scholarly journals Geology and Geothermal Setting of Tompaso Geothermal System, Indonesia, with Comparisons of Andesite Alteration Patterns with Wairakei, New Zealand

2021 ◽  
Author(s):  
◽  
Kartika Palupi Savitri
Keyword(s):  
Hydrothermal Alteration ◽  
Short Wave ◽  
Age Dating ◽  
Core Material ◽  
Geothermal System ◽  
Scattered Electron ◽  
Subsurface Geology ◽  
North Sulawesi ◽  
Alteration Processes ◽  
First Time

<p>Tompaso geothermal system is a typical volcanic arc geothermal system in North Sulawesi, Indonesia. Although situated close to the Tondano caldera, subsurface lithologies and structures do not show any evidence for caldera-related features and the system is inferred to be related to the andesitic Soputan volcano. The subsurface geology of Tompaso consists of Tuff B unit, Rhyolite unit, Andesite B unit, Pitchstone unit, Pyroclastic Breccia unit,Andesite A unit, Pumice unit, and Tuff A unit, respectively, from the oldest penetrated unit. The silicic Pitchstone and Rhyolite units are presumed to be sourced from the same magma chamber. Petrological and mineralogical observations using binocular and petrographic microscopy, short-wave infrared (SWIR) analysis, and back-scattered electron (BSE) imaging combined with energy dispersive X-ray spectroscopy (EDS) have been applied to cuttings and limited core material from three boreholes: LHD-26, LHD-27, and LHD-32. Age dating has not been undertaken and, thus, conclusions on correlations between subsurface geology inferred here with surface formation groupings from previous works cannot be drawn.  Tompaso geothermal system is characterised primarily by variations in the fracturing within the reservoir. Secondary mineralogy and the structure of present-day temperature of the system suggest that the movement of hydrothermal fluids at Tompaso is controlled by faults: the Soputan, Tempang, and A-A’ faults, the last defined for the first time in this thesis. Soputan Fault controls the outflow of the system. On the other hand, the influence of Tempang and A-A’ faults is dominant only in the upper portion of the system. The A-A’ fault likely acts as a channel for cooler meteoric surface water, while the Tempang Fault is inferred to have experienced self-sealing and appears to be an impermeable structure in the system. The self-sealing process of the Tempang Fault and/or the introduction of meteoric water through the A-A’ fault may be related to the cooling of the northern and western part of the system.  The challenges in identifying protoliths in active geothermal areas is addressed here through studies of the influence of andesite textures on the preferences of hydrothermal alteration processes. Wairakei andesites were chosen for comparison to Tompaso andesites, especially because of its different geological setting and geothermal reservoir structure. The results suggest that mineral composition and arrangement affect the preference of hydrothermal alteration on andesites.</p>

scholarly journals Geology and Geothermal Setting of Tompaso Geothermal System, Indonesia, with Comparisons of Andesite Alteration Patterns with Wairakei, New Zealand

2021 ◽  
Author(s):  
◽  
Kartika Palupi Savitri
Keyword(s):  
Hydrothermal Alteration ◽  
Short Wave ◽  
Age Dating ◽  
Core Material ◽  
Geothermal System ◽  
Scattered Electron ◽  
Subsurface Geology ◽  
North Sulawesi ◽  
Alteration Processes ◽  
First Time

