Fluid Inclusions and C, H, O, S, and Pb Isotopic Compositions of the Dabaoshan Cu Polymetallic Deposit, Northern Guangdong Province, South China

2018 ◽  
Vol 68 (3) ◽  
pp. 258-274
Author(s):  
Hongying Qu ◽  
Jingwen Mao ◽  
Shumin Zhou
Keyword(s):  
Fluid Inclusions ◽  
South China ◽  
Guangdong Province ◽  
Polymetallic Deposit ◽  
Isotopic Compositions ◽  
Northern Guangdong

Constraints of fluid inclusions and C, O isotopic compositions on the origin of the dolomites in the Xisha Islands, South China Sea

2018 ◽  
Vol 493 ◽  
pp. 504-517 ◽  
Author(s):  
Dong-Jie Bi ◽  
Shi-Kui Zhai ◽  
Dao-Jun Zhang ◽  
Xiao-Feng Liu ◽  
Xin-Yu Liu ◽  
...  
Keyword(s):  
South China Sea ◽  
Fluid Inclusions ◽  
South China ◽  
Xisha Islands ◽  
China Sea ◽  
Isotopic Compositions

Re–Os dating of sulphides from the Yushui Cu-polymetallic deposit in eastern Guangdong Province, South China

2015 ◽  
Vol 70 ◽  
pp. 281-289 ◽  
Author(s):  
Yi Huang ◽  
Xiaoming Sun ◽  
Guiyong Shi ◽  
Rina Sa ◽  
Yao Guan ◽  
...  
Keyword(s):  
South China ◽  
Guangdong Province ◽  
Polymetallic Deposit

Well-Constrained Mineralization Ages by Integrated 40Ar/39Ar and U-Pb Dating Techniques for the Xitian W-Sn Polymetallic Deposit, South China

2021 ◽  
Author(s):  
Xiu-Juan Bai ◽  
Man Liu ◽  
Rong-Guo Hu ◽  
Yuan Fang ◽  
Xiao Liu ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
South China ◽  
Mineral Deposit ◽  
Mississippi Valley ◽  
Weighted Mean ◽  
Ore Formation ◽  
Polymetallic Deposit ◽  
Primary Fluid ◽  
Step Heating ◽  
Central South

Abstract Mineralization ages of many mineral deposit types (such as orogenic Au, stratabound Cu, and Mississippi Valley-type Pb-Zn deposits) are still difficult to date by the traditional isotopic chronometry because of the lack of suitable minerals. We have made efforts to establish a widely suitable dating technique to determine ore formation ages using a high-precision 40Ar/39Ar method on ubiquitously present fluid inclusions in quartz, sphalerite, and other nonpotassium minerals from hydrothermal deposits. The Xitian W-Sn polymetallic deposit in central South China contains several minerals suitable for isotopic dating for interchronometer comparison. 40Ar/39Ar laser step heating of 16 micas from ore veins, greisen, and metallogenic granites yields flat age spectra and thus well-defined ore formation ages ranging from 152.4 ± 1.5 (2σ) to 148.1 ± 1.4 Ma with an average of 150.2 ± 0.6 Ma. 40Ar/39Ar progressive crushing of nine quartz samples produces well-defined isochron lines for their primary fluid inclusions corresponding to isochron ages of 153.7–149.9 Ma with an average of 151.6 ± 0.6 Ma. Cassiterites from three hand specimens have weighted mean 206Pb/238U ages of 151.5 ± 1.7 (2σ), 149.7 ± 2.1, and 151.7 ± 2.1 Ma. All these new geochronological dates and previous molybdenite Re-Os ages yield well-constrained mineralization ages of 153–148 Ma for the Xitian W-Sn polymetallic deposit, which also confirms conclusively that the quartz 40Ar/39Ar progressive crushing technique is a feasible, valid dating technique. Furthermore, significant age information on the secondary fluid inclusions is potentially obtained simultaneously by this technique. We expect that this novel dating technique will be widely applied to determine the geologic fluids trapped in minerals during hydrothermal mineralization, hydrocarbon accumulation, metamorphism, tectonic activities, and other geologic processes.

