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INTERPRETASI SEBARAN MINERALISASI LOGAM EMAS BERDASARKAN NILAI RESISTIVITY MENGGUNAKAN METODE GEOLISTRIK KONFIGURASI WENNER Malik, Maulana; Nur, Irzal; Ilyas, Asran
Jurnal Penelitian Geosains Vol 10, No 2 (2014)
Publisher : Jurnal Penelitian Geosains

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Abstract

The limitation of data and information about distribution of gold mineralization based on the value of resistivity in the hosted rock on WIUP exploration PT. Indi Karya Anugerah which is located in Long Iram, West Kutai, East Borneo becomes the background of this study. The purpose of this study is expected to find the indications of gold mineralization anomalies based on the geophysical data of geoelectrical resistivity value hosted rock, rock contacts, mineralization and the sub-surface distribution. Vertical geoelectrical resistivity inversion using Wenner configuration for eight line of one with the position of the potential electrode and current electrode arranged from C1-P1-P2-C2. Based on the result of resistivity interpretation using software RES2Dinv showed that the lowest resistivity value of materials is 1.23Ωm till the highest one is 119085Ωm with rocks encountered indicated as Latite which was exposed, had a high resistivity. Outcrop of alteration area was found with relatively low resistivity and based on its physical characteristics as well as indication of gold occurrences in rock samples with grade of 2.01 ppm on line 01-line 02 and 2.27ppm on line 08 which were the analysis result in laboratory.Keywords: Survey review, alteration, resistivity, software RES2Dinv, anomalies
Metamorphic rock-hosted orogenic gold deposit style at Bombana (Southeast Sulawesi) and Buru Island (Maluku): Their key features and significances for gold exploration in Eastern Indonesia Idrus, Arifudin; Prihatmoko, Sukamandaru; Harjanto, Ernowo; Meyer, Franz Michael; Nur, Irzal; Widodo, Wahyu; Agung, Lia Novelia
Journal of Geoscience, Engineering, Environment, and Technology Vol 2 No 2 (2017): JGEET Vol 02 No 02 : June (2017)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1215.235 KB) | DOI: 10.24273/jgeet.2017.2.2.291

