Geology, Fluid Inclusion and Stable Isotope Constraints on the Fluid Evolution and Resource Potential of the Xiadian Gold Deposit, Jiaodong Peninsula

Abstract

The Xiadan gold deposit from Jiaodong Peninsula contains more than 200 t of gold, and is one of the representative largest deposits within south part of the Zhaoping Fault zone. The gold orebodies consist of auriferous altered rocks that show disseminated and stockwork mineralization. Mineralization and alteration are structurally controlled by the NE‐ to NNE‐striking Linglong detachment fault. Mineralization can be divided into three stages: (K‐feldspar)–sericite–quartz–pyrite, quartz–gold–polymetallic sulfide, and quartz–carbonate, with the majority of the gold being produced during the middle stage. Based on a combination of petrography, microthermometry, and laser Raman spectroscopy, three types of fluid inclusion were identified in the vein mineral assemblages: NaCl–H2O (A‐type), CO2–H2O–NaCl (AC‐type), and pure CO2 (PC‐type). Quartz crystals in veins that formed during the early stage contain mainly AC‐type primary fluid inclusions, with rare PC‐type inclusions. These fluid inclusions homogenize completely at temperatures of 253°C–408°C and have medium–low salinities (1.62–11.89 wt.% NaCl equivalent). Quartz crystals that formed during the middle stage contain all three types of fluid inclusion, and these fluid inclusions homogenize completely at temperatures of 176°C–335°C and have salinities of 0.70–14.73 wt.% NaCl equivalent. In contrast, quartz that formed during the last stage contains only A‐type fluid inclusions; these inclusions have homogenization temperatures of 108°C–253°C and salinities of 1.73–11.60 wt.% NaCl equivalent. The above data indicate that the ore‐forming system evolved from a CO2‐rich mesothermal fluid into a CO2‐poor fluid as a result of an influx of meteoric water. Fluid immiscibility is an essential prerequisite for metals precipitation in Xiadian. The characteristics of fluid inclusions, combined with H–O–S isotopes suggest that the ore‐forming fluids might be of metamorphic origin. Based on the immiscibility of AC‐type fluid inclusions, trapping pressures have been estimated at 88–339 MPa during ore formation, with a depth of metallogenesis of 8.8–12.6 km. The depth of erosion of study area has been calculated as about 10.3 km between 130 Ma and the present. Considering the gold mineralization occurred at around 130 Ma, the space with deep gold exploration is expectable at Xiadian.

Fluid Inclusions, Stable Isotopes, and Geochronology of the Haobugao Lead‐Zinc Deposit, Inner Mongolia, China

“…Fluid cooling is another important control on ore deposition (Fournier, ). The homogenization temperatures of fluid inclusions of the Haobugao deposit decreased gradually from the earlier skarn stage (I) to the carbonate stage (IV), suggesting that the cooling of ore‐forming fluids may have been another important factor in the formation of this deposit (Chai et al, ; Fig. ).…”

Geology, Fluid Inclusion, and H–O–S–Pb Isotope Constraints on the Mineralization of the Xiejiagou Gold Deposit in the Jiaodong Peninsula

“…The main volatile component of the type ΙΙΙ FIs for the last two stages is H 2 O with minor amounts of CO 2 and H 2 S (Figures 10(e) and 10(f)). 10 Geofluids Figures 9 and 11). Therefore, the initial ore fluids belonged to a homogeneous CO 2 -H 2 O -NaCl ± CH 4 fluid system.…”

“…The Jiaodong Peninsula (Figure 1) is an important gold metallogenic belt in China hosting about 4000 t of gold reserves and also considered as one of the most famous gold mineralization belts in the world [1][2][3][4][5][6][7][8][9][10][11]. The majority of gold deposits in the region are temporally and spatially related to Mesozoic NE-trending faults, and the deposits have been classified as Jiaojia-type and Linglong-type mineralization, where the former refers to a combination of disseminated and stockwork/veinlet gold mineralization and the latter to auriferous quartz veins [1,[12][13][14][15].…”

Two‐Stage Sulfide Mineral Assemblages in the Mineralized Ultramafic Rocks of the Laowangzhai Gold Deposit (Yunnan, SW China): Implications for Metallogenic Evolution

“…Although hydrothermal gold deposits can be hosted in various types of rocks, including meta‐basalt (Pitcairn et al, ; Zhang & Zhu, ), granitoids (Chai et al, ; Jin et al, ; Rezeau et al, ), and volcano‐sedimentary rocks (Cave et al, ; Zhang & Zhu, ; An & Zhu, ), the most common gold‐bearing sulfides in hydrothermal gold deposits hosted by various wall rocks are pyrite and arsenopyrite, which can provide valuable insight about the characteristics and evolution of ore‐forming systems (Large et al, ; King et al, ; Salvi et al, ; Zheng et al, ). In some hydrothermal gold deposits, nickel‐bearing sulfides (e.g., gersdorffite, vaesite) can occur in the mineralized ultramafic rocks (Aydal, ; Zoheir & Lehmann, ).…”