Fluid inclusion and stable isotope studies at the Chicote tungsten deposit, Bolivia

Thorn, Peter

doi:10.2113/gsecongeo.83.1.62

Cited by 21 publications

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“…However, the fluid inclusion data and the open space-filing type of deposition in large subhorizontal veins indicate very shallow depths of mineralization (600 to 1,300 m below the groundwater table existing during mineralization) and, thus, the likely involvement of meteoric water. At the other extreme, ore fluids for the Chicote tungsten vein deposit of the Bolivian tin belt appears to have been entirely of magmatic source (Thorn 1988). Higgins (1985) attributed wolframite deposition in the Grey River prospect, Newfoundland (Canada) to progressive CO 2 loss from the hydrothermal fluid by immiscibility and retrograde boiling; a similar mechanism might have been responsible for W-Sn deposition at Panasqueira.…”

Section: Panasqueira W-sn Vein Deposit Portugalmentioning

confidence: 99%

Understanding Mineral Deposits

Misra¹

2000

103

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Section: Panasqueira W-sn Vein Deposit Portugalmentioning

confidence: 99%

Understanding Mineral Deposits

Misra¹

2000

103

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“…This feature is distinct from that of typical magmatic deposits, for example, porphyry or IOCG deposits that have high‐temperature and high‐saline ore‐forming fluids directly derived from magma, such as the porphyry deposit at Bingham, Utah (Roedder, ) and IOCG deposits in the Cloncurry district, Queensland (Williams et al, ). This feature is also different from that of most granite‐related tungsten‐tin and gold deposits, for which the presence of high‐salinity fluids are common (e.g., Wilkinson, ; Baker, ), for example, the Chicote tungsten deposit in Bolivia (Thorn, ), the intrusion‐related Telfer gold‐copper deposit in Western Australia (Schindler et al, ), the San Rafael tin‐copper deposit in Southeast Peru (Wagner et al, ), as well as the gold deposit in Milk Lake area, Canada (Baker & Lang, ). Nevertheless, the ore fluid features are similar to those of ore fluid reported from orogenic gold deposit (e.g., Groves et al, ; Ridley & Diamond, ; Wille & Klemd, ).…”

Section: Discussionmentioning

confidence: 84%

Fluid Inclusions and Stable Isotopic Characteristics of the Yaoling Tungsten Deposit in South China: Metallogenetic Constraints

et al. 2018

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The Yaoling tungsten deposit is a typical wolframite quartz vein-type tungsten deposit in the South China metallogenic province. The wolframite-bearing quartz veins mainly occur in Cambrian to Ordovician host rocks or in Mesozoic granitic rocks and are controlled by the west-north-west trending extensional faults. The ore mineralization mainly comprises wolframite and variable amounts of molybdenite, chalcopyrite, pyrite, fluorite, and tourmaline. Hydrothermal alteration is well developed at the Yaoling tungsten deposit, including greisenization, silicification, fluoritization, and tourmalinization. Three types of primary/pseudosecondary fluid inclusions have been identified in vein quartz, which is intimately intergrown with wolframite. These include two-phase liquid-rich aqueous inclusions (type I), two-or three-phase CO 2 -rich inclusions (type II), and type III daughter mineral-bearing multiphase high-salinity aqueous inclusions. Microthermometric measurements reveal consistent moderate homogenization temperatures (peak values from 200 to 280 C), and low to high salinities (1.3-39 wt % NaCl equiv.) for the type I, type II, and type III inclusions, where the CO 2 -rich type II inclusions display trace amounts of CH 4 and N 2 . The ore-forming fluids are far more saline than those of other tungsten deposits reported in South China. The estimated maximum trapping pressure of the ore-forming fluids is about 1230-1760 bar, corresponding to a lithostatic depth of 4.0-5.8 km. The δD H2O isotopic compositions of the inclusion fluid ranges from −66.7 to −47.8‰, with δ 18 O H2O values between 1.63 and 4.17‰, δ 13 C values of −6.5-0.8‰, and δ 34 S values between −1.98 and 1.92‰, with an average of −0.07‰. The stable isotope data imply that the ore-forming fluids of the Yaoling tungsten deposit were mainly derived from crustal magmatic fluids with some involvement of meteoric water. Fluid immiscibility and fluid-rock interaction are thought to have been the main mechanisms for tungsten precipitation at Yaoling.