Abstract

In Indonesia, gold is commonly mined from epithermal-, porphyry-, and skarn-type deposits that are commonly found in volcanic belts along island arcs or active continental margin settings. Numerous gold prospects, however, were recently discovered in association with metamorphic rocks. This paper focuses on metamorphic rock-hosted gold mineralization in Eastern Indonesia, in particular the Bombana (SE Sulawesi) and Buru Island (Maluku) prospects. At Bombana, gold-bearing quartz-veins are hosted by the Pompangeo metamorphic complex. Sheared, segmented veins vary in thickness from 2 cm to 2 m. Gold is mainly present in the form of ‘free gold’ among silicate minerals and closely related to cinnabar, stibnite, tripuhyite, and in places, minor arsenopyrite. The gold distribution is erratic, however, ranging from below detection limit up to 134 g/t. At least three generations of veins are identified. The first is parallel to the foliation, the second crosscuts the first generation of veins as well as the foliation, and the late-stage laminated deformed quartz-calcite vein represents the third mineralization stage. The early veins are mostly massive to crystalline, occasionally brecciated, and sigmoidal, whereas the second-stage veins are narrower than the first ones and less subjected to brecciation. Gold grades in the second- and third-stage veins are on average higher than that in the earlier veins. Microthermometric and Raman spectrometric studies of fluid inclusions indicate abundant H2O-NaCl and minor H2O-NaCl-CO2 fluids. Homogenization temperatures and salinities vary from 114 to 283 ºC and 0.35 to 9.08 wt.% NaCl eq., respectively. Crush-leach analysis of fluid inclusions suggests that the halogen fluid chemistry is not identical to sea water, magmatic or epithermal related fluids, but tends to be similar to fluids in mesothermal-type gold deposits. In Buru Island (Gunung Botak and Gogorea prospects), two distinct generations of quartz veins are identified. Early quartz veins are segmented, sigmoidal discontinuous and parallel to the foliation of the host rock. This generation of quartz veins is characterized by crystalline relatively clear quartz, and weakly mineralized with low sulfide and gold contents. The second type of quartz veins occurs within the ‘mineralized zone’ of about 100 m in width and ~1,000 m in length. Gold mineralization is intensely overprinted by argillic alteration. The mineralization-alteration zone is probably parallel to the mica schist foliation and strongly controlled by N-S or NE-SW-trending structures. Gold-bearing quartz veins are characterized by banded texture particularly following host rock foliation and sulphide banding, brecciated and rare bladed-like texture. Alteration types consist of propylitic (chlorite, calcite, sericite), argillic and carbonation represented by graphite banding and carbon flakes. Ore mineral comprises pyrite, native gold, pyrrhotite, and arsenopyrite. Cinnabar and stibnite are present in association with gold. Ore chemistry indicates that 11 out of 15 samples yielded more than 1 g/t Au, in which 6 of them graded in excess of 3 g/t Au. All high-grade samples are composed of limonite or partly contain limonitic material. This suggests the process of supergene enrichment. Interestingly, most of the high-grade samples contain also high concentrations of As (up to 991ppm), Sb (up to 885ppm), and Hg (up to 75ppm). Fluid inclusions in both quartz vein types consist of 4 phases including L-rich, V-rich, L-V-rich and L1-L2-V (CO2)-rich phases. The mineralizing hydrothermal fluid typically is CO2-rich, of moderate temperature (300-400 ºC), and low salinity (0.36 to 0.54 wt.% NaCl eq). Based on those key features, gold mineralization in Bombana and Buru Island tends to meet the characteristics of orogenic, mesothermal types of gold deposit. Metamorphic rock-hosted gold deposits could represent the new targets for gold exploration particularly in Eastern Indonesia.
THE METAMORPHIC ROCK-HOSTED GOLD MINERALIZATION AT BOMBANA, SOUTHEAST SULAWESI: A NEW EXPLORATION TARGET IN INDONESIA Idrus, Arifudin; Fadlin, Fadlin; Prihatmoko, Sukmandaru; Warmada, I Wayan; Nur, Irzal; Meyer, Franz Michael
Jurnal Geologi dan Sumberdaya Mineral Vol 22, No 1 (2012): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

Placer gold has been discovered in Bombana, SE-Sulawesi, Indonesia. The placer gold is not associated with volcanic rock-related gold deposits. This paper discusses the primary gold mineralization as the source of the placer gold. The placer gold is possibly derived from gold-bearing quartz veins hosted by Pompangeo Metamorphic Complex (PMC). Pyrite, chalcopyrite, cinnabar, stibnite and tripuhyite are present. Sheared, segmented vein varies in thickness from 2 cm to 2 m. The veins contain erratic gold in various grades from below detection limit (0.005 g/t) to 134 g/t. At least three generations of veins are identified. The first is parallel to the foliations, the second crosscuts the first generation of veins/foliations, and the third is of laminated deformed quartz+calcite veins at the late stage. The first veins are mostly massive to crystalline, occasionally brecciated and sigmoidal, whereas the second veins are narrower than the first and relatively brecciated. Gold grades in the second and third veins are relatively higher than that in first veins. Fluid inclusion study of quartz veins indicates abundant H2O-NaCl and a small amount of H2O-NaCl-CO2 inclusions. Temperature of homogenization (Th) and salinity of the first vein vary from 184.7 to 245.3 ºC and 5.26 to 9.08 wt.% NaCl eq., respectively. The second generation vein was originated at Th of 132.1-283.4 ºC and salinity of 3.55-5.86 wt.%NaCl eq., whereas the third generation vein formed at lowest Th varying from 114 to 176ºC and less saline fluid at salinity range between 0.35 and 4.03 wt.% NaCl eq. Gold is mainly identified in the form of 'free gold' among silicate minerals. Mineralogically, gold is closely related to cinnabar, stibnite, tripuhyite and possibly minor arsenopyrite. Metamorphogenic gold deposits would be the new target of gold exploration in Indonesia.Keyword: Gold mineralization, orogenic-type, Bombana, Southeast Sulawesi, Indonesia
Metamorphic rock-hosted orogenic gold deposit style at Bombana (Southeast Sulawesi) and Buru Island (Maluku): Their key features and significances for gold exploration in Eastern Indonesia Arifudin Idrus; Sukamandaru Prihatmoko; Ernowo Harjanto; Franz Michael Meyer; Irzal Nur; Wahyu Widodo; Lia Novelia Agung
Journal of Geoscience, Engineering, Environment, and Technology Vol. 2 No. 2 (2017): JGEET Vol 02 No 02 : June (2017)
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1215.235 KB) | DOI: 10.24273/jgeet.2017.2.2.291

