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GEOLOGI DAN KARAKTERISTIK BIJIH PIT RAMBA JORING DEPOSIT MARTABE, SUMATERA UTARA Arifin, Asri; Rosana, Mega Fatimah; Yuningsih, Euis Tintin; Yoseph, Boy
Buletin Sumber Daya Geologi Vol 14, No 2 (2019): Buletin Sumber Daya Geologi
Publisher : Buletin Sumber Daya Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1743.098 KB)

Deposit Ramba Joring merupakan bagian dari wilayah Kontrak Karya (KK) pertambangan umum PT Agincourt Resources yang terletak di Kelurahan Aek Pining, Kecamatan Batangtoru, Kabupaten Tapanuli Selatan, Provinsi Sumatera Utara. Penelitian ini bertujuan untuk mengetahui kondisi geologi meliputi geomorfologi, stratigrafi dan struktur geologi serta karakteristik bijih yang mengandung emas-perak pada deposit Ramba Joring. Penelitian dilakukan pada 44 lubang bor dan 15 conto permukaan. Penelitian menggunakan metode analisis petrografi sayatan tipis dan poles, Analytical Spectral Devices (ASD), Scanning Electron Microscopy with Energy Dispersive (SEM EDS) serta pengolahan statistik data geokimia assay berupa nilai kadar kandungan Au, Ag, Cu, SxS (sulfide sulphur) yang didapatkan melalui analisis Atomic Absoption Spectrometry (AAS). Daerah penelitian tersusun oleh litologi, diurutkan dari tua ke muda, berupa satuan andesit hornblende dan breksi polimik-monomik. Satuan batuan andesit hornblende dan breksi polimik-monomik teralterasi kuat oleh empat jenis alterasi yaitu, silisifikasi (kuarsa-kalsedon-alunit-kaolinit±dikit), argilik lanjut (alunit±kuarsa-kaolinit±dikit-pirofilit), argilik (ilit±smektit-alunit-kaolinit-kuarsa) dan propilitik (klorit-epidot-kalsit). Terdapat enam jenis mineral sulfida pada daerah penelitian, paragenesa dimulai dari pirit, enargit, tennantit, tetrahedrit dan kovelit bersamaan dengan pengendapan emas-perak serta pirit dengan kristal berbentuk sempurna yang terbentuk paling akhir. Hasil uji pada data assay geokimia menunjukkan adanya korelasi antara kandungan unsur Au, Ag, Cu dan SxS (sulfide sulphur) terhadap jenis alterasi. Diketahui bahwa mineralisasi emas dan logam lainnya berasosiasiasi dengan mineral sulfida yang melimpah pada alterasi silisifikasi namun semakin berkurang pada jenis alterasi argilik hingga menghilang pada alterasi propilitik.

GEOLOGI DAN KARAKTERISTIK BIJIH PIT RAMBA JORING DEPOSIT MARTABE, SUMATERA UTARA Arifin, Asri; Rosana, Mega Fatimah; Yuningsih, Euis Tintin; Yoseph, Boy
Buletin Sumber Daya Geologi Vol. 14 No. 2 (2019): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Deposit Ramba Joring merupakan bagian dari wilayah Kontrak Karya (KK) pertambangan umum PT Agincourt Resources yang terletak di Kelurahan Aek Pining, Kecamatan Batangtoru, Kabupaten Tapanuli Selatan, Provinsi Sumatera Utara. Penelitian ini bertujuan untuk mengetahui kondisi geologi meliputi geomorfologi, stratigrafi dan struktur geologi serta karakteristik bijih yang mengandung emas-perak pada deposit Ramba Joring. Penelitian dilakukan pada 44 lubang bor dan 15 conto permukaan. Penelitian menggunakan metode analisis petrografi sayatan tipis dan poles, Analytical Spectral Devices (ASD), Scanning Electron Microscopy with Energy Dispersive (SEM EDS) serta pengolahan statistik data geokimia assay berupa nilai kadar kandungan Au, Ag, Cu, SxS (sulfide sulphur) yang didapatkan melalui analisis Atomic Absoption Spectrometry (AAS). Daerah penelitian tersusun oleh litologi, diurutkan dari tua ke muda, berupa satuan andesit hornblende dan breksi polimik-monomik. Satuan batuan andesit hornblende dan breksi polimik-monomik teralterasi kuat oleh empat jenis alterasi yaitu, silisifikasi (kuarsa-kalsedon-alunit-kaolinitÂ±dikit), argilik lanjut (alunitÂ±kuarsa-kaolinitÂ±dikit-pirofilit), argilik (ilitÂ±smektit-alunit-kaolinit-kuarsa) dan propilitik (klorit-epidot-kalsit). Terdapat enam jenis mineral sulfida pada daerah penelitian, paragenesa dimulai dari pirit, enargit, tennantit, tetrahedrit dan kovelit bersamaan dengan pengendapan emas-perak serta pirit dengan kristal berbentuk sempurna yang terbentuk paling akhir. Hasil uji pada data assay geokimia menunjukkan adanya korelasi antara kandungan unsur Au, Ag, Cu dan SxS (sulfide sulphur) terhadap jenis alterasi. Diketahui bahwa mineralisasi emas dan logam lainnya berasosiasiasi dengan mineral sulfida yang melimpah pada alterasi silisifikasi namun semakin berkurang pada jenis alterasi argilik hingga menghilang pada alterasi propilitik.