<p>Tompaso geothermal system is a typical volcanic arc geothermal system in North Sulawesi, Indonesia. Although situated close to the Tondano caldera, subsurface lithologies and structures do not show any evidence for caldera-related features and the system is inferred to be related to the andesitic Soputan volcano. The subsurface geology of Tompaso consists of Tuff B unit, Rhyolite unit, Andesite B unit, Pitchstone unit, Pyroclastic Breccia unit,Andesite A unit, Pumice unit, and Tuff A unit, respectively, from the oldest penetrated unit. The silicic Pitchstone and Rhyolite units are presumed to be sourced from the same magma chamber. Petrological and mineralogical observations using binocular and petrographic microscopy, short-wave infrared (SWIR) analysis, and back-scattered electron (BSE) imaging combined with energy dispersive X-ray spectroscopy (EDS) have been applied to cuttings and limited core material from three boreholes: LHD-26, LHD-27, and LHD-32. Age dating has not been undertaken and, thus, conclusions on correlations between subsurface geology inferred here with surface formation groupings from previous works cannot be drawn.  Tompaso geothermal system is characterised primarily by variations in the fracturing within the reservoir. Secondary mineralogy and the structure of present-day temperature of the system suggest that the movement of hydrothermal fluids at Tompaso is controlled by faults: the Soputan, Tempang, and A-A’ faults, the last defined for the first time in this thesis. Soputan Fault controls the outflow of the system. On the other hand, the influence of Tempang and A-A’ faults is dominant only in the upper portion of the system. The A-A’ fault likely acts as a channel for cooler meteoric surface water, while the Tempang Fault is inferred to have experienced self-sealing and appears to be an impermeable structure in the system. The self-sealing process of the Tempang Fault and/or the introduction of meteoric water through the A-A’ fault may be related to the cooling of the northern and western part of the system.  The challenges in identifying protoliths in active geothermal areas is addressed here through studies of the influence of andesite textures on the preferences of hydrothermal alteration processes. Wairakei andesites were chosen for comparison to Tompaso andesites, especially because of its different geological setting and geothermal reservoir structure. The results suggest that mineral composition and arrangement affect the preference of hydrothermal alteration on andesites.</p>

scholarly journals Subsurface Geology and Hydrothermal Alteration of The Patuha Geothermal Field, West Java: A Progress Report

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter Pratistha Utama
Keyword(s):  
Hydrothermal Alteration ◽  
Geothermal Field ◽  
Rock Properties ◽  
Primary Data ◽  
Geothermal System ◽  
West Java ◽  
Geothermal Exploration ◽  
Subsurface Geology ◽  
Geothermal Fields ◽  
Installed Capacity

Patuha geothermal field is one of the geothermal fields in West Java.  Developed by PT Geo Dipa Energi (Persero) since 2014, the geothermal field produced electricity, with installed capacity amounted to 55 MWe. Patuha geothermal system is vapour-dominated system. The geothermal manifestations are located at approximately 2,100 m asl. The Patuha field consists of three main upflow zones, namely Kawah Putih, Kawah Ciwidey, and Kawah Cibuni. This study analyzed the drill cuttings from 3 wells as the primary data with total depths ranging from 1,581 to 2,166 m with the well’s highest stable temperatures measured of ±230°C. The three wells selected for this research—PPL 02, PPL 04, and PPL 07—were analyzed to describe the rock properties and estimate the prospect areas of present-day geothermal exploration in Patuha. The objective of this paper is to develop a better understanding of the subsurface geology and its correlation to the dynamic processes (i.e., hydrothermal alteration) in Patuha geothermal field. The hydrothermal minerals are formed by near-neutral pH fluids and are characterized by quartz, calcite, clays (smectite, illite, chlorite), wairakite, epidote, and actinolite. The existence of acidic fluids is evident by the formation of acidic hydrothermal minerals e.g., anhydrite at various depth of the studied wells, particularly at PPL 07 which is located around Sugihmukti-Urug area. Moreover, the previous studies by Reyes (1990), Layman and Soemarinda (2003), Rachmawati et al. (2016), Elfina (2017) on hydrothermal minerals, geothermal manifestation characteristics, fluid geochemistry, and conceptual model are adapted to improve the analysis and interpretation of this paper.

Hydrothermal alteration in the Reykjanes geothermal system: Insights from Iceland deep drilling program well RN-17

2010 ◽  
Vol 189 (1-2) ◽  
pp. 172-190 ◽  
Author(s):  
Naomi Marks ◽  
Peter Schiffman ◽  
Robert A. Zierenberg ◽  
Hjalti Franzson ◽  
Gudmundur Ó. Fridleifsson
Keyword(s):  
Hydrothermal Alteration ◽  
Geothermal System ◽  
Deep Drilling

Combining ammonium mapping and short-wave infrared (SWIR) reflectance spectroscopy to constrain a model of hydrothermal alteration for the Acoculco geothermal zone, Eastern Mexico

