Ore genesis of the Zhuxi supergiant W-Cu skarn polymetallic deposit, South China: Evidence from scheelite geochemistry

Sun, Keke; Chen, Bin; Deng, Jun

doi:10.1016/j.oregeorev.2019.02.017

Cited by 55 publications

(22 citation statements)

References 47 publications

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“…Recently, scheelite was identified in sulfide ores in the Qiaomaishan deposit [8], which is unusual in the MLYMB compared to other porphyry and skarn deposits. In contrast with the economically significant W-Cu deposits (e.g., Zhuxi and Dahutang) associated with granitoid in the Jiangnan Tungsten Belt [10][11][12], Cu-W mineralization in Qiaomaishan is negligible. However, mineralization of Cu-W is rare and uncommon in the MLYRB, making Qiaomaishan a significant example for investigating regional polymetal mineralization.…”

Section: Introductionmentioning

confidence: 88%

The Role of Magma Mixing in Generating Granodioritic Intrusions Related to Cu–W Mineralization: A Case Study from Qiaomaishan Deposit, Eastern China

Lu²,

Yang

et al. 2020

Minerals

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The newly exploited Qiaomaishan Cu−W deposit, located in the Xuancheng ore district in the MLYRB, is a middle-sized Cu-W skarn-type polymetallic deposit. As Cu-W mineralization is a rare and uncommon type in the Middle-Lower Yangtze River Belt (MLYRB), few studies have been carried out, and the geochemical characteristics and petrogenesis of Qiaomaishan intrusive rocks related to Cu-W mineralization are not well documented. We studied two types of ore-bearing intrusive rocks in the Qiaomaishan region, i.e., pure granodiorite porphyry and granodiorite porphyry with mafic microgranular enclaves (MMEs). Age characterization using zircon LA-ICP-MS showed that they were formed almost simultaneously, around 134.9 to 135.1 Ma. Granodiorite porphyries are high Mg# adakites, characterized by high-K calc-alkaline and metaluminous features that are enriched in LILEs (e.g., Sr and Ba) and LREEs, but depleted in HFSEs (e.g., Nb, Ta, and Ti) and HREEs. Moreover, they have enriched Sr-Nd-Hf isotopic compositions (with whole-rock ( 87 Sr/ 86 Sr) i ratios (0.706666−0.706714), negative ε Nd (t) values of −9.1 to −8.6, negative zircon ε Hf (t) values of −12.2 to −6.7, and two-stage Hf model ages (T DM 2) between 1.5 and 2.0 Ga). However, compared to host rocks, the granodiorite porphyry with MMEs shows variable geochemical compositions, e.g., high Mg#, Cr, Ni, and V contents and enriched with LILEs. In addition, they have more depleted I Sr , ε Nd (t), and ε Hf (t) values (0.706025 to 0.706269, −6.4 to −7.4, and −10.6 to −5.7, respectively), overlapping with regions of Early Cretaceous mafic rocks derived from enriched lithospheric mantle in the MLYRB. Coupled with significant disequilibrium textures and geochemical features of host rocks and MMEs, we propose that those rocks have resulted from mixing the felsic lower crust-derived magma and the mafic magma generated from the enriched mantle. The mixed magmas subsequently rose to shallow crust to form the ore-bearing rocks and facilitate Cu-W mineralization.

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Section: Introductionmentioning

confidence: 88%

The Role of Magma Mixing in Generating Granodioritic Intrusions Related to Cu–W Mineralization: A Case Study from Qiaomaishan Deposit, Eastern China

Lu²,

Yang

et al. 2020

Minerals

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“…This suggests that, in addition to the Mo content, the Cd content of scheelite can also be used to estimate the redox conditions of ore-forming fluids. [9], Xitian [38]; the reduced tungsten skarn deposits, including the Zhuxi [15], Xianglushan [14], Kyanigan [39].…”

Section: Oxidation State Of Ore-forming Fluidsmentioning

confidence: 99%

“…Consequently, this led to a disequilibrium between precipitated scheelite and evolving fluids [16,17]. In addition, the W contents of garnet from the Xiaoyao deposit are [9], Xitian [38]; the reduced tungsten skarn deposits, including the Zhuxi [15], Xianglushan [14], Kyanigan [39].…”

Section: Dissolution and Re-precipitationmentioning

confidence: 99%

“…The REE patterns in scheelite are highly sensitive to the hydrothermal evolution, making scheelite act as a promising tool to understand prevailing hydrothermal conditions [3,4]. Despite the extensive literature on trace elements in scheelite, only a few studies focus on tungsten skarn deposits [12][13][14][15]. Most tungsten skarn deposits are characterized by multiple scheelite generations which underwent dissolution and re-precipitation processes [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Geochemistry and Origin of Scheelites from the Xiaoyao Tungsten Skarn Deposit in the Jiangnan Tungsten Belt, SE China

