Agung Harijoko
Jurusan Teknik Geologi Fakultas Teknik, Universitas Gadjah Mada

Published : 22 Documents
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Journal : Journal of Southeast Asian Applied Geology

MERCURY AND ARSENIC CONTAMINATION FROM SMALL SCALE GOLD MINING ACTIVITIES AT SELOGIRI AREA, CENTRAL JAVA, INDONESIA Harijoko, Agung; Htun, Tin May; Saputra, Rodhie; Warmada, I Wayan; Setijadji, Lucas Donny; Imai, Akira; Watanabe, Koichiro
Journal of Applied Geology Vol 2, No 1
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1689.074 KB) | DOI: 10.22146/jag.7235

Abstract

Small scale gold mines discussed here are located at Selogiri area, Central Java, Indonesia which was mined by local community mainly during gold rush in 1990s. This Selogiri gold deposit genetically is characterized by porphyry mineralization overprinted by epithermal system. The ore minerals assemblage consists of pyrite, sphalerite, chalcopyrite, galena, chalcocite and rare arsenopyrite. Chemical analysis of soil and stream sediment sampled over 1.5 km across at the Selogiri gold extraction site indicates that the site has been contaminated with mercury due to mining activities. The mercury concentrations in soil and stream sediments collected during dry season range from 0.01 to 481 ppm and 0.01 to 139 ppm, respectively, higher than background value of 0.05 ppm. In contrast, mercury concentration in stream sediments collected during rainy season from the same location as dry season sampling ranges from 0.01 to 13.42 ppm, and one sample has anomalous value of 331 ppm. This result show that rain water may disperse and decrease mercury concentration in stream sediments. In case of arsenic, although the ore contains rare arsenic minerals, arsenic concentration in bulk rock and ore is high ranging from 8 to 59 ppm, while the arsenic concentration in tailing is much higher ranging from 5.8 to 385 ppm. Chemical analyses on pyrite reveal that the pyrite grains contain arsenic and might be the source of arsenic in Selogiri mine site. However, analysis of dug-well water demonstrates that the mercury and arsenic content is still lower than the maximum allowable concentration. Keywords: Mercury, arsenic, contamination, Selogiri, gold mine
Mineral paragenesis and fluid inclusions of the Bincanai epithermal silver-base metal vein at Baturappe area, South Sulawesi, Indonesia Nur, Irzal; Idrus, Arifudin; Pramumijoyo, Subagyo; Harijoko, Agung; Imai, Akira
Journal of Applied Geology Vol 3, No 1
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2830.054 KB) | DOI: 10.22146/jag.7179

Abstract

The Baturappe prospect located at southern part of Sulawesi island, Indonesia, is a hydrothermal mineralization district which is characterized by occurrence of epithermal silver-base metal deposits. The mineralization is hosted in basaltic-andesitic volcanic rocks of the late Middle-Miocene Baturappe Volcanics. More than 20 units of quartz – base metal veins are distributed in the area, and one of the most significant is the Bincanai vein. This study is aimed to characterize the mineral paragenesis and to elucidate the physicochemical conditions of the formation of the deposit on the basis of mineral assemblage and fluid inclusion mictrothermometry. Sulphide assemblages in the vein indicate an intermediate sulfidation state epithermal; beside galena and sphalerite as the early stage minerals, chalcopyrite, tennantite, and tetrahedrite are also identified as the later stage. Microthermometric study of fluid inclusions in quartz indicates formation temperature of the vein ranges from about 230 to 280°C Histogram of homogenization temperature suggests that there are two generations of hydrothermal fluid responsible for the ore mineralization in the vein; the higher temperature range represents formation temperature of the base metal (galena, sphalerite), while the lower temperature range is correlate with the precipitation of the rest relatively lower temperature sulphides (chalcopyrite, pyrite, tetrahedrite, tennantite, polybasite, and Bi-Ag-Cu-Fe-bearing sulfide). The sequence is also consistent with the mineral paragenetic. The mean of salinity (2.0–2.5 wt.% NaCl eq.) indicates that fluid responsible for the mineralization in the Bincanai vein is relatively low-salinity fluid.
VEINS AND HYDROTHERMAL BRECCIAS OF THE RANDU KUNING PORPHYRY Cu-Au AND EPITHERMAL Au DEPOSITS AT SELOGIRI AREA, CENTRAL JAVA INDONESIA Sutarto, Sutarto; Idrus, Arifudin; Harijoko, Agung; Setijadji, Lucas Donny; Meyer, Franz Michael
Journal of Applied Geology Vol 7, No 2 (2015): Current Issue
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.26982

