Late Carboniferous through early Jurassic metallogenesis and tectonics of northeast Asia, Chapter 7 in &lt;i&gt;Metallogenesis and tectonics of northeast Asia&lt;/i&gt;

Dril, S. I.; Ханчук, А. И.; Obolenskiy, Alexander A.; Ogasawara, M.; Rodionov, Sergey M.; Sotnikov, Vitaly I.; Спиридонов, А. М.; Seminsky, Zhan; Timofeev, Vladimir F.; Ershova, Victoria; Nokleberg, Warren J.

doi:10.3133/pp17657

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“…The NKGB is considered to have formed by granitoid intrusive activity during the final closure of the Mongol-Okhotsk Ocean by the collision along the Mongol-Okhotsk belt in the middle Triassic to middle Jurassic (Zorin et al, 2001;Dril et al, 2010;Gordienko et al, 2012;Goldfarb et al, 2013;Hara et al, 2013). The NE trending NKGB is hosted in the Haraa terrane, which is bounded by the Bayangol and the Yeroogol fault systems (Fig.…”

Section: Geological Outline 21 Regional Geologymentioning

confidence: 99%

Gold Mineralization of the Gatsuurt Deposit in the North Khentei Gold Belt, Central Northern Mongolia

et al. 2014

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Mineral assemblages, chemical compositions of ore minerals, wall rock alteration and fluid inclusions of the Gatsuurt gold deposit in the North Khentei gold belt of Mongolia were investigated to characterize the gold mineralization, and to clarify the genetic processes of the ore minerals. The gold mineralization of the deposit occurs in separate Central and Main zones, and is characterized by three ore types: (i) low-grade disseminated and stockwork ores; (ii) moderate-grade quartz vein ores; and (iii) high-grade silicified ores, with average Au contents of approximately 1, 3 and 5 g t −1 Au, respectively. The Au-rich quartz vein and silicified ore mineralization is surrounded by, or is included within, the disseminated and stockwork Au-mineralization region. The main ore minerals are pyrite (pyrite-I and pyrite-II) and arsenopyrite (arsenopyrite-I and arsenopyrite-II). Moderate amounts of galena, tetrahedrite-tennantite, sphalerite and chalcopyrite, and minor jamesonite, bournonite, boulangerite, geocronite, scheelite, geerite, native gold and zircon are associated. Abundances and grain sizes of the ore minerals are variable in ores with different host rocks. Small grains of native gold occur as fillings or at grain boundaries of pyrite, arsenopyrite, sphalerite, galena and tetrahedrite in the disseminated and stockwork ores and silicified ores, whereas visible native gold of variable size occurs in the quartz vein ores. The ore mineralization is associated with sericitic and siliceous alteration. The disseminated and stockwork mineralization is composed of four distinct stages characterized by crystallization of (i) pyrite-I + arsenopyrite-I, (ii) pyrite-II + arsenopyrite-II, (iii) galena + tetrahedrite + sphalerite + chalcopyrite + jamesonite + bournonite + scheelite, and iv) boulangerite + native gold, respectively. In the quartz vein ores, four crystallization stages are also recognized: (i) pyrite-I, (ii) pyrite-II + arsenopyrite + galena + Ag-rich tetrahedrite-tennantite + sphalerite + chalcopyrite + bournonite, (iii) geocronite + geerite + native gold, and (iv) native gold. Two mineralization stages in the silicified ores are characterized by (i) pyrite + arsenopyrite + tetrahedrite + chalcopyrite, and (ii) galena + sphalerite + native gold. Quartz in the disseminated and stockwork ores of the Main zone contains CO2-rich, halitebearing aqueous fluid inclusions with homogenization temperatures ranging from 194 to 327°C, whereas quartz in the disseminated and stockwork ores of the Central zone contains CO2-rich and aqueous fluid inclusions with homogenization temperatures ranging from 254 to 355°C. The textures of the ores, the mineral assemblages present, the mineralization sequences and the fluid inclusion data are consistent with orogenic classification for the Gatsuurt deposit.

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