scholarly journals Statistical Analysis of Mesovortices During The First Rainy Season In South China

2021 ◽  
Author(s):  
Ying Tang ◽  
Xin Xu ◽  
Yuanzhao Chen ◽  
Xunlai Chen ◽  
Jiahao Liang ◽  
...  
Keyword(s):  
South China ◽  
Rainy Season ◽  
Vertical Wind Shear ◽  
Guangdong Province ◽  
Statistical Characteristics ◽  
Pearl River Delta Region ◽  
Late Afternoon ◽  
Vapor Flux ◽  
Early Evening ◽  
Northern Guangdong

Abstract Based on the Doppler radar observation and reanalysis data, the statistical characteristics of mesovortices (MVs) during the first rainy season (April–June) in South China from 2017 to 2019 are studied, including their spatio-temporal distributions, structural features and favorable environmental conditions. The results show that the MVs usually exhibit short lifetime, among which about 70% last for less than 30 minutes. The intensity and horizontal scale of the MVs are proportional to their lifetime. Long-lived MVs have larger horizontal scales and stronger intensities than short-lived ones. The MVs are mainly observed over the Pearl River Delta region, followed by the western Guangdong province, but relatively fewer in both eastern and northern Guangdong province. The uneven spatial distribution of the MVs is closely related to the differences of environment conditions over South China. The monsoonal south-westerlies, water vapor flux, atmospheric instability and vertical wind shear over southwest Guangdong are significantly larger than those in other regions, which are favorable for the formation of MVs. The occurrence frequencies of MVs in central and southern parts of Guangdong display similar diurnal variations, reaching the peak during the late afternoon and early evening, while dropping to the minimum overnight. However, the situation is opposite in northern Guangdong, with the peak overnight and the minimum during the late afternoon and early evening.

scholarly journals Fluid Inclusions and H-O-C-S-Pb Isotope Studies of the Xinmin Cu-Au-Ag Polymetallic Deposit in the Qinzhou-Hangzhou Metallogenic Belt, South China: Constraints on Fluid Origin and Evolution

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Rui-Chun Duan ◽  
Shao-Yong Jiang
Keyword(s):  
High Temperature ◽  
Fluid Inclusions ◽  
South China ◽  
Late Stage ◽  
High Salinity ◽  
Main Stage ◽  
Pb Isotope ◽  
Isotope Data ◽  
Polymetallic Deposit ◽  
Metallogenic Belt

Qinzhou-Hangzhou metallogenic belt is an important polymetallic (Cu, Mo, W, Sn, Pb, Zn, Au, and Ag) belt in South China. The Xinmin polymetallic deposit is located in the southwestern segment of this belt, which ore bodies hosted in the contact zone of granite and Lower Devonian sedimentary strata and in the structure fractured zone within the strata. Three hydrothermal stages can be distinguished: quartz+tourmaline+pyrite (early stage), tourmaline+pyrite+galena+bismuthinite+sphalerite+chalcopyrite+pyrrhotite (main stage), and quartz+calcite+dolomite (late stage). The mineralizing fluid system can be described as aqueous with medium-high salinity (2.7-50.7 wt.‰ NaCl equiv. in the main stage and 0.18-8.81 wt.‰ NaCl equiv. in the late stage) and medium-high temperature of 485°C to 205°C (main stage) and 300°C to 116°C (late stage). The trapping pressures varied from 2 MPa to 30 MPa (main stage) and 0.4 MPa to 9 MPa (late stage). The δ 18 O values of quartz range from 6.7‰ to 8.5‰, and the δ D values for fluid inclusions in quartz range from -45‰ to -52‰. The calcite has C-isotopes ranging from -5.8‰ to +0.7‰ and O-isotopes from +12.7‰ to 21.4‰. H-O-C isotope data are consistent with a hydrothermal fluid derived from the Cretaceous granitoid magma. The δ 34 S values of sulfides are -3.3‰ to +1.9‰. Sulfides have 206Pb/204Pb ratios of 18.377 to 18.473, 207Pb/204Pb ratios of 15.606 to 16.684, and 208Pb/204Pb ratios of 38.613 to 38.902. The S-Pb isotope data suggest derivation of S and Pb mainly from the Cretaceous granitic magma. It is concluded that the Xinmin deposit is a medium-high temperature, medium-high salinity hydrothermal polymetallic deposit, related to the granitic magmatism and strictly controlled by the fault and shattered zones.

