Preliminary study on light hydrocarbons in ore-forming fluids of gold and antimony deposits in southwestern Guizhou, China

Zhuang, Hanping; Lu, Jiqing; Fu, Jiamo; Liu, Jinzhong; Jixi, Shi

doi:10.1007/bf02882672

Cited by 6 publications

(5 citation statements)

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“…shows that the gaseous phase is composed mainly of light hydrocarbons, out of which methane, ethane and propane constitute 87.5%, 6.2%, and 2.5% of the total respectively (Zhuang et al, 1997). This suggests that the organic matter in the fluid is over matured, which is consistent with the homogenization temperature determination of the fluid inclusions.…”

Section: Organic Matter In the Host Rocks And Oressupporting

confidence: 79%

“…Pyrobitumen veins cut by late stage quartz veins were observed (Fig.5-lf-h). The reflectances of the vitrinites and pyrobitumens in the samples were not determined for this study; however, former work shows that the vitrinite reflectances range from 1.19% to 2.93% with an average value of 2.32%, while the reflectances of the pyrobitumen range from 2.84% to 3.90% with an average value of 3.24% (Zhuang et al, 1997). The reflectances of the pyrobitumens ( R^ ) are always higher than the corresponding vitrinite (Rv)-The reflectance of the vitrinite corresponds to a maximum paleo-temperature of 210~329°C (Price, 1983).…”

Section: Organic Matter In the Host Rocks And Oresmentioning

confidence: 94%

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Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China /

Bao¹

2001

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Section: Organic Matter In the Host Rocks And Oressupporting

confidence: 79%

Section: Organic Matter In the Host Rocks And Oresmentioning

confidence: 94%

Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China /

Bao¹

2001

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“…Ore-forming fluids of sediment-hosted, stratabound massive sulphide deposits, especially formation water or sedimentary basinal brines, usually contain a large amount of organic matters. The organic matters are principally composed of light hydrocarbon gases because most of liquid hydrocarbons are unstable at (medium to high) ore-forming temperatures [60]. It has been proposed that light hydrocarbons in crustal fluids were mainly generated by thermal cracking of kerogens caused by interactions between crustal fluids and organic matters in sedimentary rocks [57][58][59].…”

Section: Compositions Of Light Hydrocarbon Gasesmentioning

confidence: 99%

“…Additionally, quantitative bulk sample analysis of the ratios among conservative trace gas species N 2 , Ar, and He can help to estimate the amounts of magmatic, crustal and meteoric gaseous constituents in geothermal fluids [48][49][50][51][52][53][54][55]. Moreover, the concentrations and distribution features of light organic compounds (LOC, including methane) in fluid inclusions from a variety of hydrothermal systems or massive sulphide deposits can also serve as an important and powerful tool to interpret the various sources of organic species, as well as to illustrate fluid boiling/mixing processes, and provide useful information about the intensity of wall-rock alterations [56][57][58][59][60][61][62][63][64][65][66]. Therefore, an integrated study of the He-Ar isotopic systematics, combined with the N 2 -Ar-He or CH 4 /CO 2 ratios of fluid inclusion volatiles, allows us to further develop our understanding of fluid evolution and metallogenic processes in the Yushui copper-polymetallic ore deposit, South China.…”

Section: Introductionmentioning

confidence: 99%

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

Huang¹,

Sun

et al. 2019

Minerals

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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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“…Superficial Au resources (<500 m) in the Youjiang Basin have been gradually exhausted by extensive exploitation, necessitating urgent new prospecting methods to explore deep or concealed orebodies. Traditionally, the drilling targets of Carlintype Au deposits in the Youjiang Basin have been identified by delineating geochemical anomalies [8][9][10][11][12], relying on an understanding of the deep tectonic framework obtained from geophysical surveys [13][14][15]. Geochemical anomalies primarily depend on the content of ore-related elements, such as Au, As, Sb, Hg, and Tl.…”

Section: Introductionmentioning

confidence: 99%

Exploration Vectors and Indicators Extracted by Factor Analysis and Association Rule Algorithms at the Lintan Carlin-Type Gold Deposit, Youjiang Basin, China

Wang,

Cao,

Tan

et al. 2024

Minerals

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The Youjiang Basin in China is the world’s second-largest concentrated area of Carlin-type Au deposits after Nevada, USA, boasting cumulative Au reserves nearing 1000 t. This study examined the recently unearthed Lintan Carlin-type Au deposit within the Youjiang Basin. Factor analysis and association rule algorithms were used to identify exploration vectors and indicators essential for navigating this promising geological territory. In the Lintan mining area, the geological strata encompass the Triassic Bianyang, Niluo, and Xuman formations comprised clastic rocks, followed by the deeper Permian Wujiaping Formation with massive carbonate rocks. The orebodies are restricted to the F14 inverse fault, cutting through the Xuman Formation, with an additional F7 fault between the Wujiaping and Xuman formations. A total of 125 rock samples from the F14 fault and a representative cross-section were analyzed for 15 elements (Au, Ag, As, Bi, Cd, Co, Cu, Hg, Mo, Ni, Pb, Sb, Tl, W, and Zn). The elements were divided into four groups based on cluster and factor analysis. Group 1 (Co, Cu, Zn, Ni, Tl, W, and Bi) was mainly enriched in the Xuman, Niluo, and Bianyang formations controlled by sedimentary diagenesis. Group 2 (Au, As, Hg, and Sb) was concentrated in the F14 and F7 faults, representing Au mineralization. Group 3 (Pb, Ag, and Mo) was mostly enriched near the F14 and F7 faults, displaying a peripheral halo of Au mineralization, and was probability controlled by ore-forming hydrothermal activities. Group 4 (Cd and Mo) exhibited extreme enrichment along the periphery of the F7 fault. This pattern indicates the presence of a substantial hydrothermal alteration zone surrounding the fault, likely influenced by ore-forming hydrothermal processes. Additionally, Pb, Ag, Cd, Mo, and W are considered essential indicators for ore formation besides Au, As, Sb, Hg, and Tl. Twelve effective association rules were derived using the association rule algorithm, which can aid in discriminating Au mineralization. The spatial distributions of the 15 elements indicated that the F14 fault is the main ore-bearing fracture zone, while the F7 fault serves as the ore-conducting structure, channeling ore-forming fluids into the F14 fault. Faults between the Wujiaping and Xuman formations, along with their associated reverse faults, present potential prospecting targets both within and outside the Lintan Au deposit in the Youjiang Basin. Exploration geochemical data can be fully utilized by combining factor analysis and association rule algorithms, offering key guidance for prospecting Carlin-type gold and similar deposits.

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Preliminary study on light hydrocarbons in ore-forming fluids of gold and antimony deposits in southwestern Guizhou, China

Cited by 6 publications

References 0 publications

Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China /

Geochemistry of the sediment-hosted disseminated gold deposits in Southwestern Guizhou Province, China /

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

Exploration Vectors and Indicators Extracted by Factor Analysis and Association Rule Algorithms at the Lintan Carlin-Type Gold Deposit, Youjiang Basin, China

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