The Zhijiadi Ag-Pb-Zn deposit is located in the central North China Craton. Fluid inclusions (FIs) studies indicate three types of FIs, including aqueous, aqueous-carbonic, and daughter mineral-bearing multiphase inclusions. The daughter minerals in FIs are mainly composed of marcasite, chalcopyrite, calcite, and dolomite. Microthermometric data show that the homogenization temperature and salinity of FIs decrease gradually from early to late stages. Homogenization temperatures from early to main to late stages span from 244 to 334 ∘ C, from 164 to 298 ∘ C, and from 111 to 174 ∘ C, respectively, while their salinities are 4.0-9.9 wt.% NaCl equiv., 0.5-12.7 wt.% NaCl equiv., and 0.2-8.8 wt.% NaCl equiv., respectively. Trapping pressures drop from 203-299 MPa (the early stage) to 32-158 MPa (the main stage). The dropping of pressure and temperature and mixing and/or dilution of oreforming fluids result in the formation of ore deposit. Combined with C-O-S-Pb isotopic compositions, the initial ore-forming fluids and materials were likely derived from a magmatic system. As a whole, we proposed that this deposit belongs to medium-low temperature hydrothermal deposit related to volcanic and subvolcanic magmatism strictly controlled by the fault zones.

The Liyuan gold deposit is hosted within Archean basement metamorphic rocks and controlled by the NNE-trending faults in the central North China Craton. The ore-forming processes can be divided into three stages (early, middle, and late). Three types of primary fluid inclusions (FIs) are identified in the Liyuan, including pure carbonic, carbonic-aqueous, and aqueous inclusions. The primary FIs of three stages are mainly homogenized at temperatures of 318-408 ∘ C, 201-329 ∘ C, and 136-229 ∘ C, with salinities of 2.1-8.9, 0.5-12.4, and 0.4-6.3 wt.% NaCl equivalent, respectively. The main Au mineralization is related to the middle stage, and water-rock interaction caused rapid precipitation of gold in this stage. The initial ore-forming fluids were likely magmatic water or metamorphic fluid and mixed with meteoric water at later stages. Due to the lack of granite body at the present mining levels, we speculate that it was magmatic water that might have been exsolved from a concealed granite body at greater depth or it was metamorphic fluid that was directly transported from depth via deep faults. Based on all the available geological and geochemical evidence, we suggest that the Liyuan deposit belongs to orogenic gold deposit that located in the interior North China Craton.

The Chalukou giant Mo deposit in the Heilongjiang Province, northeastern China, is a porphyry deposit hosted in an intermediate-felsic complex surrounded by Mesozoic volcano-sedimentary rocks. The mineralization process is composed of four stages, including quartz + K-feldspar (Stage I), quartz + molybdenite (Stage II), pyrite + chalcopyrite + quartz ± other sulphides (Stage III) and carbonate ± fluorite ± quartz (Stage IV). The mineralization is generally associated with intense K-feldspar-, fluorite-, phyllic-and propylitic alteration. Primary fluid inclusions (FIs) in quartz include four compositional types, i.e. pure carbonic (PC-type), aqueous-carbonic (C-type), daughter mineral-bearing (S-type) and aqueous (W-type) inclusions. Halite, sylvite and hematite are recognized as the daughter minerals in Stage I S-type FIs, whereas molybdenite and chalcopyrite occur as daughter minerals in Stage II S-type FIs. High-salinity and high pressure (>220 MPa) FIs exist in Stage I quartz veins, characterized by homogenization through halite dissolution at temperatures of 324 to 517°C. The paucity of coexisting vapour-rich FIs with similar homogenization temperatures at this stage indicates that the initial S-type inclusions have directly exsolved from the magma rather than boiling off of a low-salinity vapour. Stage I quartz has captured the C-and W-type FIs, which have totally homogenized at 270-530°C with salinities of 1.6-17.0 wt.% NaCl equiv. At Stage II, the coexistence of all FI types were only observed at pressures of 150-218 MPa and temperatures of 352-375°C, with two salinity clusters of 0.9-16.6 wt.% NaCl equiv. and 37-56 wt.% NaCl equiv. Stage III quartz contains W-type FIs with homogenization temperatures of 158-365°C, salinities of 0.5-9.0 wt.% NaCl equiv., and minimum pressures of 12-116 MPa; whilst Stage IV fluorite or calcite only contains W-type FIs with homogenization temperatures of 121-287°C, salinities of 0.5-5.3 wt.% NaCl equiv., and minimum pressures of 10-98 MPa. The estimated trapping pressure from Stages II to III suggests an alternating lithostatic-hydrostatic fluid-system caused by fluid boiling. Ore fluids at the Chalukou Mo deposit may have been evolved from a CO 2 -rich, high-salinity, and high-oxygen fugacity (fO 2 ) magma system, to a CO 2 -poor, low-salinity, and low-fO 2 epithermal system. Two key points may have contributed to the formation of the Chalukou giant Mo deposit: The magmatic origin and fluid boiling that has resulted in decompression and rapid precipitation of metals.

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