Metallogenesis and hydrothermal evolution of the Tonggou Cu deposit in the Eastern Tianshan: Evidence from fluid inclusions, H-O-S isotopes, and Re-Os geochronology

• Published in: Di xue qian yuan. Vol. 10; no. 6; pp. 2301 - 2312
• Main Authors: Zhang, Xue-bing, Chen, Chuan, Xia, Fang, Gao, Ling-ling, Quan, Hong-yan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.11.2019; Elsevier Science Ltd; College of Geology and Mining Engineering,Xinjiang University,Urumqi 830047,China%School of Biological,Earth and Environmental Sciences,UNSW,Kensington,NSW 2052,Australia
• Subjects: Calcite; Chalcopyrite; Chalcopyrite Re-Os geochronology; Copper; Exploratory drilling; Fluid inclusion; Fluid inclusions; Fluids; Geochronology; Gold; High temperature; Isotopes; Meteoric water; Mineralization; Orogeny; Petrography; Pyrite; Sandstone; Stable isotope; Sulfidation; Sulfur; Sulfur isotopes; The Eastern Tianshan; Tonggou deposit; Tonggou deposit; Stable isotope; The Eastern Tianshan; Chalcopyrite Re-Os geochronology; Fluid inclusion
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2019.04.008

The Tonggou Cu polymetallic deposit in the Bogda Orogenic Belt, Eastern Tianshan shows evidence for three stages of hydrothermal mineralization: early pyrite veins (Stage 1), polymetallic sulfide ± epidote–quartz (Stage 2), and late-stage pyrite–calcite veins (Stage 3). Fluid inclusion petrography and microthermometry analyses indicate that the liquid-rich aqueous inclusions (L), vapour-rich aqueous inclusions (V), and NaCl daughter mineral–bearing three phase inclusions (S) formed during the main stage of mineralization, and that the ore fluids represent high-temperature and high-salinity H2O-NaCl hydrothermal fluids that underwent boiling. Stable isotope (H, O) data indicate that the ore fluids of the Tonggou deposit were originally derived from magmatic water in Stage 2 and subsequently mixed with local meteoric water during Stage 3. Sulphur isotope compositions (6.7‰ to 10.9‰) are consistent with the δ34S values of pyrite from the Qijiaojing Formation sandstone, indicating the primary source of the sulphur ore. Furthermore, chalcopyrite grains separated from the chalcopyrite-rich ore samples yield an isochron age of 303 ± 12 Ma (MSWD = 1.2). These results indicate that the Tonggou deposit is a transition between high–sulfidation and porphyry deposits which formed in the Late Carboniferous. It also suggests an increased likelihood for the occurrence of Cu (Au, Mo) in the Bogda Orogenic Belt, especially at locations where the Cu-Zn deposits are thicker; further deep drilling and exploration are encouraged in these areas. [Display omitted] •The ore fluids represent high–temperature H2O–NaCl hydrothermal fluids that underwent boiling.•The Tonggou deposit is a transition from high–sulfidation to porphyry mineralization.•The copper polymetallic mineralization occurred in the Late Carboniferous (ca. 303 Ma).