Vertical Electrical Sounding Exploration of Groundwater in Kertajati, Majalengka, West Java, Indonesia Nugraha, Gumilar Utamas; CSSSA, Boy Yoseph; Nur, Andi Agus; Pranantya, Pulung Arya; Handayani, Lina; Lubis, Rachmat Fajar; Bakti, Hendra
Indonesian Journal on Geoscience Vol 8, No 3 (2021)
Publisher : Geological Agency

Continuously increasing population and progressive infrastructural development in the region of Kertajati International Airport, Indonesia, emphasize the need to develop a sustainable water supply network. Airport facilities require sufficient water resources, which can be obtained from surface water and groundwater. Groundwater exploration can provide necessary information for assessing water resources. The purpose of this study is to analyze the configuration of aquifers in the studied area. A Schlumberger array was used to carry out twelve vertical electrical soundings (VES) with AB/2 electrode spacing ranging from 1.5 m to 150 m. IPI2win software was used to qualitatively interpret the VES results and it suggested the presence of three distinct lithological units interpreted as clay, alluvial sand, and a Lower Quaternary formation. In general, resistivity values in the studied area can be divided into five resistivity categories: very low resistivity with values ranging from 1 Î©m to 10 Î©m, low resistivity with values ranging from 10 Î©m to 50 Î©m, medium resistivity with values ranging from 50 Î©m to 100 Î©m, high resistivity with values ranging from 100 Î©m to 200 Î©m, and very high resistivity with values > 200 Î©m. The geo-electric interpretation revealed three geo-electric layers: topsoil (1 - 144 â„¦ m), sand (1 - 298 â„¦ m), and clay (1 - 82 â„¦ m). Aquifers in the studied area are lithologically composed of sand. Clay is the dominant lithology in the studied area, so the presence of aquifers in this area is very limited, and thus the supply of groundwater is also limited. The exploitation of groundwater must be limited and controlled to maintain the sustainability of groundwater in the studied area.

Vertical Electrical Sounding Exploration of Groundwater in Kertajati, Majalengka, West Java, Indonesia Nugraha, Gumilar Utamas; CSSSA, Boy Yoseph; Nur, Andi Agus; Pranantya, Pulung Arya; Handayani, Lina; Lubis, Rachmat Fajar; Bakti, Hendra
Indonesian Journal on Geoscience Vol 8, No 3 (2021): in-press
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.8.3.359-369

Continuously increasing population and progressive infrastructural development in the region of Kertajati International Airport, Indonesia, emphasize the need to develop a sustainable water supply network. Airport facilities require sufficient water resources, which can be obtained from surface water and groundwater. Groundwater exploration can provide necessary information for assessing water resources. The purpose of this study is to analyze the configuration of aquifers in the studied area. A Schlumberger array was used to carry out twelve vertical electrical soundings (VES) with AB/2 electrode spacing ranging from 1.5 m to 150 m. IPI2win software was used to qualitatively interpret the VES results and it suggested the presence of three distinct lithological units interpreted as clay, alluvial sand, and a Lower Quaternary formation. In general, resistivity values in the studied area can be divided into five resistivity categories: very low resistivity with values ranging from 1 Î©m to 10 Î©m, low resistivity with values ranging from 10 Î©m to 50 Î©m, medium resistivity with values ranging from 50 Î©m to 100 Î©m, high resistivity with values ranging from 100 Î©m to 200 Î©m, and very high resistivity with values > 200 Î©m. The geo-electric interpretation revealed three geo-electric layers: topsoil (1 - 144 â„¦ m), sand (1 - 298 â„¦ m), and clay (1 - 82 â„¦ m). Aquifers in the studied area are lithologically composed of sand. Clay is the dominant lithology in the studied area, so the presence of aquifers in this area is very limited, and thus the supply of groundwater is also limited. The exploitation of groundwater must be limited and controlled to maintain the sustainability of groundwater in the studied area.

