Ore Geology, Fluid Inclusion Microthermometry and H-O-S Isotopes of the Liyuan Gold Deposit, Central Taihang Mountains, North China Craton

Abstract

The Liyuan gold deposit, located in the central Taihang Mountains, North China Craton, forms an important part of the Taihang polymetallogenic belt. The origin of ore-forming fluids and the genesis of this deposit remains controversial. In this paper, fluid inclusions (FIs) microthermometry and H-O-S isotopes analysis are conducted to constrain the origin of ore-forming fluids and genesis. The main findings are as follows: (1) Three hydrothermal metallogenic stages are identified: Quartz–pyrite, quartz–polymetallic sulfide, and quartz–carbonate stages; (2) three types of primary FIs are recognized: CO2-aqueous (type I), pure CO2 (type II), and aqueous FIs (type III); (3) ore-forming fluids are characterized by medium–low temperatures, medium–low salinity, and H2O-CO2-NaCl ± CH4 system; (4) H-O isotopes indicate that the ore-forming fluids mainly have a magmatic origin and late-stage ore fluids mixed with meteoric water; (5) S isotopes further confirm that the sulfides most likely have a deep magma source with variation caused by changes in oxygen fugacity; and (6) fluid immiscibility and water–rock interactions are considered to be the two main mechanisms of gold deposition. Due to the lack of large granite bodies exposed in this ore district, we infer that the fluids of gold deposit and quartz porphyry may have both been exsolved from a concealed granite pluton at deeper locations, and we further propose that Liyuan gold deposit is typical magmatic–hydrothermal gold deposits.

Formation of the Miaoan Au-Polymetallic Deposit in the Northern Taihang Mountain, North China Craton: Ore Geology, Geochronological and Geochemical Perspectives

“…However, these ratios will have a large range when hydrothermal activity is affected by metasomatism or other hydrothermal activities [82,83]. In this study, the Y/Ho values of pyrite (24.6-34.4) were similar to those of the mantle (25)(26)(27)(28)(29)(30), indicating the contribution of mantle materials. The Zr/Hf and Nb/Ta ratios of pyrite in the Miaoan Au deposit vary widely (19.4-243 and 4.38-70.0).…”

“…Studies in recent years have shown that the northern Taihang Mountain (TM), west of the NCC destruction zone, developed a large number of gold deposits, such as the Shihu, Yixingzhai, Liyuan, and Gengzhuang gold deposits (Figure 1a). However, these deposits have received relatively less attention [13,[24][25][26][27]. This is not conducive to understanding the genesis of Mesozoic gold deposits in the entire NCC destruction zone.…”

Genesis of the late‐stage base metal sulfide mineralisation and its relationship with the regional deformation in Ambaji–Deri, South Delhi Terrane, North‐West India

“…The presence of type 3a FI in the late‐stage indicates that at the culmination of the mineralisation, the ore fluid composition changes into the H 2 O‐NaCl dominant fluid. In addition, FI trapped during the late stage of mineralisation has low temperature and salinity because of the mixing of ore‐forming fluid with meteoric water, which indicated that the ore‐bearing fluids underwent cooling and dilution (Hedenquist & Henley, 1985; Lawrence et al, 2013; Pollard, 2006; Shepherd et al, 1985; Tan, Xia, Xie, & Yan, 2015; Ulrich, Guenther, & Heinrich, 2001; Wilkinson, 2001; Zhu et al, 2019). On the other hand, secondary inclusions were formed along the fracture that developed at the later stage of deformation at the end stage of crystallization of minerals.…”

“…Further, it shows that fluid immiscibility might be the major process from which the original aqueous gaseous (H 2 O‐NaCl‐CO 2 ± N 2 ) fluid separated into gaseous (CO 2 ± N 2 ) and saline aqueous fluid (H 2 O‐NaCl). (Pichavant, Ramboz, & Weisbrod, 1982; Zhu et al, 2019). Some inclusions homogenized at above 400°C have a slight variation in salinity, indicating the separation of moderately saline fluid from the granitic melt (Jackson, Willis‐Richards, Manning, & Sams, 1989; Shepherd et al, 1985) (Figure 11b).…”

Ore Genesis of the Changkeng–Fuwan Au-Ag Deposit in Central Guangdong, South China: Evidence from Fluid Inclusions and C-H-O-S-Pb-He-Ar Isotopes

“…The scanning range for the spectra lay between 100 and 4000 cm −1 , with an accumulation time of 10 s for each scan and a spectral resolution of 1-2 cm −1 . The detailed procedures followed those reported in previous studies [53][54][55][56].…”