The characteristics, origin, and significance of mafic microgranular enclaves in the granitoids from the <scp>B</scp>ailingshan complex, <scp>E</scp>astern <scp>T</scp>ianshan, <scp>NW C</scp>hina

Chen, Shue; Fan, Shuanghu; Yang, Lintao; Zhang, Yibin; Zhang, Li; Liu, Lei; TianYu, Zhang

doi:10.1002/gj.3232

Cited by 6 publications

(5 citation statements)

References 23 publications

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“…The loadings were 0.822, 0.816 and 0.719 for Zn, Cd and Pb, respectively. These three metals are commonly found together in various types of ore deposits [ 43 , 76 ]. The upper reaches of the Heihe River originates in the Qilian Mountains, which is in the Qilian metallogenic belt, one of the six grand metallogenic belts in the Tibetan Plateau.…”

Section: Resultsmentioning

confidence: 99%

Heavy Metals in Surface Soils in the Upper Reaches of the Heihe River, Northeastern Tibetan Plateau, China

Sun

Zhou

et al. 2016

IJERPH

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The upper reaches of the Heihe River have been regarded as a hotspot for phytoecology, climate change, water resources and hydrology studies. Due to the cold-arid climate, high elevation, remote location and poor traffic conditions, few studies focused on heavy metal contamination of soils have been conducted or reported in this region. In the present study, an investigation was performed to provide information regarding the concentration levels, sources, spatial distributions, and environmental risks of heavy metals in this area for the first time. Fifty-six surface soil samples collected from the study area were analyzed for Cr, Mn, Ni, Cu, Zn, As, Cd and Pb concentrations, as well as TOC levels. Basic statistics, concentration comparisons, correlation coefficient analysis and multivariate analyses coupled with spatial distributions were utilized to delineate the features and the sources of different heavy metals. Risk assessments, including geoaccumulation index, enrichment factor and potential ecological risk index, were also performed. The results indicate that the concentrations of heavy metals have been increasing since the 1990s. The mean values of each metal are all above the average background values in the Qinghai Province, Tibet, China and the world, except for that of Cr. Of special note is the concentration of Cd, which is extremely elevated compared with all background values. The distinguished ore-forming conditions and well-preserved, widely distributed limestones likely contribute to the high Cd concentration. Heavy metals in surface soils in the study area are primarily inherited from parent materials. Nonetheless, anthropogenic activities may have accelerated the process of weathering. Cd presents a high background concentration level and poses a severe environmental risk throughout the whole region. Soils in Yinda, Reshui daban, Kekeli and Zamasheng in particular pose threats to the health of the local population, as well as that of livestock and wildlife.

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Section: Resultsmentioning

confidence: 99%

Heavy Metals in Surface Soils in the Upper Reaches of the Heihe River, Northeastern Tibetan Plateau, China

Sun

Zhou

et al. 2016

IJERPH

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“…Recently, the granitoids in the study area have been considered as a component of the Bailingshan granitic complex (Zhao et al, 2019). Zircon U–Pb dating results have shown that they have emplaced at the age of 317–307 Ma (Chen et al, 2018; Fan et al, 2018; Zhang et al, 2016). Three sets of fault systems, mainly NE‐, E‐W‐, and NW‐trending, are developed in the deposit area (Jia & Zhao, 2017).…”

Section: Deposit Geologymentioning

confidence: 99%

Using titanite to constrain geochronology and physicochemical conditions of hydrothermal mineralization events: A case study of the Duotoushan Fe–Cu deposit, Eastern Tianshan, NW China

Zhang

Chen

2022

Geological Journal

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As a common Ca‐ and Ti‐ bearing silicate mineral in many types of hydrothermal deposits, titanite usually contains high concentrations of trace elements. Its mineral chemistry and U–Pb isotope can reveal the physicochemical conditions and geochronology of the ore‐forming systems. In this contribution, we present a detailed study on titanite which precipitated during the Fe mineralization in the Duotoushan deposit. Due to coexistence with hydrothermal minerals, low Th/U ratios (0.02–0.3), and depletion in rare earth elements (REE), all the studied titanites are classified into a hydrothermal group. The negative correlation between [REE3+ + (Al, Fe)3+] and [Ca2+ + Ti4+] indicates that REE mainly entered the lattice of titanite via the mechanism of substitution. In addition, titanite grains are characterized by HREE, Zr, and Nb enrichments with LREE depletion, suggesting that the complexation of F− at neutral to alkaline pH conditions may have caused the fractionation of REE. At Duotoushan, the titanite grains coexist with quartz, epidote, amphibole, and magnetite, and exhibit positive Eu anomalies (δEu = 1.04–1.31) but lack Ce anomalies, indicating that ore‐forming fluids may have been derived from a relatively low oxygen fugacity and high fH2O environment. Titanite yielded an in‐situ U–Pb lower‐intercept age of 307.2 ± 4.8 Ma (MSWD = 0.97), consistent with the syn‐ore amphibole 40Ar‐39Ar plateau age (305 ± 6 Ma). Since the mineralization ages are obviously younger than country rocks, the previous syn‐sedimentary ore‐forming model for Duotoushan Fe–Cu mineralization can be excluded. Integrating the characteristics from ore deposit geology, periods of mineralization events, and spatial–temporal distribution of magmatism, we proposed that the Duotoushan Fe–Cu mineralization event may be linked with a hidden granite in its orefield.

