Low-sulfidation epithermal gold deposits in Java, Indonesia: Characteristics and linkage to the volcano-tectonic setting

Prihatmoko, Sukmandaru; Idrus, Arifudin

doi:10.1016/j.oregeorev.2020.103490

Cited by 23 publications

(18 citation statements)

References 30 publications

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“…Sedimentary rocks of Toraja formation formed in the back-arc basin rift environment evidently become to be fertile host rocks for gold mineralisation in the region. This fact is supported by current study results indicate that back-arc basin rift could be a favorable volcanotectonic environment for the formation of an economic LS epithermal gold deposit (e.g., Sillitoe and Hedenquist, 2003;Prihatmoko and Idrus, 2020). Lithologic control and extensional structural deformation forming dilational jogs are the important geological factors for the for- .…”

Section: Implication For Explorationsupporting

confidence: 78%

Low-Sulfidation Epithermal Carbonate-Basemetal-Gold Mineralization Hosted by Tertiary Sedimentary Rocks in Bastem Prospect, Luwu District, Sulawesi Island, Indonesia: A Preliminary Study

et al. 2020

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In Indonesia, gold is typically mined out from epithermal, porphyry and skarn deposit types occurred within volcanic belts along magmatic arc or active continental margin setting. Numerous gold prospects, however, are recently discovered in association with metamorphic and sedimentary rocks. This paper is aimed to discuss a preliminary study on the occurrences and characteristics of the sedimentary rock-hosted low-sulfidation (LS) epithermal gold mineralization in Bastem (Bessengan Tempe) prospect, Luwu district, Sulawesi Island, Indonesia. Detailed geological and hydrothermal alteration mapping was performed to understand the distribution and characteristics of ore mineralization. Representative ore samples taken were analysed for ore chemistry by means of Fire Assay – Atomic Absorption Spectrometry (FA-AAS) and Acid Geochemical Digest - Atomic Absorption Spectrometry (GA-AAS). The results from this work that the Bastem prospect is stratigrapically occupied by Tertiary sedimentary rocks of Toraja formation, which is adjacent to volcanic rocks of Lamasi formation. Gold-bearing quartz±carbonate veins are hosted by mudstone and siltstone of Toraja formation. The quartz-carbonate veins show a typical LS epithermal open space filling texture containing erratic gold grade of up to 7.16 g/t with relatively high besemetals (Pb and Zn) grades of up to >0.4 and >1%, respectively. Based on those various features, the LS epithermal deposit is categorized as “carbonate-basemetal-gold mineralization type”, which might be originated in back arc rift/basin setting. This ‘unconventional’ sedimentary rock hosted-gold mineralization type would be the new target of gold exploration in Indonesia.

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Section: Implication For Explorationsupporting

confidence: 78%

Low-Sulfidation Epithermal Carbonate-Basemetal-Gold Mineralization Hosted by Tertiary Sedimentary Rocks in Bastem Prospect, Luwu District, Sulawesi Island, Indonesia: A Preliminary Study

et al. 2020

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“…Based on the characteristics of quartz vein floats, vein texture, wall rock alteration types and ore minerals identified, the hydrothermal deposit occurred in the study area is possible of low sulphidation epithermal gold type (cf. White and Hedenquist, 1995;Simmons, White and John, 2005;Hedenquist and Arribas, 2017;Prihatmoko and Idrus, 2020). In order to clarify the content of gold, silver and other base metals, a total of 16 vein samples have been selected for chemical analysis.…”

Section: Hydrothermal Alteration and Quartz Vein Floatsmentioning

confidence: 99%

Lithogeochemical exploration for delineating primary gold occurrences in West Kao area, North Halmahera District, North Maluku Province

Idrus¹,

Fadlin

2021

IMJ

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Halmahera Island retains several gold deposits. One of the gold deposits is called as low sulphidation epithermal (LSE) quartz veins which is currently being mined and is situated in the Gosowong goldfield. The veins mostly originated in N-S and NNE-SSW direction. This study is aimed to determine the prospect area in the northern portion of Gosowong goldfield covering the West Kao sub district based on surface mapping and rock/float- and BLEG stream sediment survey. A total of 16 rock/vein float and 120 BLEG samples were analyzed by FA/AAS and CNO2 cyanide leach methods, respectively. The study area is occupied by tuffaceous sandstone, andesite, porphyritic andesite and lava andesite units. In the eastern part, tuffaceous sandstone is suffered from argillic and propylitic alteration, which may be controlled by the NW-SE-trending structures. The gold grade of rock/float samples is up to 0.044 ppm. BLEG data indicates a calculated threshold of 10 ppb for Au and 72 ppb for Ag. The highest Au and Ag contents (anomalies) are identified in the eastern part of the study area. This is spatially (and maybe genetically) related to the argillic-altered tuffaceous sandstone, structures and occurrences of quartz vein floats. To follow up this finding, a detailed exploration is recommended to be conducted within the prospect area.

