Genesis of the Late Jurassic Shizitou Mo deposit, South China: Evidences from fluid inclusion, H O isotope and Re Os geochronology

Ni, Pei; Wang, Guo-Guang; Cai, Yanyan; Zhu, Xiaomin; Yuan, Hui-Xiang; Bao, Hanyong; Ding, Jun‐Ying; Chen, Hui

doi:10.1016/j.oregeorev.2016.08.013

Cited by 27 publications

(18 citation statements)

References 61 publications

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“…Containing abundant CO 2 ‐H 2 O inclusions is a remarkable feature at Xishadegai, whereas brines are typically less common. This fluid inclusion assemblage shows characteristics of deposits formed from felsic magmas in deeper environments (Baker, ; Ni et al, ), being different from porphyry deposits formed in shallow environments where are lack of CO 2 (Baker, ; Ni, Wang, et al, ; Wang, Chen, Wang, & Wang, ; Wang, Zhang, & Li, ; Wang, Zhang, Liu, & Que, ; Zhang, Wang, & Liu, ).…”

Section: Discussionmentioning

confidence: 96%

“…Phase separation (immiscibility or boiling) is widely developed in geological systems, including immiscibility of basic and felsic magmas, magma and hydrothermal fluids, saline aqueous and CO 2 fluids, and boiling of aqueous fluids (Lecumberri‐Sanchez et al, ; Lu, ; Roedder, ; Ulrich et al, ; Wang, Zhou, et al, ; Zarasvandi et al, ). As an effective mechanism of ore deposition, it is involved in many magmatic‐related ore deposits, especially in porphyry–skarn polymetallic systems (Bodnar, ; Chi & Lu, ; Lu, , ; Ni et al, , , ; Roedder, ; Roedder & Bodnar, ; Stefanova et al, ; Wang, Zhang, et al, ; Zhang, Gu, Liu, et al, ). Immiscibility and boiling most likely happened in the Xishadegai deposit based on the criteria outlined by Roedder ().…”

Section: Discussionmentioning

confidence: 99%

“…China is among the largest Mo‐producing countries in the world (Fan et al, ; Zeng et al, ). The Mo deposits in China are spatially distributed over several metallogenic belts, including the southern and northern margins of the North China Craton (NCC), South China, Tibet Plateau, and Tianshan–Beishan districts (Fan et al, ; Ni, Pan, et al, ; Ni, Wang, et al, ). They are controlled by the Central Asian Orogenic Belt (CAOB), Circum Pacific Tectonic Belt, and Tethyan Tectonic Belt and thus are considered to be indicators of tectonic settings and associated evolutionary trends (Chen, Zhang, Wang, Pirajno, & Li, ; Fan et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Genesis of the Xishadegai Mo deposit in Inner Mongolia, North China: Constraints from geology, geochronology, fluid inclusion, and isotopic compositions

