Fluid inclusions, C–H–O–S–Pb isotope systematics, geochronology and geochemistry of the Budunhua Cu deposit, northeast China: Implications for ore genesis

• Published in: Di xue qian yuan. Vol. 11; no. 4; pp. 1145 - 1161
• Main Authors: Shi, Kaituo, Wang, Keyong, Ma, Xueli, Li, Shunda, Li, Jian, Wang, Rui
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.07.2020; Elsevier Science Ltd; MNR Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Changchun, 130061, China%College of Earth Sciences, Jilin University, Changchun, 130061, China; College of Earth Sciences, Jilin University, Changchun, 130061, China%College of Earth Sciences, Jilin University, Changchun, 130061, China; College of Geology and Mining Engineering, Xinjiang University, Urumqi, 830047, China
• Subjects: Arsenopyrite; Boiling; Budunhua Cu deposit; Calcite; Chalcopyrite; Concentrates (ores); Copper; C–H–O–S–Pb isotopes; Fluid inclusion; Fluid inclusions; Fluids; Geochemistry; Geochronology; Homogenization; Magma; Mineralization; Oxidation; Pyrite; Pyrrhotite; Quartz; Southern great Xing’an range; Whole-rock geochemistry; Zircon; Zircon U–Pb geochronology; China; Budunhua Cu deposit; C–H–O–S–Pb isotopes; Zircon U–Pb geochronology; Southern great Xing’an range; Fluid inclusion; Whole-rock geochemistry; Southern great Xing'an range
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2019.09.010

The Budunhua Cu deposit is located in the Tuquan ore-concentrated area of the southern Great Xing’an Range, NE China. This deposit includes the southern Jinjiling and northern Kongqueshan ore blocks, separated by the Budunhua granitic pluton. Cu mineralization occurs mainly as stockworks or veins in the outer contact zone between tonalite porphyry and Permian metasandstone. The ore-forming process can be divided into four stages involving stage I quartz–pyrite–arsenopyrite; stage II quartz–pyrite–chalcopyrite–pyrrhotite; stage III quartz–polymetallic sulfides; and stage IV quartz–calcite. Three types of fluid inclusions (FIs) can be distinguished in the Budunhua deposit: liquid-rich two-phase aqueous FIs (L-type), vapour-rich aqueous FIs (V-type), and daughter mineral-bearing multi-phase FIs (S-type). Quartz of stages I–III contains all types of FIs, whereas only L-type FIs are evident in stage IV veins. The coexisting V- and S-type FIs of stages I–III have similar homogenization temperatures but contrasting salinities, which indicates that fluid boiling occurred. The FIs of stages I, II, III, and IV yield homogenization temperatures of 265–396 ​°C, 245–350 ​°C, 200–300 ​°C, and 90–228 ​°C with salinities of 3.4–44.3 ​wt.%, 2.9–40.2 ​wt.%, 1.4–38.2 ​wt.%, and 0.9–9.2 ​wt.% NaCl eqv., respectively. Ore-forming fluids of the Budunhua deposit are characterized by high temperatures, moderate salinities, and relatively oxidizing conditions typical of an H2O–NaCl fluid system. Mineralization in the Budunhua deposit occurred at a depth of 0.3–1.5 ​km, with fluid boiling and mixing likely being responsible for ore precipitation. C–H–O–S–Pb isotope studies indicate a predominantly magmatic origin for the ore-forming fluids and materials. LA-ICP-MS zircon U–Pb analyses indicate that ore-forming tonalite porphyry and post-ore dioritic porphyrite were formed at 151.1 ​± ​1.1 ​Ma and 129.9 ​± ​1.9 ​Ma, respectively. Geochemical data imply that the primary magma of the tonalite porphyry formed through partial melting of Neoproterozoic lower crust. On the basis of available evidence, we suggest that the Budunhua deposit is a porphyry ore system that is spatially, temporally, and genetically associated with tonalite porphyry and formed in a post-collision extensional setting following closure of the Mongol–Okhotsk Ocean. [Display omitted] •Ore-causative tonalite porphyry and post-ore dioritic porphyrite were emplaced at 151.1 ​± ​1.1 ​Ma and 129.9 ​± ​1.9 ​Ma, respectively.•Primary magmas of tonalite porphyry originated from partial melting of lower crustal material.•Mineralization fluids and materials were derived principally from a magma source.•The Budunhua porphyry Cu deposit was formed in a post-collisional extensional setting following closure of the Mongol–Okhotsk Ocean.