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“…The H and O isotopes of fluid inclusions are effective means to trace the contribution of ore-forming fluids from different sources (Ohmoto and Rye, 1970;Rye et al, 1974;Taylor, 1974). Previous studies, such as at Pato Buena in Peru (Landis and Rye, 1974), Panasqueira in Portugal (Kelly and Rye, 1979), Grey River in Canada (Higgins, 1985) and Chicote in Bolivia (Thorn, 1988), have shown that the main ore-forming fluids of wolframite -quartz vein-type deposits are magmatic in origin (Landis and Rye, 1974;Higgins, 1985;Thorn, 1988). In the late stage, such as at Jungbo, Suri and Deogma in South Korea (So and Yun, 1994), and Xihuashan, Dangping and Dajishan in Nanling , different degrees of atmospheric water-mixing are often recorded Shelton et al, 1987;So and Yun, 1994;Beuchat et al, 2004;Wei et al, 2012).…”

Section: Sources Of Ore-forming Fluidsmentioning

confidence: 99%

Ore‐forming Fluid and Metallogenic Mechanism of Wolframite–Quartz Vein‐type Tungsten Deposits in South China

Pan

2020

Acta Geologica Sinica (Eng)

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South China is endowed with copious wolframite–quartz vein‐type W deposits that provide a significant contribution to the world's tungsten production. Mineralization is spatially associated with highly evolved granites, which have been interpreted as products of ancient crustal anatexis. Ore veins are mainly hosted in low‐grade metamorphosed quartz sandstone, slate and granitic rocks. The ore minerals mainly comprise wolframite, cassiterite, scheelite and pyrite, with minor molybdenite, arsenopyrite and chalcopyrite. Typical steeply dipping veins can be divided into five zones from top to the bottom, namely: (I) thread, (II) veinlet, (III) moderate vein, (IV) thick vein, and (V) thin out zones. In general, three types of fluid inclusions at room temperature are commonly recognized in wolframite and/or quartz from these veins: two‐phase liquid‐rich (type L), two‐phase CO2‐bearing (type CB), and CO2‐rich (type C). Comparative microthermometry performed on fluid inclusions hosted in wolframite and associated quartz indicates that most wolframite was not co‐precipitated with the coexisting quartz. Detailed petrographic observation and cathodoluminescence (CL) imaging on coexisting wolframite and quartz of the Yaogangxian deposit, show repeated precipitation of quartz, wolframite, and muscovite, suggesting a more complex fluid process forming these veins. Previous studies of H‐O isotopes and fluid inclusions suggested that the main ore‐forming fluids forming the wolframite–quartz vein‐type deposits had a magmatic source, whereas an unresolved debate is centered on whether mantle material supplemented the ore‐forming fluids. The variable CO2 contents in the ore‐forming fluids also implies that CO2 might have had a positive effect on ore formation. Fluid inclusion studies indicate that wolframite was most likely deposited during cooling from an initial H2O + NaCl ± CO2 magmatic fluid. In addition, fluid‐phase separation and/or mixing with sedimentary fluid might also have played an important role in promoting wolframite deposition. We speculate that these processes determine the precipitation of W to varying degrees whereas the leading mechanistic cause remains an open question. Comprehensive studies on spatial variation of fluid inclusions show that both the steeply and gently dipping veins are consistent with the “five floors” model that may have broader applications to exploration of wolframite–quartz vein‐type deposits. Recent quantitative analysis of wolframite‐ and quartz‐hosted fluid inclusions by laser ablation inductively‐coupled plasma mass spectrometry shows enhanced advantages in revealing fluid evolution, tracing the fluid source and dissecting the ore precipitation process. Further studies on wolframite–quartz vein‐type W deposits to bring a deeper understanding on ore‐forming fluids and the metallogenic mechanism involved.

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Fluid inclusion and stable isotope studies at the Chicote tungsten deposit, Bolivia

Cited by 21 publications

References 0 publications

Understanding Mineral Deposits

Understanding Mineral Deposits

Fluid Inclusions and Stable Isotopic Characteristics of the Yaoling Tungsten Deposit in South China: Metallogenetic Constraints

Ore‐forming Fluid and Metallogenic Mechanism of Wolframite–Quartz Vein‐type Tungsten Deposits in South China

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