Ta Nang gold deposit in the black shales of Central Vietnam

Russian Geology and Geophysics - Tập 56 - Trang 1414-1427 - 2015
Tran Tuan Anh1, I.V. Gaskov2,3, Tran Trong Hoa1, A.S. Borisenko2,3, A.E. Izokh2,3, Pham Thi Dung1, Vu Hoang Li1, Nguyen Thi Mai1
1Institute of Geological Sciences, Vietnam Academy of Science and Technology, 84 Chua Lang, Dong Da, Hanoi, Vietnam
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia

Tóm tắt

Abstract The Ta Nang gold deposit is localized in Middle Jurassic black shales. The ore zone is a series of layer-by-layer crush zones and zones of hydrothermal rock alteration, ≤10 m in thickness and >2 km in length. It consists of quartz–sulfide veins, sulfidized black shales, and their hydrothermally altered varieties. Sulfide mineralization occurs as two assemblages: early pyrite–arsenopyrite and late chalcopyrite–sphalerite– galena. The pyrite–arsenopyrite assemblage is composed of different morphogenetic varieties. Coarse-crystalline arsenopyrite and pyrite aggregates and metacrystals of different orientations, 0.1 to 10 mm in size, are the most widespread. The chalcopyrite–sphalerite–galena assemblage is scarce. Along with the main ore minerals, it includes more rare minerals: pyrrhotite, lead sulfosalts (tsugaruite), and gold, which form a spatial assemblage with the main minerals or small inclusions in them. Gold occurs mainly as fine dissemination in cracks in pyrite, arsenopyrite, chalcopyrite, and quartz. Gold content in sulfidized carbonaceous shales is no more than tenths of ppm, averaging 0.38 ppm. This content in the quartz veins is considerably higher, averaging 3.92 ppm. Silver contents in the shales and quartz veins are similar and equal to 2.68 and 5.30 ppm, respectively. Also, the sulfidized rocks and veins have elevated contents of Fe, As, Pb, Zn, Cu, Cd, Ni, and Co; most of these elements (Fe, As, Pb, Zn, and Cu) make up their own sulfide minerals, and the others are trace elements. According to 39Ar/40Ar dating of sericite from the quartz–sulfide veins, their age is 129.3 ± 5.6 Ma, which is close to the age of the Cretaceous granite intrusions of the Deo Ca complex. These veins formed from moderately strong solutions (11.7–6.4 wt.% NaCl equiv) with the CH4 + N2 + CO2 gas phase at 340–130 °C. Judging from the S isotope composition (δ34S = 1.6–4.3‰), predominantly deep-seated endogenic sulfur participated in the formation of ore sulfide associations. Analysis of the distribution of gold shows that it was deposited together with sulfide minerals (galena, sphalerite, and chalcopyrite) at a later stage.