KARAKTERISTIK FLUIDA PEMBAWA MINERALISASI PIT RAMBA JORING DEPOSIT MARTABE, SUMATRA UTARA: MINERALIZATION BEARING FLUID CHARACTERISTIC OF RAMBA JORING PIT MARTABE DEPOSIT, NORTH SUMATRA Arifin, Asri; Rosana, Mega Fatimah; Yuningsih, Euis Tintin; Yoseph CSSSA, Boy
Buletin Sumber Daya Geologi Vol. 16 No. 2 (2021): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47599/bsdg.v16i2.314

The research aims to determine hydrothermal evolution of the mineralisation bearing fluid contained in the Ramba Joring Pit, including temperature, pressure, density and depth of mineralisation deposition formation. This research uses the fluid inclusion analysis. Inclusion sampling was carried out on two main textures of ore namely vuggy silica texture formed at range Th 331ÂºC to 394ÂºC, Tm -15.19ÂºC to -12.94ÂºC with salinity of 14.42 wt% - 14.89 wt%. NaCl equivalent and brecciated texture formed at range Th 287.8ÂºC â€“ 398.2ÂºC, Tm -14.89ÂºC to -11,76ÂºC and salinity 13.91 wt% â€“ 14.87 wt%. NaCl equivalent. The positive correlation between the homogenization temperature of mineralization formation and salinity of the solution indicates that the leaching process that forms cavities in rocks occurs at the initial stage of the hydrothermal alteration process that begins with the leaching process forming cavities (silica vuggy) followed by the process of silicification with brecciated texture, the deposition of mineralization takes place at this stage. The origin of the solution forms a hydrothermal deposition is a type of basinal water-seawater solution in the form of connate water which is still influenced by surface water/meteoric water, also shows an indication of a relationship with magmatic water. The density of metal-forming fluids ranges from 0.8 gr/cm3 â€“ 0.9 gr/cm3 while the process that takes place in the formation of ore in Ramba Joring Pit is isothermal mixing with a slight warming effect/boiling.

Identifikasi Zona Infiltrasi Airtanah di Kawasan Karst Berdsarkan Nilai Tekanan Parsial CO2 dan Indeks Kejenuhan CaCO3 (SIc) di Sekitar Perbukitan Karst Watuputih Nofi Muhammad Alfan Asghaf; Boy Yoseph CSSS Alam; Hendarmawan Hendarmawan
Jurnal Lingkungan dan Bencana Geologi Vol 10, No 2 (2019)
Publisher : Badan Geologi

Persebaran mata air di sekitar perbukitan karst Watuputih menunjukkan kawasan tersebut memiliki potensi air tanah yang tinggi. Kehadiran mata air karst tersebut sebagai akibat dari kondisi geologi yang didominasi oleh batuan karbonat yang mudah larut dan struktur geologi yang intensif. Penelitian ini bertujuan untuk mengetahui karakteristik daerah infiltrasi air tanah berdasarkan analisis tekanan parsial CO2 (Pco2) dan indeks kejenuhan CaCO3 (SIc), dikombinasikan dengan analisis fasies kimia air tanah dan kelurusan morfologi. Hasil analisis menunjukkan, pada densitas kelurusan morfologi tinggi memiliki nilai Pco2 rendah dan air tanah dalam kondisi jenuh sedangkan pada densitas kelurusan morfologi rendah nilai Pco2 tinggi dan air tanah dalam kondisi jenuh hingga tidak jenuh. Korelasi Pco2 dengan SIc dikombinasikan dengan kondisi geologi dan fasies kimia air tanah menghasilkan tiga tipe mata air, yaitu (1) Nilai Pco2 tinggi, nilai SIc jenuh hingga tidak jenuh, fasies hidrokimia dominan Ca-Mg-HCO3, densitas morfologi rendah, lapisan soil tebal, dan media aliran air tanah dominan jaringan pori memiliki infiltrasi rendah; (2) Nilai Pco2 rendah, nilai SIc jenuh, fasies hidrokimia dominan Ca-HCO3, densitas morfologi tinggi, lapisan tanah tipis, dan media aliran air tanah dominan jaringan pori dan rekahan batuan yang rapat, tetapi mulai berkembang jaringan rongga, memiliki infiltrasi tinggi; dan (3) Nilai Pco2 sangat tinggi, nilai SIc tidak jenuh, fasies hidrokimia Ca-Na-HCO3 dan Ca-Mg-Cl-HCO3, densitas morfologi tinggi, lapisan soil tebal, media aliran air tanah jaringan pori, dan litologi batuan nonkarbonatan, memiliki infiltrasi rendah.