Abstract

The Randu Kuning prospect is situated at Selogiri area, Wonogiri, Central Java, Indonesia. This location is about 40 km to the south-east from Solo city or approximately 70 km east of Yogyakarta city. Many Tertiary dioritic rocks related alterationmineralisation were found at the Randu Kuning area and its vicinity, including hornblende microdiorite, hornblende-pyroxene diorite and quartz diorite. Mineralisation type of the Randu Kuning prospect was interpreted as porphyry Cu-Au and a number epithermal Au-base metals deposits in its surrounding. The closed existing of porphyry Cu-Au and epithermal Au-base metals type deposits at the Randu Kuning area produced a very complex of veins and hydrothermal breccias crosscutting relationship. A lot of porphyry veins types were found and observed at the Randu Kuning area, and classified into at least seven types. Most of the porphyry veins were cross cut by epithermal type veins. Many epithermal veins also are found and crosscut into deeply porphyry vein types. There are genetically at least two type of hydrothermal breccias have recognized in the research area, i.e. magmatic-hydrothermal breccia and phreatomagmatic breccia. Magmatic hydrothermal breccias are mostly occured in contact between hornblende microdiorite or quartz diorite and hornblende-pyroxene diorite, characterized by angular fragments/clasts supported or infilled by silicas, carbonates and sulphides matrix derived from hydrothermal fluids precipitation. Phreatomagmatic breccias are characterized by abundant of the juvenile clasts, indicated contact between hot magma with fluid or water as well as many wall rock fragments such as altered diorites and volcaniclastic rock clasts set in clastical matrix. The juvenile clasts usually compossed by volcanic glasses and aphanitic rocks in rounded-irregular shape. Both veining and brecciation processes have an important role in gold and copper mineralisation of the Randu Kuning Porphyry Cu-Au and epithermal Au-base metals deposits, mostly related to the presence of quartz veins/veinlets containing significant sulphides, i.e., quartz with thin centre line sulphides (Abtype) veins, pyrite±chalcopyrite (C type) veinlets, pyrite+quartz± chalcopyrire±carbonate (D type) veins of porphyry types as well as epithermal environment quarts+ sulphides+carbonate veins.
FLUID INCLUSION STUDIES OF THE EPITHERMAL QUARTZ VEINS FROM SUALAN PROSPECT, WEST JAVA, INDONESIA Tun, Myo Min; Warmada, I Wayan; Idrus, Arifudin; Harijoko, Agung; Verdiansyah, Okki; Watanabe, Koichiro
Journal of Applied Geology Vol 6, No 2
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (952.327 KB) | DOI: 10.22146/jag.7218

Abstract

Sualan prospect is located at Talegong Sub-district of Garut Regency, West Java, Indonesia. The area constitutes calc-alkaline volcanic and volcaniclastic rocks of Tertiary age. The rocks have experienced regional propylitic and argillic alteration. Fluid inclusions from quartz veins were studied in order to constrain the nature, characteristics and evolution of fluids. Microthermometric measurements on fluid inclusion were carried out by freezing and heating experiment. Temperatures of homogenization (Th) and final melting of ice (Tm) were measured for primary, liquid-dominated, two-phase inclusions. The values of Th range from 160°C to 210°C and salinities range from 0.35 to 4.96 wt.% NaCl equiv. Formation temperature of the quartz veins are estimated at 180°C and 190°C and paleo-depth of formation are at 80m and 140m, respectively. Microthermometric data indicates that fluid mixing and dilution were important processes during the evolution of hydrothermal system. Based on fluid inclusion types, microthermometric data, trapping temperature, paleo-depth, texture of quartz and hydrothermal alteration types, quartz veins from prospect were developed under epithermal environment. Keywords: Quartz vein, fluid inclusions, microthermometry, salinities, formation temperature, paleo-depth, epithermal, Sualan prospect.
Characteristics Of Hydrothermal Alteration In Cijulang Area, West Java, Indonesia Tun, Myo Min; Warmada, I Wayan; Harijoko, Agung; Al-Furqan, Reza; Watanabe, Koichiro
Journal of Applied Geology Vol 7, No 1
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.16917