Tài liệu tham khảo

Ashley, 2000, Invisible gold in ore and mineral concentrates from the Hillgrove gold-antimony deposits, NSW Australia, Mineral. Deposita, 35, 285, 10.1007/s001260050242 Boyle, 1979, The geochemistry of gold and its deposits (together with a chapter on geochemical prospecting for the element), 10.4095/105577 Boynton, 1984, Cosmochemistry of the rare earth elements; meteorite studies, Rare Earth Element Geochemistry, 63, 10.1016/B978-0-444-42148-7.50008-3 Buryak, 1997, Sukhoi Log—One of the Largest Gold Deposits in the World: Genesis, Mechanisms of Mineralization, Prediction Criteria [in Russian] Buryak, 2002, Genesis, patterns of distribution and prospects for gold- and platinum-bearing black shale strata, Rudy i Metally, 25 Gaskov, 2006, Gold-bearing mineral assemblages of Cu-ore deposits in the Altai–Sayan folded area, Russian Geology and Geophysics (Geologiya i Geofizika), 47, 982 Genkin, 2002, Gold-bearing Arsenopyrite and Its Formation Condition at the Olympiada and Veduga Gold Deposits (Yenisei Range, Siberia), Geology of Ore Deposits, 44, 52 Goryachev, 2010, The epithermal Au–Ag mineralization in volcanic belts of northeast Asia, Lithosfera, 36 Ivensen, 1975, Genetic types of gold mineralization and gold ore formations, in: Gold Ore Formations and Geochemistry of Gold from the Verkhoyansk–Chukotka Fold Area [in Russian], 5 Konstantinov, 1997, Genetic types of gold-silver deposits of volcanoplutonic belts. Izvestiya Vysshikh Uchebnykh Zavedeniy, Geologiya i Razvedka, 62 Konstantinov, 2009, Gold-Ore Giants of Russia and the World [in Russian] Kovalev, 2011, Gold-bearing arsenopyrite in eastern Kazakhstan gold-sulfide deposits, Russian Geology and Geophysics (Geologiya i Geofizika), 52, 178, 10.1016/j.rgg.2010.12.014 Lindgren, 1933, Mineral Deposits, fourth Narseev, 1997, On the geochemistry of gold of terrigenous rocks, Geology, Geochemistry, and Mineralogy of Gold Ore Regions and Deposits of Kazakhstan, 18 Nekrasov, 1991, Geochemistry, Mineralogy and Genesis of Gold Ore Deposits [in Russian] Son, 2011, Geology and Earth Resources of Viet Nam Hoang, 2009, Mineralogical Characteristics and Prospects of Gold-Mining Deposit Ta Nang, Lam Dong Province [in Vietnamese] Novozhilov, 1996, Gold-sulphide deposits—a major source of raw gold mining industry of the XXI century. Mineral Resources in the XXI Century: Federal Geological Service of Russia. MGK-XXX, Beijing, 4–14 August (Abstracts), Otechestvennaya Geologiya, 16 Petrovskaya, 1973, Native Gold: General Characteristics, Typomorphism, Issues of Genesis [in Russian] Safonov, 1997, Hydrothermal gold deposits: distribution, geologicalgenetic types, and productivity of ore-forming, Geology of Ore Deposits, 39, 20 Sorokin, 2013, The regularities of formation of noble- and rare-metal mineralization in Cenozoic coaliferous deposits in the southern Far East, Russian Geology and Geophysics (Geologiya i Geofizika), 54, 671, 10.1016/j.rgg.2013.06.003 Spiridonov E.M. , 2010. Review of mineralogy of gold in the leading types of Au mineralization, in: Proc. All-Russ. Sci. Conf. (with foreign participation), devoted to the 80th Anniversary of the Kola Scientific Center of the Russian Academy of Sciences. K&M, Apatites, pp. 143–171. Starova, 1977, The role of typomorphic features of pyrite and arsenopyrite of gold-ore deposits in deciphering the genesis of ores, Geology, geochemistry and mineralogy of gold ore regions and deposits in Kazakhstan, 97 Tran Trong Hoa , Tran TuanAnh, Ngo ThiPhuong, Pham ThiDung, Tran VietAnh, 2005. Permian–Triassic magmatic activities in Viet Nam and prospect of associated precious metal (Pt, Au) mineralization, in: Proc. Sci. Conf. 60th Anniversary of Geology of Vietnam [in Vietnamese]. Hanoi, pp. 63–79. Tyukova, 2007, Composition and parageneses of arsenopyrite in the deposits and host rocks of Verkhnekolymsky region (interpretation of the genesis of sulfide assemblages) Vilor, 2014, Aresenopyrite–pyrite paragenesis in gold deposits (thermodynamic modeling), Russian Geology and Geophysics (Geologiya i Geofizika), 55, 824, 10.1016/j.rgg.2014.06.003 Volkov, 2006, On the forms of gold, found in ores in Natalka and Mayski deposits (Northeast Russia), Tikhookeanskaya Geologiya, 25, 18 Vos, 2005, Genesis of orogenic-gold deposits in the Broken River Province, northeast Queensland, Aust. J. Earth Sci., 52, 941, 10.1080/08120090500375190 Hung, 2003, Volcanic-arc rocks in the Da Lat Late Mesozoic active continental margin, Geology, Resources, and Ecology of Southern Vietnam [in Vietnamese], 31
Thông tin
Thông tin xuất bản

Russian Geology and Geophysics

Tập 56

1414-1427

Thông tin tác giả