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Multistage Gold Mineralization at The Wanagon Gold Prospect, Ertsberg District, Mimika Regency, Papua Province, Indonesia Endang Hartiningsih; Syafrizal Syafrizal; IGB Eddy Sucipta; Sudarto Notosiswoyo
Indonesian Journal on Geoscience Vol 9, No 3 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.3.279-290

DOI:10.17014/ijog.9.3.279-290The Wanagon Gold prospect area located in the Ertsberg District, Papua Province, the eastern part of Indonesia, is predominantly underlain by Upper Mesozoic to Cenozoic sedimentary rocks intruded by the Wanagon Sill monzodiorite-diorite and andesite intrusion (Wanagon Dike). The study by previous researchers at Wanagon Gold prospect was based on pre-2005 exploration data and did not contain extensive additional drillings in 2007-2011. This paper aims to elucidate the genesis of the Wanagon Gold deposits based on the latest exploration data. The mineralogy was determined by using thin section and polish section analyses, a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), and Near-Infrared spectroscopy (NIR). The chemical composition of the rock was identified using an X-ray fluorescence spectrometer (XRF). Gold mineralization is associated with pyrite, of which there are three types of gold-bearing pyrite: (1) massive pyrite, (2) disseminated pyrite, and (3) fine-grained pyrite associated with clay minerals. Only massive pyrite contains visible gold-bearing minerals such as native gold, electrum, and gold-telluride minerals, while in nonmassive pyrite, gold is only detected by the assay. The deposit is interpreted as structurally controlled distal gold skarn. Instead, its local association of gold with arsenic also indicates a minor component of more-distal sediment-hosted type gold mineralization.

Multistage Gold Mineralization at The Wanagon Gold Prospect, Ertsberg District, Mimika Regency, Papua Province, Indonesia Endang Hartiningsih; Syafrizal Syafrizal; IGB Eddy Sucipta; Sudarto Notosiswoyo
Indonesian Journal on Geoscience Vol. 9 No. 3 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.3.279-290

DOI:10.17014/ijog.9.3.279-290The Wanagon Gold prospect area located in the Ertsberg District, Papua Province, the eastern part of Indonesia, is predominantly underlain by Upper Mesozoic to Cenozoic sedimentary rocks intruded by the Wanagon Sill monzodiorite-diorite and andesite intrusion (Wanagon Dike). The study by previous researchers at Wanagon Gold prospect was based on pre-2005 exploration data and did not contain extensive additional drillings in 2007-2011. This paper aims to elucidate the genesis of the Wanagon Gold deposits based on the latest exploration data. The mineralogy was determined by using thin section and polish section analyses, a scanning electron microscope with an energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), and Near-Infrared spectroscopy (NIR). The chemical composition of the rock was identified using an X-ray fluorescence spectrometer (XRF). Gold mineralization is associated with pyrite, of which there are three types of gold-bearing pyrite: (1) massive pyrite, (2) disseminated pyrite, and (3) fine-grained pyrite associated with clay minerals. Only massive pyrite contains visible gold-bearing minerals such as native gold, electrum, and gold-telluride minerals, while in nonmassive pyrite, gold is only detected by the assay. The deposit is interpreted as structurally controlled distal gold skarn. Instead, its local association of gold with arsenic also indicates a minor component of more-distal sediment-hosted type gold mineralization.

Characterizing SO2 Emission Rate, Thermal Anomalies, from Opened and Closed Vent System at Agung, Bromo, and Sinabung Volcanoes in Indonesia Hilma Alfianti; Asep Saepuloh; Mamay Surmayadi; Syegi L. Kunrat; Ugan B. Saing; I.G.B. Eddy Sucipta; Sofyan Primulyana
Indonesian Journal on Geoscience Vol. 10 No. 2 (2023)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.10.2.277-295

