Fluid Inclusions and Stable Isotopic Characteristics of the Yaoling Tungsten Deposit in South China: Metallogenetic Constraints. Issue 1 (6th September 2018)

• Record Type: Journal Article
• Authors: Yang, Feng; Zhai, Wei; Sun, Xiaoming; Klemd, Reiner; Sun, Yanyan; Wu, Yunshan; Hua, Renmin; Zheng, Siqi
• Is Part Of: Resource geology. Volume 69:Issue 1(2019:Jan.)
• Page Start: 107
• Page End: 122
• Publication Date: 2018-09-06
• Subjects: fluid inclusion -- immiscibility -- stable isotope -- Yaoling tungsten deposit; Mining geology -- Periodicals; Mining geology -- Pacific Area -- Periodicals; Mining geology -- Asia -- Periodicals; Geochemistry -- Periodicals; Environmental geology -- Periodicals; 553
• DOI: 10.1111/rge.12188
• Languages: English
• ISSNs: 1344-1698

Abstract

Abstract: The Yaoling tungsten deposit is a typical wolframite quartz vein‐type tungsten deposit in the South China metallogenic province. The wolframite‐bearing quartz veins mainly occur in Cambrian to Ordovician host rocks or in Mesozoic granitic rocks and are controlled by the west‐north‐west trending extensional faults. The ore mineralization mainly comprises wolframite and variable amounts of molybdenite, chalcopyrite, pyrite, fluorite, and tourmaline. Hydrothermal alteration is well developed at the Yaoling tungsten deposit, including greisenization, silicification, fluoritization, and tourmalinization. Three types of primary/pseudosecondary fluid inclusions have been identified in vein quartz, which is intimately intergrown with wolframite. These include two‐phase liquid‐rich aqueous inclusions (type I), two‐ or three‐phase CO2 ‐rich inclusions (type II), and type III daughter mineral‐bearing multiphase high‐salinity aqueous inclusions. Microthermometric measurements reveal consistent moderate homogenization temperatures (peak values from 200 to 280°C), and low to high salinities (1.3–39 wt % NaCl equiv.) for the type I, type II, and type III inclusions, where the CO2 ‐rich type II inclusions display trace amounts of CH4 and N2 . The ore‐forming fluids are far more saline than those of other tungsten deposits reported in South China. The estimated maximum trapping pressure of the ore‐forming fluids is about 1230–1760 bar, corresponding to a lithostatic depth of 4.0–5.8 km. The δDH2O isotopic compositions of the inclusion fluid ranges from −66.7 to −47.8‰, with δ 18 OH2O values between 1.63 and 4.17‰, δ 13 C values of −6.5–0.8‰, and δ 34 S values between −1.98 and 1.92‰, with an average of −0.07‰. The stable isotope data imply that the ore‐forming fluids of the Yaoling tungsten deposit were mainly derived from crustal magmatic fluids with some involvement of meteoric water. Fluid immiscibility and fluid–rock interaction are thought to have been the main mechanisms for tungsten precipitation at Yaoling. Abstract : The Yaoling tungsten deposit is a typical wolframite quartz vein‐type tungsten deposit in the South China metallogenic province. There were three types of fluid inclusions identified: Type I: two‐phase liquid‐rich aqueous inclusions, type II: two‐or three‐phase CO2‐rich inclusions, and type III: daughter mineral‐bearing multiphase high‐salinity aqueous inclusions. The ore‐forming fluids are of a moderate temperature and low to high salinity NaCl–H2 O–CO2 system and are mainly derived from magmatic brines, with little involvement of meteoric water. Immiscibility is the main mechanism of wolframite precipitation at Yaoling.