Geology, Fluid Inclusion, and Sulfur Isotope Studies of the Chehugou Porphyry Molybdenum–Copper Deposit, Xilamulun Metallogenic Belt, NE China

Abstract

The Chehugou Mo-Cu deposit, located 56 km west of Chifeng, NE China, is hosted by Triassic granite porphyry. Molybdenite-chalcopyrite mineralization of the deposit mainly occurs as veinlets in stockwork ore and dissemination in breccia ore, and two ore-bearing quartz veins crop out to the south of the granite porphyry stock. Based on crosscutting relationships and mineral paragenesis, three hydrothermal stages are identified: (i) quartz-pyrite-molybdenite Ϯ chalcopyrite stage; (ii) pyrite-quartz Ϯ sphalerite stage; and (iii) quartz-calcite Ϯ pyrite Ϯ fluorite stage. Three types of fluid inclusions in the stockwork and breccia ore are recognized: LV, two-phase aqueous inclusions (liquid-rich); LVS, three-phase liquid, vapor, and salt daughter crystal inclusions; and VL, two-phase aqueous inclusions (gas-rich). LV and LVS fluid inclusions are recognized in vein ore. Microthermometric investigation of the three types of fluid inclusions in hydrothermal quartz from the stockwork, breccia, and vein ores shows salinities from 1.57 to 66.75 wt% NaCl equivalents, with homogenization temperatures varying from 114°C to 550°C. The temperature changed from 282-550°C, 220-318°C to 114-243°C from the first stage to the third stage. The homogenization temperatures and salinity of the LV, LVS and VL inclusions are 114-442°C and 1.57-14.25 wt% NaCl equivalent, 301-550°C and 31.01-66.75 wt% NaCl equivalent, 286-420°C and 4.65-11.1 wt% NaCl equivalent, respectively. The VL inclusions coexist with the LV and LVS, which homogenize at the similar temperature. The above evidence shows that fluid-boiling occurred in the ore-forming stage. d

Geology, geochemistry and tectonic setting of the Indosinian Mo deposits in southern Great Hinggan Range, NE China

“…The exposed strata in the mining area are Precambrian basement with migmatitic granite (1800 Ma, zircon U–Pb age), and Jurassic andesite, rhyolite, tuff and tuffaceous sandstone (Fig. A; Zeng et al ., 2011a, b). The area is dissected by major NE‐striking faults that are cut by a set of E‐W‐ to NW‐striking faults (Fig.…”

“…In 2007, the No. 243 Geological Team of China Nuclear Geology discovered the Chehugou porphyry Mo–Cu mineralization, which contains 120 000 tonnes Mo metal reserves at an average grade of 0.1% Mo and 250 000 tonnes Cu metal reserves at an average grade of 0.14% Cu (Zeng et al ., ).…”

Petrogenesis of the Yangchang Mo-bearing granite in the Xilamulun metallogenic belt, NE China: geochemistry, zircon U-Pb ages and Sr-Nd-Pb isotopes

“…(), Li and Wang (); Data of granite in northern margin of North China Craton are from Zeng et al . ().…”

“…It contains medium‐ to large‐scale Mo deposits, such as the Chehugou, Xiaodonggou, Jiguanshan, Nianzigou, Yangchang, Baimashi and Kulitu deposits (Zeng et al ., , ). Recent studies (Zeng et al ., , ) show that the ore‐forming epoch in the Xilamulun metallogenic belt includes three stages: Early Triassic, Late Jurassic and Early Cretaceous. The Triassic Mo deposits and granitoids are related to the Paleo‐Asian Ocean tectonic evolution.…”

“…The Late Jurassic Mo deposits and granitoids are related to Paleo‐Pacific tectonic evolution, and the Early Cretaceous Mo deposits and granitoids are related to lithosphere thinning in east China (Zeng et al ., ). Previous studies on the Xilamulun metallogenic belt show that the Mo mineralization is related to the granitoids in genesis (Nie et al ., ; Wu et al ., , ; Qin et al ., ; Zeng et al ., , , ; Zhang et al ., ; Liu et al ., ).…”