Abstract

Characterization of hydrothermal alteration in theCijulang area (West Java, Indonesia) was carriedout using shortwave infrared spectroscopy. Hydrothermal alteration in the Cijulang area occurs in the calc-alkaline volcanic and volcaniclastic rocks. Shortwave infrared spectroscopic measurements of reflectance for altered rocks and minerals were carried out by ASD-FieldSpec and the laboratory spectra acquired were then analysed with “The Spectral Geologist” software program. Shortwave infrared spectroscopy is capable of detecting most finegrained alteration minerals from different hydrothermal alteration zones. Characteristic alteration minerals identified from the SWIR technique include pyrophyllite, alunite, kaolinite, dickite, illite, montmorillonite, polygorskite, gypsum, epidote, paragonite, and muscovite. Most of the spectra show mixture ofalteration minerals and only a few display pure spectra of single mineral. The crystallinity of kaolinite from the samples was also determined from the reflectance spectra and show moderately to high crystallinity. Alteration system of the Cijulang prospectis similar to others documented high-sulfidation epithermal deposits, such as Rodalquilar (Spain), Summitville (Colorado), and Lepanto (Philippines). A characteristic alteration sequence and zonation of advanced argillic, argillic and propylitic alterationoutward from the silica core has resulted from the progressive cooling and neutralization of hot acidic magmatic fluid with the host rocks.Keywords: Cijulang, High-sulfidation, Alteration minerals, Shortwave Infrared Spectroscopy
The Effect of Differences Leachate Concentration and Material Properties on Electrical Conductivity of Volcanic Deposits – Case Studies Piyungan Landfill Bantul Yogyakarta Parhusip, Jaingot A.; Harijoko, Agung; Eka Putra, Doni Prakasa; Suryanto, Wiwit
Journal of Applied Geology Vol 1, No 1 (2016)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (886.368 KB) | DOI: 10.22146/jag.26956

Abstract

Monitoring at the contaminated subsurface soil, have been conducted by using the geophysical surface method, especially for geoelectrical resistivity method. Monitoring is commonly conducted by using geoelectrical resistivity through measuring the value of Electrical Resistivity (ER) or Electrical Conductivity (EC) of leachate contaminated soil layer. EC measurement value of soil is affected by many factors, among others, particle conduction of soil materials, surface conduction, fluid conduction in the pores as well as the effect of particle shape and soil materials. Piyungan landfill is the main disposal site of Yogyakarta municipal solid waste. This landfill located mainly on the tertiary rocks of volcanic rocks and its weathering products. In order to improve the accuracy of geoelectrical measurements on resistivity in monitoring soil layers from contaminated leachate on this area, this research conducted several measurements on physical properties of soil sample and electrical properties of leachate in the saturated soil samples. The measurement of physical properties includes: porosity, clay content, particle content, and cation exchange capacity (CEC) value. The soil samples were collected from 3 locations around Piyungan Landfill. Type of soils are taken from the alluvial deposits (Sample B), weathered tuffaceous sandstone-claystone (Sample D), and weathered andesitic breccia (Sample F). Samples were made in containers, saturated with aquades-leachate solution with 12 different concentration levels. Electrical conductivity (EC) was measured by using Soil Box Miller and Geoelectric Resistivity Oyo McOhm. According to results of physical properties analysis, the grain size of soils are dominantly sandy clayey silt in grain size distribution, with clay content ranging from 33.0--38.4 %, the CEC values ranging from 26.8--52.7 meq/100 gr, and the porosity of samples B, D and F is 58.85 %, 55.30 %, 59.24 %, respectively. Based on the experiments with 12 different leachate concentrations, there is a linear increase in EC of 0.718mS/cm for every increase in electrical conductivity pore fluid (ECf ) 1 mg/l in samples B, while in samples D and F are 0.492 mS/cm and 0.284 mS/cm respectively. Plotting the data of EC vs ECf for each samples and ER vs ECf , it can be concluded the slope ofDEC/DECf differ for each samples and the electrical conductivity value of different concentration of leachate is very sensitive for alluvial deposits compare to the weathered tuffaceous sandstone-claystone and weathered volcanic breccia deposits.
Variation of Slab Component in Ancient and Modern Merapi Products: A Detailed Look into Slab Derived Fluid Fluctuation over the Living Span of One of the Most Active Volcanoes in Sunda Arc Handini, Esti; Hasenaka, Toshiaki; Harijoko, Agung; Mori, Yasushi
Journal of Applied Geology Vol 2, No 1 (2017)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4965.901 KB) | DOI: 10.22146/jag.30253