Geothermics ◽  
2015 ◽  
Vol 53 ◽  
pp. 154-165 ◽  
Author(s):  
Carles Canet ◽  
Berenice Hernández-Cruz ◽  
Abigail Jiménez-Franco ◽  
Teresa Pi ◽  
Berenice Peláez ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Short Wave ◽  
Reflectance Spectroscopy ◽  
Short Wave Infrared

scholarly journals Applying spectral analysis for identification of alteration zones in north Saveh area, Iran

2020 ◽  
Author(s):  
Kazem Rangzan ◽  
Somayeh Beyranvand ◽  
Hoshang Pourkaseb ◽  
Hojjatollah Ranjbar ◽  
Alireza Zarasvandi
Keyword(s):  
Hydrothermal Alteration ◽  
Near Infrared ◽  
Thermal Emission ◽  
Spectral Response ◽  
Volcanic Rocks ◽  
Short Wave ◽  
Rapid Identification ◽  
Spectral Angle Mapper ◽  
Alteration Zones ◽  
The North

An extensive series of volcanic rocks are exposed in the north of Saveh city, Iran, which consist of phyllic, argillic and propylitic hydrothermal alteration types. For the purpose of the investigation, a FieldSpec3® spectroradiometer was used to measure the spectral response of the mineral content of these rocks. The spectral analyses of reflectance curve by The Spectral Geologist (TSG) software could discriminate kaolinite and montmorillonite (argillic), illite, muscovite, phengite and paragonite (phyllic), hornblende and chlorite, siderite (propylitic), hematite and goethite from the gossans. It also detected gypsum of hydrothermal alteration zones. The Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) image, which was used for mapping the hydrothermal alteration minerals, contains the Visible and Near Infrared (VNIR) wavelengths between 0.52 µm and 0.86 µm, Short Wave Infrared (SWIR) wavelengths between 1.6 µm and 2.43 µm and Thermal Infrared (TIR) wavelengths between 8.125 µm and 11.65 µm with 15, 30 and 90 m spatial resolutions, respectively. For calibration of the ASTER images, the extracted spectra of different rocks and minerals were used for atmospheric and radiometric corrections. Mixture tuned matched filtering (MTMF) and Spectral Angle Mapper (SAM) were applied on ASTER data to map the hydrothermal alteration of minerals. The use of the spectroradiometry techniques in conjunction with other data exhibits the ability of these new methods for non-destructive and rapid identification of mineral types for more detailed investigation. The results show that the area has undergone different levels of hydrothermal alteration, so much so that phyllic, argillic and propylitic types of hydrothermal alteration are present in the study area. This may point to high potential and promising zones for the exploration of porphyry mineralisation.

scholarly journals Four Flavan-3-ol Compounds From The Stembark of Chisocheton balansae C.DC. (MELIACEAE)

Molekul ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 9
Author(s):  
Unang Supratman ◽  
Mohamad Fajar ◽  
Supriatno Salam ◽  
Rani Maharani ◽  
Desi Harneti ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
13C Nmr ◽  
Chemical Structure ◽  
Ethyl Acetate Extract ◽  
2D Nmr ◽  
Stem Bark ◽  
Spectroscopic Methods ◽  
Endemic Plants ◽  
North Sulawesi ◽  
First Time

Chisocheton balansae C.DC., is one of the Meliaceae family plants which is the endemic plants from Soputan Mountain, North Sulawesi, Indonesia. This study was aimed to determine the chemical structure of flavan-3-ol compounds from ethyl acetate extract of C. balansae C.DC stembark. Dried powder of C. balansae C.DC stem bark was extracted consecutively with n-hexane, ethyl acetate, and methanol solvents. Four flavan-3-ol compounds, named catechin (1), epicatechin (2), epigallocatechin-3-O-gallate (3), and epicatechin-3-O-gallate (4) were successfully isolated from ethyl acetate extract. The chemical structure of these isolates was determined by spectroscopic methods (1H-NMR, 13C-NMR, DEPT, and 2D-NMR) and comparison with previous reported spectral data. These compounds are first time reported from this plant.

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