scholarly journals He-Ar Isotopes and Trace Gas Compositions of Fluid Inclusions in Massive Sulphides from the Yushui Copper-Polymetallic Deposit, South China: Metallogenic Implications

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 258
Author(s):  
Yi Huang ◽  
Zhongwei Wu ◽  
Xiaoming Sun ◽  
Yan Wang ◽  
Guiyong Shi ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
South China ◽  
Massive Sulphide ◽  
Trace Gas ◽  
Main Stage ◽  
Sulphide Deposit ◽  
Rock Interaction ◽  
Origin And Evolution ◽  
Polymetallic Deposit ◽  
Ore Bodies

The Yushui ore deposit, located in the middle section of the Yong’an-Meixian Hercynian depression, is a medium-sized Cu-polymetallic massive sulphide deposit in Eastern Guangdong Province, South China. This deposit is characterized by unusually high copper grade (up to 50–60 wt. % Cu). Other metallic elements, such as lead, zinc and silver, are also economically important in the Yushui ore bodies. The aim of this study was to apply N2–Ar–He systematics, together with organic gases (light-hydrocarbon tracers), to constrain the origin and evolution of ore-forming fluids. The helium-argon isotopes and trace gas compositions of fluid inclusions trapped within metal sulphide minerals were measured for a number of bonanza ores from the Yushui deposit. The noble gas concentrations in the studied samples vary over one to two orders of magnitude (4He: 2.27–160.00 × 10−5 cm3 STP g−1; 3He: 0.53–34.88 × 10−12 cm3 STP g−1; 40Ar: 6.28–37.82 × 10−7 cm3 STP g−1; 36Ar: 1.25–10.40 × 10−9 cm3 STP g−1). Our data show a narrow range of 3He/4He ratios from 0.006 to 0.056 Ra (~0.026 Ra on average, n = 8), which are considerably lower than the modern atmospheric end-member value; whereas the 40Ar/36Ar ratios (ranging from 333.76 to 501.68, with an average of 397.53) are significantly greater than that of air-saturated water. Most of the bornite samples have somewhat higher 3He/4He ratios of trapped fluids when compared to chalcopyrite. Overall, these He-Ar results are well within the range of crustal reservoir, thus implying a predominantly crustal source (originated from Caledonian basement) for ore-forming solutions, with little contribution from mantle-derived fluids. Analysis of the N2–Ar–He composition in Cu-rich sulphides indicates that the Yushui ore-forming fluids were probably derived from formation water (or basinal hot brines). Moreover, organic gas species identified in sulphide-hosted fluid inclusions are mainly composed of C1–C4 alkanes, while the concentrations of unsaturated olefins and aromatic hydrocarbons are very low. In particular, most chalcopyrite samples with relatively low 3He/4He ratios (0.006–0.016 Ra) and 40Ar*/4He values (0.0002–0.0012) are generally characterized by very high CO2/CH4 ratios (~60–102). All these suggest that main-stage Cu-Ag metallogenic processes might have not been affected by high-temperature magmatic activities or superimposed by strong metamorphic overprinting, although some chalcopyrite-rich ores appear to be influenced by later stage hydrothermal processes. In summary, neither magmatic input nor convecting seawater has played an important role in the formation of Yushui copper-polymetallic deposit. The massive sulphide ore bodies were products of water–rock interaction between metal-bearing basinal brines and the host sedimentary strata.

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