PERAN SESAR TERHADAP KARAKTER DAN ARAH ALIRAN AIRTANAH PADA ENDAPAN VOLKANIK DI LERENG TENGGARA G. GEDE, KABUPATEN CIANJUR, JAWABARAT Ismawan T. -; Yudi Rahayudin -; Boy Yoseph CSSSA -; Bombom Rahmat Suganda -; Nursiyam Barkah -
Bulletin of Scientific Contribution: GEOLOGY Vol 11, No 1 (2013): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Volcano as high morphology feature acts as a good water catchment and recharge area. This area also has a volcanic deposition characteristic that changes within a near range, and usually has complex geological structures that effects the groundwater systems. The aim of this study is to identity the role of faults toward groundwater conditions, determine facies and shallow groundwater flow based on the water table. The study area is in a volcanic deposition aquifer system that is composed of lapilli tuff, volcanic breccias, and sand. The occurance of several springs with groundwater conditions are controlled by faults and fractures. Physical characteristics of the water comprises, EC=104μS/cm -490 μS/cm, TDS = 49 mg/L- 240 mg/L, pH 4,2 – 8,6, Temperature 20,4°C – 26°C, debit 0,05 L/sec up to 100 L/sec. Chemical facies of the water is divided into three types: Ca, HCO3, Ca, Mg HCO3 and Mg, Ca HCO3.The direction of the shallow groundwater flow generally follows the topographics features with a direction northwest-southeast.

KENDALI GEOLOGI TERHADAP POLA ALIRAN AIRTANAH BEBAS DAN TERKEKANG DALAM EVALUASI POTENSI AKIFER, STUDI KASUS DAERAH PANDAAN DAN SEKITARNYA, KABUPATEN PASURUAN, JAWA TIMUR Teuku Reza; . Hendarmawan; Boy Yoseph Cahya Sunan Sakti Syah Alam
Bulletin of Scientific Contribution: GEOLOGY Vol 18, No 1 (2020): Bulletin of Scientific Contribution : GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Geological control has been examined on the pattern of groundwater flow from free and confined aquifer in the evaluation of aquifer potency in case study in the Pandaan and surrounding areas, Pasuruan Regency, East Java. Groundwater elevation (MAT) measurement data of dug wells, borehole pumping tests, 1D geoelectricity, and wellbore log results indicate that groundwater flow patterns from free and confined aquifers have the same flow direction from southwest to northeast indicating that the distribution hydrogeological units of both aquifers are relatively homogeneous. The depths of the free aquifer from 1 to 6 meters with sand and tuffaceous sand lithology. Confined aquifer from a depth of 40 meters with a thickness between 20 to 70 meters. The aquifer unit is a tuff breccias rock from the Mt. Arjuna Welirang and Tuf Rabano Formation, aquiclude units in the form of andesite lava from Mt. Arjuna Welirang. Potential confined aquifer evaluated from pumping test has a transmissivity value between 54 - 315 m2 / day. Hydraulic conductivity (k) values are between 1.46 - 12.4 m / day. Keywords: Hydrogeological unit, transmissivity, hydraulic conductivity, aquifer, aquiclude