Mao

Sun

et al. 2020

Minerals

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The type, association, variations, and valence states of several metal elements of scheelite can trace the source and evolution of the ore-forming fluids. There are four types of scheelite from the Xiaoyao deposit: (1) scheelite intergrown with garnet in the proximal zone (Sch1a) and with pyroxene in the distal zone (Sch1b), (2) scheelite replaced Sch1a (Sch2a) and crystallized as rims around Sch1b (Sch2b), (3) quartz vein scheelite with oscillatory zoning (Sch3), and 4) scheelite (Sch4) within micro-fractures of Sch3. Substitutions involving Mo and Cd are of particular relevance, and both elements are redox-sensitive and oxidized Sch1a, Sch2b, Sch3 are Mo and Cd enriched, relatively reduced Sch1b, Sch2a, Sch4 are depleted Mo and Cd. Sch1a, Sch2a, Sch3, and Sch4 are characterized by a typical right-inclined rare earth element (REE) pattern, inherited from ore-related granodiorite and modified by the precipitation of skarn minerals. Sch1b and Sch2b are characterized by low light rare earth element/heavy rare earth element (LREE/HREE) ratios, influenced by a shift in fO 2 during fluid-rock alteration. Sch1b, Sch2b and Sch3 have higher Sr contents than those of Sch1a and Sch2a, reveal that host-rock alteration and fluid-rock interaction have elevated Sr contents. The Y/Ho ratios of scheelite gradually increase from skarn to quartz vein stages, due to fluid fractionation caused by fluid-rock interaction. Thus, the variation in REE and trace elements in scheelite in time and space reflects a complex magmatic-hydrothermal process involving various fluid-rock interactions and fluid mixing.Minerals 2020, 10, 271 2 of 22 (CL) imaging has been proven to be an effective technique to reveal internal textures, zoning and trace element distributions in scheelite [3]. However, previous studies did not evaluate dissolution and re-precipitation processes in scheelite from tungsten skarn deposits due to the changing hydrothermal fluids [13,14]. The detailed textural characterization and systematic investigations of scheelite from each stage prior to in situ chemical analysis are critical to constraint the evolution of skarn systems and W ore precipitation.The Jiangnan tungsten belt in the southeastern margin of the Yangtze Craton is a new giant tungsten province with WO 3 reserves over 5.0 million tons [19][20][21][22][23], including the Dahutang (reserves of 1.10 Mt and grade of 0.18%) and the Zhuxi (reserves of 3.44 Mt and grade of 0.54%) deposits, as well as other large-scale tungsten deposits, such as Yangchuling, Xiaoyao, Dongyuan, Zhuxiling deposits [24][25][26]. The present study focuses on the Xiaoyao tungsten skarn deposit, characterized by complex scheelite textural features. The Xiaoyao deposit has reserves of 75,000 tons of WO 3 with an average grade of 0.2% [27]. We present both textural and compositional features for scheelite from the Xiaoyao deposit to evaluate the importance of dissolution and re-precipitation processes in the formation of skarn-related scheelite.

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“…Additionally, scheelite holds a reasonable amount of trace elements substituted in the Ca site. Due to this characteristic, scheelite can act as a useful geochemical environment tracer of the ore deposit [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Sequential Scheelite Mineralization of Quartz–Scheelite Veins at the Sangdong W-Deposit: Microtextural and Geochemical Approach

et al. 2020

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The Sangdong W (tungsten)-deposit is known as one of the world’s largest W-deposits, a magmatic–hydrothermal ore deposit including both skarn and hydrothermal alteration zones. The strata-bound characteristic of the deposit resulted in three major orebodies (hanging wall, main, footwall). The main ore mineral is a scheelite (CaWO4)–powellite (CaMoO4) solid solution. We examined the fluid evolution and scheelite formation process of the quartz–scheelite veins of the ore deposit, based on the microtextures and geochemical characteristics of the scheelite. After the initial magmatic–hydrothermal fluid release from the granitic body, prograde skarn is formed. In the later prograde stage, secondary fluid rises and precipitates stage I scheelite. Well-developed oscillatory zoning with the highest Mo content indicates continuous fluid infiltration under an open system. Pressure rises as mineralization occurs, generating the pressure release of the retrograde fluid. Fluid migrates downward by the gravitational backflow mechanism, forming stage II to IV scheelites. Dented oscillatory zoning of stage II scheelite is strong evidence of this pressure release. Stage III and IV scheelite do not show specific internal structures with pure scheelite composition. Retrograde scheelites are formed by fractional crystallization under a closed system. The observation of systematical fractional crystallization in the quartz–scheelite vein system is a meaningful result of our research. The geochemical characteristics and microtextural evidence imprinted in scheelites from each stage provide crucial evidence for the understanding of sequential scheelite mineralization of the quartz–scheelite vein system of the Sangdong W-deposit.

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Ore genesis of the Zhuxi supergiant W-Cu skarn polymetallic deposit, South China: Evidence from scheelite geochemistry

Cited by 55 publications

References 47 publications

The Role of Magma Mixing in Generating Granodioritic Intrusions Related to Cu–W Mineralization: A Case Study from Qiaomaishan Deposit, Eastern China

The Role of Magma Mixing in Generating Granodioritic Intrusions Related to Cu–W Mineralization: A Case Study from Qiaomaishan Deposit, Eastern China

Geochemistry and Origin of Scheelites from the Xiaoyao Tungsten Skarn Deposit in the Jiangnan Tungsten Belt, SE China

Sequential Scheelite Mineralization of Quartz–Scheelite Veins at the Sangdong W-Deposit: Microtextural and Geochemical Approach

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