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“…Their vestiges typically occur as enclaves (e.g. pillows) and distended syn-plutonic dykes that exhibit visible evidence of magma mingling and limited evidence of mixing, resulting in rocks with intermediate compositions (Collins et al 2000;Chen et al 2018). As the granite solidifies beyond the particle locking threshold (~72-75% solidification, Vigneresse et al 1996), the latest mafic intrusions may be preserved as discrete syn-to late-plutonic dykes ranging from diabase to lamprophyre in composition.…”

Section: Conceptual Model For Coeval Appinite Suite and Granitoid Com...mentioning

confidence: 99%

“…However, most internal domains of batholiths preserve field evidence of interaction between coeval granitoid and mafic magmas, such as the presence of mafic enclaves (e.g. Vernon 1984; Barbarin and Didier 1992;Clarke et al 2000;Chen et al 2018), as well as petrographic and geochemical evidence for processes such as mingling and mixing, which can produce rocks of intermediate compositions (e.g. Chappell 1996;Tate et al 1997;Baxter and Feely 2002;Miller et al 2009;Muir et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Logan Medallist 7. Appinite Complexes, Granitoid Batholiths and Crustal Growth: A Conceptual Model

Murphy

Collins

Archibald

2022

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Appinite bodies are a suite of plutonic rocks, ranging from ultramafic to felsic in composition, that are characterized by idiomorphic hornblende as the dominant mafic mineral in all lithologies and by spectacularly diverse textures, including planar and linear magmatic fabrics, mafic pegmatites and widespread evidence of mingling between coeval mafic and felsic compositions. These features suggest crystallization from anomalously water-rich magma which, according to limited isotopic studies, has both mantle and meteoric components. Appinite bodies typically occur as small (~2 km diameter) complexes emplaced along the periphery of granitoid plutons and commonly adjacent to major deep crustal faults, which they preferentially exploit during their ascent. Several studies emphasize the relationship between intrusion of appinite, granitoid plutonism and termination of subduction. However, recent geochronological data suggest a more long-lived genetic relationship between appinite and granitoid magma generation and subduction.Appinite may represent aliquots of hydrous basaltic magma derived from variably fractionated mafic underplates that were originally emplaced during protracted subduction adjacent to the Moho, triggering generation of voluminous granitoid magma by partial melting in the overlying MASH zone. Hydrous mafic magma from this underplate may have ascended, accumulated, and differentiated at mid-to-upper crustal levels (ca. 3–6 kbar, 15 km depth) and crystallized under water-saturated conditions. The granitoid magma was emplaced in pulses when transient stresses activated favourably oriented structures which became conduits for magma transport. The ascent of late mafic magma, however, is impeded by the rheological barriers created by the structurally overlying granitoid magma bodies. Magma that forms appinite complexes evaded those rheological barriers because it preferentially exploited the deep crustal faults that bounded the plutonic system. In this scenario, appinite complexes may be a direct connection to the mafic underplate and so its most mafic components may provide insights into processes that generate granitoid batholiths and, more generally, into crustal growth in arc systems.

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The characteristics, origin, and significance of mafic microgranular enclaves in the granitoids from the Bailingshan complex, Eastern Tianshan, NW China

Cited by 6 publications

References 23 publications

Heavy Metals in Surface Soils in the Upper Reaches of the Heihe River, Northeastern Tibetan Plateau, China

Heavy Metals in Surface Soils in the Upper Reaches of the Heihe River, Northeastern Tibetan Plateau, China

Using titanite to constrain geochronology and physicochemical conditions of hydrothermal mineralization events: A case study of the Duotoushan Fe–Cu deposit, Eastern Tianshan, NW China

Logan Medallist 7. Appinite Complexes, Granitoid Batholiths and Crustal Growth: A Conceptual Model

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