Agung, Bromo, and Sinabung Volcanoes have high volcanic activity over the last decade, and have different eruption characteristics. Hence, it would be fascinating to study the characteristics of their volcanic activity patterns based on SO2 emission rates and thermal anomaly correlated with the seismicity data. The SO2 emission rate measurement was carried out using the Differential Optical Absorption Spectroscopy (DOAS), and calculated based on SO 2 column density, distance of measurement, wind speed, and wind direction. In addition, SO2 emission was detected using Ozone Monitoring Instrument (OMI) images with daily global coverage. Thermal anomaly detection was performed using Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) of Thermal Infrared (TIR) subsystem with high spatial resolution (90x90 m). ASTER TIR images were corrected for radiometric and thermal atmospheric. The emissivity and brightness temperature separation algorithm was applied to obtain surface temperature of Agung, Bromo, and Sinabung Volcanoes. All the data were correlated with the seismicity of each volcano. The SO2 emission rates correlate with the magma ascent to the shallow depth in an open system volcano (Bromo Volcano). In the closed-system volcanoes (early phase of Agung and Sinabung), SO2 emission was detected after the transition of closed to open system. Magmatic injection from the reservoir to the shallow depth was detected as thermal anomalies, such as in Agung Volcano. Whereas in Bromo Volcano, the thermal anomaly was insignificant since Bromo Volcano has an explosive eruption at a short period, so the ASTER image could not observe the thermal anomaly on the eruption time. Thermal anomaly pattern in Sinabung Volcano was the manifestation of new magmatic injection to the shallow depth. Therefore, their increase serves as indicators for the increasing magmatic activity prior to the eruptions. Keywords: SO2 emission rate, thermal anomaly, DOAS, OMI, ASTER, Open Vent, Closed Vent

Rock Mineralogy Analysis of Airbenakat Formation to Map the Characteristics of the Reservoir Rocks in each Depositional Environment Kharisma Idea; Taufan Marhaendrajana; I GB Eddy Sucipta; Sri Feni
Journal of Petroleum and Geothermal Technology Vol 4, No 2 (2023): November
Publisher : Universitas Pembangunan Nasional "Veteran" Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31315/jpgt.v4i2.10793

The Airbenakat Formation is a sandstone reservoir which is one of the oil reservoirs located in Sumatra and is part of the South Sumatra Basin. The mineral composition of the sandstone reservoir in the Airbenakat Formation consists of quartz minerals as rock grains, clay as matrix and is often identified as cement, while carbonate as rock cement. Based on lithofacies observations, the depositional environment of the Airbenakat Formation consists of: Volcanic Alluvial Fan, Lake, Braid Bar, Braided Channel, Braid Deltaic Environment, Mud Flat, Tidal Sand Bar, Tidal Environment, Shallow Sea, and Deep Sea. This research was conducted on 2 (two) oil fields, namely MRP dan TPN which have different depositional environments but are included in the Airbenakat Formation as part of the South Sumatra Basin.The analyzes used in this study include X-Ray Diffraction (XRD) analysis, petrography, and Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM/EDX). Analysis of the mineralogical content of the Airbenakat Formation will assist to determine the performance of chemical injections such as injection of anionic surfactant. The anionic surfactant used for chemical injection in Airbenakat Formations will be optimal if the content of smectite and calcite minerals can be ascertained. The presence of smectite and calcite minerals will affect the results of anionic surfactant injection. This research shows the results of anionic surfactant injection on the presence of smectite and carbonate in the injected core.

BATUPASIR â€œBULUKUNINGâ€ PADA LEMPUNG BERSISIK DI DAERAH BANJARNEGARA, JAWA TENGAH ; STUDI PETROLOGI, PROVENAN DAN IMPLIKASI TEKTONIK Harsolumakso, Agus Handoyo; Puswanto, Eko; Sucipta, IGB Eddy
Bulletin of Geology Vol 3 No 2 (2019): Bulletin of Geology
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2019.3.2.1

Sandstone unit in the Bulukuning area, Banjarnegara known and even once proposed as the Bulukuning Formation were formerly referred to as the greywacke sandstones as part of the Luk Ulo Melange Complex which is believed as Early Cretaceous-Paleocene in age. The sandstones are lightly metamorphosed and observed in many places to be inclunded in the exotic blocks within the scaly clay which is generally considered as matrix of melange. This study examines the details of lithological characteristics, their provenances and tectonic implications. Undeformed sequences of the Bulukuning Sandstones represented by well bedded sandstones and siltstones. Determinations of fossil species and association of these sandstones yield Paleo-Nummulites and nanno fossil matrices which strongly suggest Middle-Late Eocene (NP15-16). The highly deformed sequence of Bulukuning Sandstones often show block in matrix characters while others develop more boudinage structures as a result of rigid deformation. Analysis of the scaly clay matrix using the illite crystallinity (IC) value suggested that the deformation controlled the formation of scaly clay and boudinage structures occurred at temperatures around 205.916o - 223.014oC (Â± 30Â°). The provenance study of the sandstones confirms that these are resulted from recycled orogens related to the Micro-Continent collision of East Java with the southeast margin of the Sundaland during the Late Eocene-Early Oligocene period. The collision was subsequently followed by the exhumation of Karangsambung accretion complex, previously formed volcanic rocks and several Sundanese land blocks.

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