Abstract

In Indonesia, gold is commonly mined from epithermal-, porphyry-, and skarn-type deposits that are commonly found in volcanic belts along island arcs or active continental margin settings. Numerous gold prospects, however, were recently discovered in association with metamorphic rocks. This paper focuses on metamorphic rock-hosted gold mineralization in Eastern Indonesia, in particular the Bombana (SE Sulawesi) and Buru Island (Maluku) prospects. At Bombana, gold-bearing quartz-veins are hosted by the Pompangeo metamorphic complex. Sheared, segmented veins vary in thickness from 2 cm to 2 m. Gold is mainly present in the form of ‘free gold’ among silicate minerals and closely related to cinnabar, stibnite, tripuhyite, and in places, minor arsenopyrite. The gold distribution is erratic, however, ranging from below detection limit up to 134 g/t. At least three generations of veins are identified. The first is parallel to the foliation, the second crosscuts the first generation of veins as well as the foliation, and the late-stage laminated deformed quartz-calcite vein represents the third mineralization stage. The early veins are mostly massive to crystalline, occasionally brecciated, and sigmoidal, whereas the second-stage veins are narrower than the first ones and less subjected to brecciation. Gold grades in the second- and third-stage veins are on average higher than that in the earlier veins. Microthermometric and Raman spectrometric studies of fluid inclusions indicate abundant H2O-NaCl and minor H2O-NaCl-CO2 fluids. Homogenization temperatures and salinities vary from 114 to 283 ºC and 0.35 to 9.08 wt.% NaCl eq., respectively. Crush-leach analysis of fluid inclusions suggests that the halogen fluid chemistry is not identical to sea water, magmatic or epithermal related fluids, but tends to be similar to fluids in mesothermal-type gold deposits. In Buru Island (Gunung Botak and Gogorea prospects), two distinct generations of quartz veins are identified. Early quartz veins are segmented, sigmoidal discontinuous and parallel to the foliation of the host rock. This generation of quartz veins is characterized by crystalline relatively clear quartz, and weakly mineralized with low sulfide and gold contents. The second type of quartz veins occurs within the ‘mineralized zone’ of about 100 m in width and ~1,000 m in length. Gold mineralization is intensely overprinted by argillic alteration. The mineralization-alteration zone is probably parallel to the mica schist foliation and strongly controlled by N-S or NE-SW-trending structures. Gold-bearing quartz veins are characterized by banded texture particularly following host rock foliation and sulphide banding, brecciated and rare bladed-like texture. Alteration types consist of propylitic (chlorite, calcite, sericite), argillic and carbonation represented by graphite banding and carbon flakes. Ore mineral comprises pyrite, native gold, pyrrhotite, and arsenopyrite. Cinnabar and stibnite are present in association with gold. Ore chemistry indicates that 11 out of 15 samples yielded more than 1 g/t Au, in which 6 of them graded in excess of 3 g/t Au. All high-grade samples are composed of limonite or partly contain limonitic material. This suggests the process of supergene enrichment. Interestingly, most of the high-grade samples contain also high concentrations of As (up to 991ppm), Sb (up to 885ppm), and Hg (up to 75ppm). Fluid inclusions in both quartz vein types consist of 4 phases including L-rich, V-rich, L-V-rich and L1-L2-V (CO2)-rich phases. The mineralizing hydrothermal fluid typically is CO2-rich, of moderate temperature (300-400 ºC), and low salinity (0.36 to 0.54 wt.% NaCl eq). Based on those key features, gold mineralization in Bombana and Buru Island tends to meet the characteristics of orogenic, mesothermal types of gold deposit. Metamorphic rock-hosted gold deposits could represent the new targets for gold exploration particularly in Eastern Indonesia.
INTERPRETASI SEBARAN MINERALISASI LOGAM EMAS BERDASARKAN NILAI RESISTIVITY MENGGUNAKAN METODE GEOLISTRIK KONFIGURASI WENNER Maulana Malik; Irzal Nur; Asran Ilyas
Jurnal Penelitian Geosains Vol. 10 No. 2 (2014)
Publisher : Jurnal Penelitian Geosains