Zhang

Sun

et al. 2018

Geological Journal

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The Xishadegai Mo deposit is a medium‐sized deposit located in the northern margin of the North China Craton. The Mo mineralization is structurally controlled, and spatially and temporally related to the Xishadegai felsic intrusive rocks. Ore bodies mainly occur as quartz veins/veinlets in altered granitic rocks associated with potassic, phyllic, argillic, and fluorite alterations. The ore‐forming process can be divided into 3 stages: Stage I K‐feldspar‐quartz ± molybdenite, Stage II quartz‐pyrite‐molybdenite‐muscovite ± fluorite, and Stage III quartz‐fluorite ± muscovite. Four types of fluid inclusions were distinguished in smoky grey and dark grey quartz of the main‐ore stage (II), including two‐phase aqueous inclusions, CO2‐H2O inclusions, daughter mineral‐bearing multiphase inclusions, and minor vapour aqueous inclusions. The fluid inclusions in smoky grey and dark grey quartz are homogenized at temperatures of 195–350 °C and 191–291 °C, respectively, with calculated salinities of 3.9–11.1% NaCleq and 31.5–33.0% NaCleq, respectively. The ore‐forming fluids belong to a H2O‐CO2‐NaCl system characterized by abundant CO2, moderate to high temperature, and low to high salinity. The δ18OH2O and δD values of ore‐stage quartz vary from −0.2‰ to 0.9‰ and from −120‰ to −104‰, respectively, indicating that the ore‐forming fluids were evolved from magmatic water and gradually mixed with significant amounts of meteoric water. Sulphur and lead isotopic compositions indicate that the ore materials were mainly derived from magmatic sources. Zircon LA‐ICP‐MS U–Pb dating on the mineralized porphyritic moyite yielded a weighted mean age of 235.1 ± 2.0 Ma, corresponding to the Triassic postcollisional setting following the closure of the Paleo‐Asian Ocean between the Siberian Plate and the North China Craton. The εHf(t) values and TDM2 ages range from −15.0 to −12.8 and from 2.2 to 2.1 Ga, respectively, suggesting that the Xishadegai granite was mainly generated by melting of Paleoproterozoic crustal components. Collectively, evidence from geology, fluid inclusion, H‐O‐S‐Pb isotopes, and geochronology suggests that the Xishadegai deposit could be classified as a magmatic–hydrothermal vein Mo deposit. Phase separation (immiscibility and boiling) was the most likely mechanism for ore deposition.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genesis of the Xishadegai Mo deposit in Inner Mongolia, North China: Constraints from geology, geochronology, fluid inclusion, and isotopic compositions

Zhang

Sun

et al. 2018

Geological Journal

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“…() and Ni et al . (). Results of the H–O isotopic analyses obtained were normalized with the Vienna Standard Mean Ocean Water standards.…”

Section: Samples and Methodologymentioning

confidence: 97%

Nature and Genesis of the Xiaobeigou Fluorite Deposit, Inner Mongolia, Northeast China: Evidence from Fluid Inclusions and Stable Isotopes

et al. 2018

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The recently discovered Xiaobeigou fluorite deposit is situated in the southern part of the Southern Great Xing'an Range metallogenic belt. Fluorite-bearing veins are rather common over the whole area. So far, 11 mineralized veins have been delineated at the Xiaobeigou deposit. Orebodies of the deposit are mainly hosted in Permian and Jurassic volcano-sedimentary rocks. The orebodies in this mining district exhibit a well-developed vertical zonation: from top to bottom, the orebodies can be divided into upper, central, and lower zones. The central zone is the most important part for mining operations, and it shows lateral zonation of fluorite mineralization. Rare earth element (REE) contents of the investigated samples are relatively low (less than 30.2 ppm). Furthermore, the REE contents of the fluorite grains from early to late ore stages exhibit a decreasing trend. All the fluorite samples show no or slightly positive Eu anomalies. Three types of fluid inclusions (FIs) are distinguished in the quartz and fluorite samples, including pure-liquid single-phase (PL-type), liquid-rich two-phase (L-Type), and vapor-rich two-phase (V-type) FIs. The FIs hosted in early-stage quartz were homogenized at 159.5-260.7 C (mainly 160-240 C); their salinities range from 0.18 to 1.22 wt.% NaCl eqv. The FIs hosted in early-stage fluorite yield slightly lower homogenization temperatures of 144.4-266.8 C (peaking at 140-220 C), which correspond to salinities of 0.18-0.88 wt.% NaCl eqv. Homogenization temperatures and salinities for the late stage are 132.5-245.8 C (mainly 160-180 C) and 0.18-1.40 wt.% NaCl eqv., respectively. Laser Raman spectroscopy of FIs shows that both the vapor and liquid compositions of the inclusions are dominated by H 2 O. The H-O isotopic compositions at Xiaobeigou suggest that the ore-forming fluids are predominantly of meteoric water origin. The Xiaobeigou deposit can be classified as a typical low-temperature hydrothermal vein-type fluorite deposit. Combined with regional data, we infer that the fluorite mineralization occurred during the Late Mesozoic in an extensional setting.

