Abstract
The Fukeshan Cu (Mo) deposit is a newfound porphyry deposit in the northern Great Xing’an Range (GXR), northeast China. In this paper, we present results of chalcopyrite Re–Os geochronology, microthermometry of the fluid inclusions (FIs), and isotopic (H–O–S–Pb) compositions of the Fukeshan Cu (Mo) deposit. Its ore-forming process can be divided into sulfide-barren quartz veins (A vein; stage I), quartz + chalcopyrite + pyrite veins (B vein; stage II), quartz + polymetallic sulfide veins (D vein; stage III), and barren quartz + carbonate ± pyrite veins (E vein; stage IV), with Cu mineralization mainly occurred in stage II. Three types of FIs are identified in this deposit: liquid-rich two-phase (L-type) FIs, vapor-rich two-phase (V-type) FIs, daughter mineral-bearing three-phase (S-type) FIs. The homogenization temperatures of primary FIs hosted in quartz of stages I–IV are 381–494 °C, 282–398 °C, 233–340 °C, and 144–239 °C, with salinities of 7.2–58.6, 4.8–9.9, 1.4–7.9, and 0.9–3.9 wt. % NaCl equivalent, respectively. FIs microthermometry and H–O isotope data suggest that the ore-forming fluids were magmatic in origin and were gradually mixed with meteoric water from stages II to IV. Sulfur and lead isotope results indicate that the ore-forming materials of the Fukeshan Cu (Mo) deposit were likely to have originated from Late Jurassic intrusive rocks. The available data suggest that fluid cooling and incursions of meteoric water into the magmatic fluids were two important factors for Cu precipitation in the Fukeshan Cu (Mo) deposit. Chalcopyrite Re–Os dating yielded an isochron age of 144.7 ± 5.4 Ma, which is similar to the zircon U–Pb age of the quartz diorite porphyry, indicating that Late Jurassic quartz diorite porphyry and Cu mineralization occurred contemporaneously.
Highlights
Being the largest Phanerozoic accretionary orogenic belt worldwide, the Central Asian OrogenicBelt (CAOB) documents the formation and evolution of Eurasia systematically [1,2,3], and is located between the Siberian Craton and the Tarim-North China Craton (Figure 1A) [4,5]
China located in the east of the Central Asian OrogenicBelt (CAOB) (Figure 1A), and the Great Xing’an Range (GXR) situated in western NE China (Figure 1B), is an important polymetallic metallogenic belt in China [6,7], hosting a number of epithermal and orogenic Au deposits (e.g., Shabaosi Au deposit; Sandaowanzi Au deposit) [8,9], porphyry deposits (e.g., Duobaoshan Cu–Mo–(Au) deposit; Wunugetushan Cu–Mo deposit) [10,11], hydrothermal Ag–Pb–Zn deposits
According to the analysis of the eutectic temperatures, we can assume the fluids as approximating the simple H2 O–NaCl system, so we used the program HOKIEFLINCS_H2 O–NaCl to estimate the salinities of L- and V-type fluid inclusions (FIs) [43]
Summary
Being the largest Phanerozoic accretionary orogenic belt worldwide, the Central Asian Orogenic. The source of the ore-forming materials, and the origin and evolution of the ore-forming fluids have not been constrained To address these issues, based on detailed core logging, this paper presents microthermometry of the fluid inclusions, isotopic (H–O–S–Pb) compositions, and chalcopyrite Re–Os geochronology. These results allowed us to further discuss the evolution of the ore-forming fluids and the possible metallogenic mechanism. This information can provide further prospecting direction of Late Mesozoic porphyry deposits in the northern GXR. F4, Mudanjiang–Yilan; F5, Solonker–Xar Moron–Changchun–Yanji; F6, Jiamusi–Yilan; and F7, Heihe; F4, Mudanjiang–Yilan; F5, Solonker–Xar Moron–Changchun–Yanji; F6, Jiamusi–Yilan; and F7, Dunhua–Mishan. (C) Geological map of the northern Great Xing’an Range (modified from [22]), showing the distribution of major ore deposits
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