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

Abstract

The limitation of data and information about distribution of gold mineralization based on the value of resistivity in the hosted rock on WIUP exploration PT. Indi Karya Anugerah which is located in Long Iram, West Kutai, East Borneo becomes the background of this study. The purpose of this study is expected to find the indications of gold mineralization anomalies based on the geophysical data of geoelectrical resistivity value hosted rock, rock contacts, mineralization and the sub-surface distribution. Vertical geoelectrical resistivity inversion using Wenner configuration for eight line of one with the position of the potential electrode and current electrode arranged from C1-P1-P2-C2. Based on the result of resistivity interpretation using software RES2Dinv showed that the lowest resistivity value of materials is 1.23Ωm till the highest one is 119085Ωm with rocks encountered indicated as Latite which was exposed, had a high resistivity. Outcrop of alteration area was found with relatively low resistivity and based on its physical characteristics as well as indication of gold occurrences in rock samples with grade of 2.01 ppm on line 01-line 02 and 2.27ppm on line 08 which were the analysis result in laboratory.Keywords: Survey review, alteration, resistivity, software RES2Dinv, anomalies
Geothermal Fluid Characterisics based on Geochemical Analysis of Hot Water in The Wawolesea Area, North Konawe Regency Southeast Sulawesi Province: Karakteristik Fluida Panas Bumi Berdasarkan Analisis Geokimia Air Panas Daerah Wawolesea Kabupaten Konawe Utara Sulawesi Tenggara Rizky Nurul Aulia; Irzal Nur; Asran Ilyas
JURNAL GEOCELEBES Vol. 6 No. 1: April 2022
Publisher : Departemen Geofisika, FMIPA - Universitas Hasanuddin, Makassar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20956/geocelebes.v6i1.19672

Abstract

North Konawe Regency is an area with interesting geothermal potential to be studied. The observed geothermal potential manifestation is located in the Wawolesea area through the collection and analysis of three hot spring samples. This study aims to determine the characteristics of geothermal fluids, namely the type and origin of the fluid by conducting geochemical analysis on samples of hot springs in the study area which further shows the content of elements and chemical compounds and their respective concentrations. The analysis in this research is Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) to obtain B and Li concentrations, conductivity meter to obtain Cl concentration, visible spectroscopy method for SO4 concentration and HCO3 concentration measured by acid-base titration. The results showed that the type of hot springs in the study area was included in the Chloride type with a percentage of 81.8156%-83.3976% with a pH value of 6.7-7.4 and a hot spring temperature of 50-54°C then plotted into trilinear diagram. The Cl-Li-B Ternanry diagram shows that the source of the fluid is in a reservoir that has the same rock structure and comes from the old hydrothermal system. Based on the results of the analysis of fluid characteristics obtained from the research, it can be concluded that the hot springs of the Wawolesea Region are an indicator of the presence of geothermal sources and further research is needed on the magnitude of the geothermal potential.
Paragenesis Prospek Endapan Bijih Besi Daerah Tanjung Kecamatan Bontocani Kabupaten Bone, Sulawesi Selatan Hasbi Bakri; Harwan Harwan; Alam Budiman Thamsi; Irzal Nur; Firdaus F; Andi Fahdli Heriansyah
Jurnal Geomine Vol 9, No 2 (2021): Edisi Agustus 2021
Publisher : Universitas Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33536/jg.v9i2.971