Abstract

Holocene eruptions of Merapi have produced both medium-K and high-K calc alkaline series which correspond to products older and younger than 1900 years respectively. The change has been attributed to increasing sediment input as the volcano matures. This study presents two Merapi samples which represent Ancient and Modern Merapi. The two samples are analyzed for subduction components including B, Ba, Sr, and Pb using X-ray fluorescence (XRF) spectrometer and prompt gamma ray analysis (PGA). Our finding shows that Ancient Merapi sample from Plawangan Hill lava is close in affinities with younger than 1900 years high-K magma series. On the other hand, Modern Merapi sample from 2006 eruption juvenile is plotted within medium-K magma series which are observed in eruption products older than 1900 years. Ratios of fluid mobile elements to high field strength element (HFSE) (i.e. B/Nb, Ba/Y, Pb/Nb) consistently show that Ancient Merapi sample has higher input of slab derived fluid than Modern Merapi sample. A model using B/Nb and Ba/Nb suggests that Plawangan magma requires 1.5 % of sediment derived fluid, higher than estimated in 2006 eruption magma (1.2 %) and medium-K series magma, and within the range of high-K series magma, to explain its slab component enrichment. This evidence suggests that slab derived component addition to the sub-arc mantle wedge highly fluctuates over short period of evolution of a volcano. One possible explanation is the presence of veined hydrous metasomatized sub-arc mantle as Merapi magma source which allows melting of different mantle area to produce fluctuation of slab components in the course of evolution of Merapi magmas.
HIGH SULFIDATION EPITHERMAL MINERALIZATION AND ORE MINERAL ASSEMBLAGES OF CIJULANG PROSPECT, WEST JAVA, INDONESIA Tun, Myo Min; Warmada, I Wayan; Idrus, Arifudin; Harijoko, Agung; Verdiansyah, Okki; Watanabe, Koichiro
Journal of Applied Geology Vol 6, No 1
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4446.559 KB) | DOI: 10.22146/jag.7215

Abstract

Cijulang is a high-sulfidation epithermal system hosted in the calc-alkaline rocks of andesite lava and lapilli tuff. Mineralization in the prospect is characterized by pyrite-enargite-gold and associated acid sulfate alteration. Studies on ore and gangue mineral assemblages and their mutual textural relationships were carried out in order to explore the paragenetic sequence of mineralization. Hypogene mineralization primarily occurs in the silicic core and the advanced argillic zone in the form of massive replacement, fracture-filling veinlets, vug-filling, patches and dissemination. Mineralization is apparently controlled by both lithology and structures. Common ore minerals include pyrite, enargite, luzonite, tennantite, chalcopyrite, covellite, galena, emplectite and Te-bearing minerals. The paragenetic study indicates that the epithermal prospect evolved from an early stage of intense acid leaching resulting in the formation of vuggy silica and advantage argillic mineral assemblage which was followed by the sulfides deposition. Two metal stages were identified during ore deposition: an early Fe-As-S stage and the later Cu-Fe-As-S stage. The former stage is char- acterized high-sulfidation state sulfides such as enargite/ luzonite+covellite whereas a later stage of Cu- Fe-As–S is represented by intermediate sulfidation state sulfides assemblage of tennantite+chalcopyrite. Gold is probably introduced in the early stage within the ore system and more abundant in the late stage. Keywords: Cijulang, high-sulfidation, acid sulfate, mineralization, enargite, paragenetic, metal stages
Hydrothermal Alteration and Mineralization of the Randu Kuning Porphyry Cu-Au and Intermediate Sulphidation Epithermal Au-Base Metals Deposits in Selogiri, Central Java, Indonesia Sutarto, Sutarto; Idrus, Arifudin; Harijoko, Agung; Setijadji, Lucas Donny; Meyer, Franz Michael; Sindern, Sven; Putranto, Sapto
Journal of Applied Geology Vol 1, No 1 (2016)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.26951