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“…The fluid inclusions in quartz were used for analyses of the hydrogen isotopic compositions and carbon isotopic compositions. Samples were first degassed of labile volatiles by heating under vacuum at 150°C for 3 h. Then, water and carbon dioxide were released by heating the samples to approximately 500°C by means of an induction furnace [37], and the water and carbon dioxide were separated. The separated water was converted to hydrogen by passage of overheated zinc grains at 410°C, and the hydrogen isotopes were analyzed with a MAT 253 mass spectrometer [38].…”

Section: Fluid Inclusion Measurementsmentioning

confidence: 99%

Fluid Inclusions and H-O-C-S Isotopes of the Wushan Copper Polymetallic Deposit in the Suizao Area, Hubei Province: Implications for Ore Genesis

et al. 2019

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The Wushan copper polymetallic deposit is located in the Tongbai-Dabie orogenic belt in central China. Two small granitoid stocks (Donggushan and Xigushan) occur in the deposit, which is next to the largest Qijianfeng Granite Complex in the Suizao area. The mineralization of Wushan copper polymetallic deposit is mainly composed of ore-bearing quartz veins and quartz stockworks. Two hydrothermal stages are identified as the quartz-sulfide stage (early stage) and the barren quartz stage (late stage). A detailed petrographic study shows four types of fluid inclusions in quartz, including the aqueous fluid inclusions (L+V/V+L), the aqueous-carbonic fluid inclusions (L+V+CO2), the pure carbon dioxide fluid inclusions (pure CO2), and the daughter mineral-bearing multiphase fluid inclusions (S). The daughter mineral-bearing multiphase fluid inclusions (S) are further divided into three subclasses according to their different solid mineral assemblages, including (1) S1: L+V+Hal, (2) S2: L+V+CO2+S (chalcopyrite), and (3) S3: L+V+S (calcite, chalcopyrite, and hematite)±Hal. A laser Raman spectroscopic analysis shows that the main components of fluid inclusions are water and carbon dioxide. The solid minerals of the S-type fluid inclusions include halite, calcite, chalcopyrite, and hematite. The homogenization temperatures of fluid inclusions are 377 to 468°C for the early stage, with a salinity of 11.1 to 34.1 wt.% NaCl equivalent (11.1 to 17.4 wt.% NaCl equivalent and 28.4 to 34.1 wt.% NaCl equivalent, respectively) and an estimated pressure of 89 to 137 MPa. The homogenization temperatures of fluid inclusions in the late stage are 267 to 380°C with salinity of 7.0 to 12.1 wt.% NaCl equivalent and an estimated pressure of 46 to 115 MPa. Therefore, the temperature, salinity, and pressure of the fluid show a decreasing trend from the early to the late stage. In the early stage, the fluid is immiscible, which leads to the precipitation of sulfides. Pyrite shows a δ34S of approximately 0 (-1.8 to +3.4‰), and chalcopyrite also shows a similar δ34S of approximately 0 (+1.5 to +2.4‰), which indicates that the sulfur in the ore-forming fluid is mainly derived from deep-seated magma. Combined with C-H-O isotopic compositions, the initial ore-forming fluid is likely magmatic water, but with the addition of meteoric water in the late stage. By comparing with the typical characteristics of magmatic hydrothermal vein deposit and orogenic deposit related to shear zones, we suggest that the Wushan copper polymetallic deposit is most likely a magmatic hydrothermal vein deposit, which is of great significance for the further exploration work in the Wushan and surrounding areas. This new finding also fills the gap that no magmatic hydrothermal vein type Cu deposits have been found in the Suizao area or even in the Qinling-Dabie orogenic belt in central China.

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Genesis of the Late Jurassic Shizitou Mo deposit, South China: Evidences from fluid inclusion, H O isotope and Re Os geochronology

Cited by 27 publications

References 61 publications

Genesis of the Xishadegai Mo deposit in Inner Mongolia, North China: Constraints from geology, geochronology, fluid inclusion, and isotopic compositions

Genesis of the Xishadegai Mo deposit in Inner Mongolia, North China: Constraints from geology, geochronology, fluid inclusion, and isotopic compositions

Nature and Genesis of the Xiaobeigou Fluorite Deposit, Inner Mongolia, Northeast China: Evidence from Fluid Inclusions and Stable Isotopes

Fluid Inclusions and H-O-C-S Isotopes of the Wushan Copper Polymetallic Deposit in the Suizao Area, Hubei Province: Implications for Ore Genesis

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