Abstract

Iron ore is the second most abundant metal on earth. The characteristics of this iron ore usually consist of iron ore carrier minerals associated with other minerals. One area that has iron ore prospects is the Tanjung area, Bontocani District, Bone Regency. The purpose of this study was to determine the types of iron ore carrier minerals and their associations, mineralization characteristics and paragenesis of iron ore carrier minerals. The data collection technique is carried out directly in the field by taking random samples in the field according to field conditions. Laboratory analysis uses mineragraphic analysis to determine iron ore carrier minerals and their associated minerals and X-Ray Diffraction analysis to determine iron ore carrier minerals that are not identified by mineragraphic analysis. From the results of the study found iron ore carrier minerals magnetite, goethite and hematite and their associated minerals in the form of sulfide minerals in the form of pyrite, covelite and braunite. The iron ore textures found are replacement and intergrowth textures. Paragenesis of mineral deposits formed successively are magnetite, hematite, pyrite, cuprite, braunite and goethite.
Perbandingan Antara Metode Poligon, Inverse Distance Weighting, Dan Ordinary Kriging Pada Estimasi Sumberdaya Timah Aluvial, Dan Analisis Sebaran Endapannya Muhammad Syahrul Ramadhan; Asran Ilyas; Irzal Nur; Sri Widodo
Jurnal Geomine Vol 9, No 3 (2021): Edisi Desember 2021
Publisher : Universitas Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33536/jg.v9i3.1054

Abstract

Pulau Bangka merupakan satu dari sekian banyak daerah di Indonesia yang memiliki potensi sumberdaya mineral yang cukup banyak. Salah satunya adalah endapan timah. Penyebaran timah di Pulau Bangka merupakan kelanjutan dari Tin Mayor South East Asian Tin Belt. Endapan timah merupakan komoditas utama dalam eksplorasi endapan mineral logam di Pulau Bangka yang membuat Indonesia merupakan salah satu negara penghasil timah terbesar di dunia. Salah satu perusahaan pertambangan bijih timah di Bangka Belitung adalah PT Timah Tbk yang mengeksplorasi dan mengestimasi sumberdaya mineral yang dilanjutkan dengan proses perhitungan cadangan. Penelitian ini bertujuan untuk mengetahui besarnya sumberdaya timah aluvial dan menganalisis sebaran timah aluvial dengan mempertimbangkan genesis endapan timah aluvial pada sungai purba. Pada penelitian ini dilakukan estimasi sumberdaya dengan menggunakan metode poligon, inverse distance weighting, dan ordinary kriging untuk mengetahui metode yang tepat berdasarkan kondisi geologi, genesis endapan, dan mineralisasi dari endapan yang diestimasi. Berdasarkan hasil estimasi dari tiga kategori kelas sumberdaya (terukur, tertunjuk dan tereka) dengan metode poligon didapatkan total sumberdaya endapan timah aluvial sebesar 8732 ton Sn, dengan metode inverse distance weighting sebesar 8627 ton Sn, dan dengan metode ordinary kriging sebesar 8752 ton Sn. Sebaran timah pada lokasi penelitian banyak terkonsentrasi pada bagian punggungan (hulu) sungai purba, semakin jauh dari hulu menunjukkan konsentrasi endapan timah aluvial semakin menurun. Dari hasil analisis besarnya sumberdaya dan sebaran timah aluvial, maka metode estimasi yang paling optimal dilakukan adalah metode ordinary kriging.
Karakteristik Endapan Bijih Besi Daerah Pakke Desa Langi Kecamatan Bontocani Kabupaten Bone Provinsi Sulawesi Harwan Baharuddin; Irzal Nur; Adi Maulana; Nurliah Jafar; Firdaus F; Andi Fahdli Heriansyah
Jurnal Geomine Vol 8, No 3 (2020): Edisi Desember 2020
Publisher : Universitas Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33536/jg.v8i3.631