OPTIMALISASI PEMANFAATAN SISTEM AGROFORESTRI SEBAGAI BENTUK ADAPTASI DAN MITIGASI TANAH LONGSOR Pradnya Raditya Rendra; Nana Sulaksana; Boy Yoseph C.S.S.S. Alam
Bulletin of Scientific Contribution: GEOLOGY Vol 14, No 2 (2016): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Landslide is a natural disaster that often occur in Indonesia and cause a significant impact. Landslide may occur due to static factor (slope) and dynamic factor (land use). Landslide mitigation can be done to prevent the negative impact of landslide. Landslide mitigation through slope stabilization can be done with vegetative technique. Vegetative technique as a landslide mitigation with sustainable land production is also known as agroforestry. Agroforestry is a land use systems made by various technologies through the utilization of annual crops, perennial crops, and/or livestock , either alternately or at the same time in a certain period to form ecological, social, and economic interactions. Agroforestry system has more advantages than other land use systems. One of the advantage of this system is can be used on steep slope area. Multistory agroforestry system can prevent landslide by forming soil organic material, improving soil structure, and making soil more stable. Utilization of multistory agroforestry system with various types of storied canopy trees considered as appropiate landslide mitigation because the closure of canopy tress are tightly and stratified, their root system is excellent, and the soil cover such as grasses and shrubs is important to prevent landslide. Furthermore, agroforestry system can also be used to produce food crops, fodder, honey, building materials, and medicinal materials. Keyword : Agroforestry, mitigation, slope, landslide. Tanah longsor merupakan bencana alam yang sering terjadi di Indonesia dan menimbulkan dampak cukup besar. Tanah longsor dapat terjadi akibat faktor statis (kemiringan lereng) dan faktor dinamis (tata guna lahan). Mitigasi tanah longsor dilakukan untuk mencegah dampak negatif tanah longsor. Mitigasi tanah longsor melalui stabilisasi lereng dapat dilakukan dengan rekayasa vegetatif. Rekayasa vegetatif sebagai mitigasi tanah longsor dengan produksi lahan berkelanjutan tersebut disebut juga sebagai sistem agroforestri. Agroforestri merupakan sistem penggunaan lahan yang dilakukan dengan berbagai teknologi melalui pemanfaatan tanaman semusim, tanaman tahunan, dan/atau ternak dalam waktu bersamaan atau bergiliran pada periode tertentu sehingga terbentuk interaksi ekologi, sosial, dan ekonomi. Sistem agroforestri memiliki lebih banyak kelebihan dibandingkan sistem penggunaan lahan lain. Salah satu kelebihan sistem ini adalah dapat digunakan pada lahan berlereng curam. Sistem agroforestri multistrata dapat mencegah tanah longsor dengan membentuk bahan organik tanah, memperbaiki struktur tanah, dan membuat tanah menjadi lebih stabil. Pemanfaatan sistem agroforestri multistrata dengan berbagai jenis tanaman tajuk bertingkat dinilai sebagai langkah tepat mitigasi tanah longsor karena adanya penutupan tajuk pepohonan yang rapat dan bertingkat, sistem perakaran yang sangat baik, serta penutup tanah berupa rerumputan dan semak belukar yang sangat penting untuk menghindari tanah longsor. Selain itu, sistem agroforestri juga dapat dimanfaatkan sebagai penghasil bahan pangan, pakan ternak, madu, bahan bangunan, dan bahan obat. Kata kunci :Agroforestri, mitigasi, lereng, longsor.

KONDISI GEOLOGI TEKNIK PASIR LEPAS TERHADAP PERENCANAAN DAN PRE-DESAIN BENDUNGAN TIPE URUGAN (EARTH DAM) DI DESA KANDANG AMPEK, KABUPATEN PARIAMAN, SUMATERA BARAT Boy Yoseph -
Bulletin of Scientific Contribution: GEOLOGY Vol 5, No 2 (2007): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

The Observatory area include in the fisiography of Rangkaian Pegunungan Barisan Barat, which is located at the elevation +604 m until +620 m above the sea level. Geologically is consist of two unit geomorphology, i.e geomorphology unit of breccia volcanic hilly extremely steep and geomorphology unit of breccia tuff hilly slope. These geomorphology condition in caused the hydraulic gradient quite high and so the speed of current surface water too. Litology of the observatory area is breccia volcanic. The geology structure of the observatory area which is holding a role is not found, but there are joints in several locations. Which were assumsed come from the tectonic activity which developed along the Sumatera Fault (Semangko Fault).Based on soil mecanic datas, the dam material has a relative session = 0 . Where as the (C) valve (cohessi) is very small, because of that the soil bearing capacity is very small, and its necessary to make a foundation. One of many years to increase Dr (relative session) from those material to mix soil (soil mixing) (to add the component cohesive /silt and clay). The Observatory area included to the earthquake area, so type of dam is earth dam. clay core on dam body is required to decrease the seepage. Dam body is consisted with the comparation of soil mix 9:1:0 and 8:1:1.

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