Mineralization Age and Hydrothermal Evolution of the Fukeshan Cu (Mo) Deposit in the Northern Great Xing’an Range, Northeast China: Evidence from Fluid Inclusions, H–O–S–Pb Isotopes, and Re–Os Geochronology

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.

Fluid Inclusions and C–H–O–S–Pb Isotopes of the Huoluotai Porphyry Cu (Mo) Deposit in the Northern Great Xing’an Range, NE China: Implications for Ore Genesis

“…The δ 34 S V-CDT values (0.2‰ to 3.7‰) of the seven sulfides from the Huoluotai Cu (Mo) deposit overlap those of typical porphyry deposits in the NGXR, such as the Badaguan (-2.4‰ to 3.5‰; [45]), the Chalukou (-1.9‰ to 3.6‰; [43]), the Xiaokele (-1.2‰ to 2.4‰; [5]), and the Fukeshan (-2.3‰ to 3.4‰; [4]) deposits (Figure 10). These values are also consistent with the δ 34 S V-CDT values of typical porphyry deposits elsewhere in the world (−5‰ to 5‰; [39]).…”

“…Previous studies have shown that the relatively depleted isotopic values of fluids could have been caused by water-rock interactions or magma degassing [57,58]. The depleted δ 18 O H 2 O and δD isotopic characteristics were extensively recorded by fluids from an early stage in porphyry deposits of the NGXR [59], such as the Xiaokele Cu (Mo) (-1.2‰ to 2.4‰; [5]), the Fukeshan Cu (Mo) (-2.3‰ to 3.4‰; [4]), and the Chalukou Mo (-1.9‰ to 3.6‰; [43]) deposits, which were interpreted to be predominantly of magmatic origin. The δD and δ 18 O H 2 O values for stages II, III, and IV were relatively lower than those for stage I and plotted in the region between the meteoric water line and the magmatic water field (close to the magmatic water field) (Figure 8), suggesting the involvement of some meteoric water but still dominated by magmatic water.…”

“…148 Ma; [2]), the Fukeshan Cu (Mo) (ca. 149 Ma; [3,4]), and the Xiaokele Cu (Mo) (ca. 150 Ma; [5]) deposits.…”

The Influence of Fluid-Exsolving Depth on Mineralization Quality: Evidence from Biotite and Zircon Mineralogy and Fluid Inclusions from the 460 Gaodi Porphyry Mo-Cu Deposit, NE China

“…Northeast China (Figure 1a) is the largest Mo metallogenic province in the world [1,2] and also an important Cu metallogenic province in China [3]. In particular, in the northern Great Xing'an Range (GXR), several porphyry Cu-Mo deposits have been identified, including Duobaoshan Cu-Mo-(Au) [4], Tongshan Cu-Mo [5], Wunugetushan Cu-Mo [6,7], Xiaokelehe Cu-Mo [8], Fukeshan Cu-Mo [9], Yili Mo [10], and numerous ore occurrences. While other factors must be taken into account, an examination of the geology of these deposits reveals that some have not yet been mined, due to a discrepancy between their mineralization quality and the requirements for industrial mining.…”