan Johanes Hutabarat Kamaruddin, Hashari Kamaruddin, Hashari Kemala Wijayanti, Kemala Khoerunisa, Resa Kurnia Arfiansyah, Kurnia Lia Jurnaliah Lili Fauzielly Marbun, Ardiansyah Maulana, Muhammad Hafidz Meiriyanto, Fernandy Mohamad Nur Heriawan Muhammad Hery Setiyawan Nana Sulaksana Nordin, Nazihah Nugraha, Katon Sena Ajie Nurahmah, Siti Chusnul Chatimah Nurzakiyah, Halimah Pradnya Paramarta Raditya Rendra Pratiwi, Prisca Nurul Purwaiswanto, Bambang Antoro Putri, Nisrina Nadellia Raden Isnu Hajar Sulistyawan, Raden Isnu Hajar Rangga Suteja, Rangga Rezky, Yuanno Rezky, Yuanno Ridho Kresna Wattimena Ridho Kresna Wattimena, Ridho Kresna Rinawan, Fiandri Indragunawan Rinawan, Fiandri Indragunawan Rompo, Ahmad Iryanto Rompo, Iryanto Ruswanto, . Santoso, STJ Budi Saputra, Dwie H. Sentosa*, Millati Amalia Soepriadi, Soepriadi Soepriadi, Soepriadi Sukaesih Sukaesih, Sukaesih Sukardan Tawil SUMARWAN, FIRMAN Suwandhi, Awang Suwandhi, Awang SYAH, MOHAMAD AKBAR Tampubolon, Armin Undang Mardiana Wibowo, Setiyo Widyariestha, Mira Winantris Winantris Wirdan, Muhammad Faisal Yanuar, Yerry Yuningsih, Euis Tintint Zakaria, Zulfiadi Zuzy Anna