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“…Magmatisme daerah ini terbentuk pada Oligosen hingga Miosen (30-8 jtl) [8] dengan batasan yang belum jelas sampai saat ini. Mineralisasi logam berharga di Jawa umumnya berhubungan dengan vulkanik dan tektonik seperti pada deposit dan prospek epitermal di Jawa [9] dan bahkan kemungkinan pada berbagai tipe porfiri yang tersebar di Sabuk Sunda (Gambar 1.a).…”

Section: Pendahuluanunclassified

Indikasi Mineralisasi Tipe Porfiri di Daerah Sumbersari, Kompleks Pengunungan Kulon Progo, Purworejo, Indonesia

Verdiansyah

Muharif

Sukadana³

2020

EKSPLORIUM

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ABSTRAK Pegunungan Kulon Progo merupakan produk magmatisme Busur Sunda-Banda tersusun atas formasi andesit tua. Daerah Sumbersari merupakan bagian dari gunung api Gajah, batuan gunung api tertua Kulon Progo. Indikasi mineralisasi tipe porfiri ditemukan di daerah ini sehingga menarik untuk diteliti lebih lanjut. Penelitian ini bertujuan untuk mengetahui potensi keterdapatan mineral logam berharga (Cu-Au). Metode penelitian yang digunakan adalah pemetaan geologi, analisis petrografi dan mikroskopi bijih, serta analisis geokimia menggunakan XRF dan ICP-MS. Geologi daerah penelitian terletak pada fasies sentral-proksimal Khuluk Gajah, terususun atas intrusi mikrodiorit, mikrodiorit kuarsa, andesit, andesit basaltik-diorit, dan batugamping. Alterasi hidrotermal berkembang pada batuan beku diorit, mikrodiorit, dan sebagian pada andesit. Alterasi hidrotermal dibagi menjadi beberapa kelompok, yaitu ilit-serisit±biotit sekunder, epidot-aktinolit-kalsit±ilit, epidot-kalsit±ilit, dan ilit-serisit±kuarsa. Beberapa fase mineralisasi berkembang, antara lain fase epidot-aktinolit yang diikuti mineralisasi magnetit-kalkopirit, fase biotit-magnetit-kalkopirit-bornit, dan fase akhir serisit-mineral lempung-pirit menggantikan keseluruhan sistem. Analisis geokimia pada batuan teralterasi menunjukan indikasi mineralisasi Cu-Au dengan kadar 491–1447 ppm (0,14%) Cu dan 0,02–0,3 ppm Au dengan rasio elemen Cu:Au adalah 1,01. Karakter geokimia menunjukkan adanya korelasi kuat Cu terhadap Au.ABSTRACT Kulon Progo Mountain is Sunda-Banda Arc magmatism product composed of an old andesite formation. Sumbersari Area is part of the Gajah volcanic, which is the oldest rock of Kulon Progo volcanics. Indication of porphyry type mineralisation has been found in the area which makes the area interested for further research. The research methodologies are geological mapping, petrography and ore microscopy, and geochemical analysis using XRF and ICP-MS. Geology of the area located in central-proximal facies of Khuluk Gajah, consist of microdiorite, quartz-microdiorite, andesite, basaltic-dioritic andesite intrusions, and limestone. Hydrotermal alteration is developing into certain groups like illite-sericite ± secondary biotite, epidote-actinolite-calcite ± illite, epidot-calcite ± illite, and illite-sericite ± quartz. Some mineralisation phases are developed like epidote-actinolite followed by magnetite-chalcopyrite mineralisation, biotite-magnetite-chalcopyrite-bornite phase and the late phase of sericite-clay-pyrite replacing the entire system. Geochemical analysis on altered rocks show Cu-Au mineralisation indication ranging from 491-1,447 ppm (0.14%) and 0.02-0.3 ppm respectively, with Cu:Au ratio is 1.01. Geochemical characteristic shows strong correlation of Cu to Au.

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Low-sulfidation epithermal gold deposits in Java, Indonesia: Characteristics and linkage to the volcano-tectonic setting

Cited by 23 publications

References 30 publications

Low-Sulfidation Epithermal Carbonate-Basemetal-Gold Mineralization Hosted by Tertiary Sedimentary Rocks in Bastem Prospect, Luwu District, Sulawesi Island, Indonesia: A Preliminary Study

Low-Sulfidation Epithermal Carbonate-Basemetal-Gold Mineralization Hosted by Tertiary Sedimentary Rocks in Bastem Prospect, Luwu District, Sulawesi Island, Indonesia: A Preliminary Study

Lithogeochemical exploration for delineating primary gold occurrences in West Kao area, North Halmahera District, North Maluku Province

Indikasi Mineralisasi Tipe Porfiri di Daerah Sumbersari, Kompleks Pengunungan Kulon Progo, Purworejo, Indonesia

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