Abstract

The Randu Kuning Porphyry Cu-Au prospect area is situated in the Selogiri district, Wonogiri regency, Central Java, Indonesia, about 40 km to the South-East from Solo city, or approximately 70 km east of Yogyakarta city. The Randu Kuning area and its vicinity is a part of the East Java Southern Mountain Zone, mostly occupied by both plutonic and volcanic igneous rocks, volcaniclastic, silisiclastic and carbonate rocks. Magmatism-volcanism products were indicated by the abundant of igneous and volcaniclastic rocks of Mandalika and Semilir Formation. The Alteration zones distribution are generally controlled by the NE–SW and NW–SE trending structures. At least eight types of hydrothermal alteration at the Randu Kuning area and its vicinity had been identified, i.e. magnetite + biotite ± K-feldspar ± chlorite (potassic), chlorite + sericite + magnetite ± actinolite, chlorite + magnetite ± actinolite ± carbonate (inner propylitic), chlorite + epidote ± carbonate (outer propylitic), sericite + quartz + pyrite (phyllic), illite + kaolinite ± smectite (intermediate argillic), illite + kaolinite ± pyrophyllite ± alunite (advanced argillic) and quatz + chlorite (sillisic) zones. The Randu Kuning mineralization at Selogiri is co existing with the porphyry Cu-Au and intermediate sulphidation epithermal Au-base metals. Mineralization in the porphyry environment is mostly associated with the present of quartz-sulphides veins including AB, C, carbonate-sulphides veins (D vein) as well as disseminated sulphides. While in the epithermal prospect, mineralization is particularly associated with pyrite + sphalerite + chalcopyrite + carbonate ± galena veins as well as hydrothermal breccias. The Randu Kuning porphyry prospect has copper gold grade in range at about 0.66–5.7 gr/t Au and 0.04–1.24 % Cu, whereas in the intermediate sulphidation epithermal contain around 0.1–20.8 gr/t Au, 1.2–28.1 gr/t Ag, 0.05–0.9 % Zn, 0.14–0.59 % Pb and 0.01–0.65 % Cu.
Hydrogeochemical Characterization of GeothermalWater in Arjuno-Welirang, East Java, Indonesia Martadiastuti, Vanadia; Harijoko, Agung; Warmada, I Wayan; Yonezu, Kotaro
Journal of Applied Geology Vol 2, No 2 (2017)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.39979

Abstract

Arjuno-Welirang Volcanic Complex (AWVC) is one of geothermal fields whichlocated in East Java province, Indonesia. It belongs to a Quarternary volcanic arc and has potential for development of electricity. The field is situated in a steep volcanic terrain and there are only few geothermal manifestations, i.e., hot springs, fumaroles, solfataras, steaming ground and hydrothermal alteration. This study aims to classify the type and source of geothermal fluid and to estimate the reservoir condition of Arjuno- Welirang geothermal system. Data are obtained from collecting water samples including hot springs, cold springs, river waters and rain water, then they are analyzed using ICP-AES, titration and ion chromatography.All thermal waters have temperatures from 39.5–53°C and weakly acidic pH (5.2–6.5). Cangar and Padusanhot springs show bicarbonate water, formed by steam condensing or groundwater mixing. On the other hand, Songgoriti shows Cl-HCO3 type, formed by dilution of chloride fluid by either groundwater or bicarbonate water during lateral flow. All of the waters represent immature waters, indicating no strong outflow of neutral Cl-rich deep waters in AWVC. Cl/B ratios show that all water samples have a similar mixing ratio, showing they are from common fluid sources. However, Padusan and Songgoriti have higher Cl/B ratios than Cangar, suggesting that geothermal fluids possibly have reacted with sedimentary rocks before ascending to the surface. All waters were possibly mixed with shallow groundwater and they underwent rock-water reactions at depth before ascending to the surface. An estimated temperatures reservoir calculated using CO2 geothermometer yielded temperatures of 262–263 °C based on collecting of fumarole gas at Mt. Welirang crater. According to their characteristics, Cangar and Padusan are associated with AWVC, while Songgoriti is associated with Mt. Kawi.