Abstract

Bijih besi di daerah Pakke ditemukan berupa bongkah-bongkah bijih besi magnetit dan hematit yang berasosiasi dengan intrusi granodiorit dan pegmatit granodiorit (Utoyo, 2008). Penelitian ini bertujuan untuk mengetahui kondisi geologi, jenis batuan dan mineral pembawa bijih besi, serta karakteristik endapan bijih besi daerah penelitian. Tahapan pengambilan data berupa Pengamatan Singkapan. Pengambilan sampel litologi, menggunakan metode Rock Sampling. Metode analisis yang digunakan untuk menentukan karakatersitik endapan bijih besi yaitu analisis petrografi untuk mengetahui jenis litologi, analisis mineragrafi untuk mengetahui mineral pembawa bijih dan analisis XRD (X-Ray Diffraction) untuk mengetahui mineral alterasi dan mineral bijih. Berdasarkan tipe alterasi dan mineralisasi diketahui bahwa tipe endapan bijih besi pada daerah penelitian yaitu endapan skarn. Dimana endapan skarn ini terbentuk proses metamorfisme kontak yang bertemperatur tinggi. Magma yang kaya akan silika menginstrusi batuan sedimen yang kaya akan karbonat seperti batugamping. Jenis batuan pada daerah penelitian yaitu batuan beku berupa basal yang diindikasikan sebagai source rock dan batuan karbonat berupa wackstone yang diindikasikan sebagai host rock atau batuan penyimpan bijih besi dimana mineral pembawa bijih besi yaitu magnetit, hematit dan goetit.
Survei Geolistrik untuk Pengembangan Irigasi Air Tanah di Kelurahan Lamatti Rilau - Sinjai, Sulawesi Selatan Muhammad - Ramli; Sufriadin -; Aryanti V A; Irzal Nur; Meinarni Thamrin; Sri Widodo
JURNAL TEPAT : Teknologi Terapan untuk Pengabdian Masyarakat Vol 1 No 2 (2018): Improving Quality of Life within Society
Publisher : Faculty of Engineering UNHAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1072.889 KB) | DOI: 10.25042/jurnal_tepat.v1i2.34

Abstract

Daerah Lamatti Rilau-Sinjai Utara merupakan daerah dengan bentang alam yang berbukit-bukit. Kondisi bentang alam tersebut menjadi kendala dalam pemenuhan kebutuhan air irigasi pertanian dengan pemanfaatan air permukaan. Oleh karena itu, diperlukan pengembangan air tanah untuk mensuplai kebutuhan air irigasi tersebut sebagai upaya peningkatan produksi. Pengembangan sumber daya air tanah terdiri atas beberapa tahapan, namun hal yang paling mendasar adalah identifikasi keterdapatan air tanah di bawah permukaan. Metode investigasi yang sangat popular adalah pengukuran tahanan jenis batuan. Nilai tahanan jenis batuan merupakan representasi dari variasi karakteristik fisik dan kimia batuan. Oleh karena itu, hubungan antara jenis batuan dan nilai tahanan jenis merupakan dua hal yang menjadi dasar analisis dalam kegiatan ini. Daerah Lamatti Rilau – Sinjai Utara tersusun atas material batuan sedimen Formasi Walanae(Tmpw), Batuan Gunungapi Lompobatang (Qlv) dan Endapan aluvium dan pantai (Qac). Pengamatan lapangan menunjukkan sejumlah singkapan batupasir yang berpotensi sebagai lapisan pembawa air. Nilai tahanan jenis batuan tersebut bervariasi dari 2,0 – 104,0 ohm-m. Variasi nilai tersebut menunjukkan bahwa pada kedalaman tertentu terdapat lapisan pembawa air tanah. Dari 3 titik investigasi geolistrik, titik GL-3 merupakan lokasi yang dapat lakukan pengembangan sumur produksi air tanah dengan kedalaman sumur 100 m.