Fig 4 - uploaded by Yaoqing Luo
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Field (a-b) and hand specimen (c) photographs showing typical wolframite-bearing quartz vein and greisenization in the AFG. The vein (8-21 cm in width, ~5 m in length) is not very straight, mainly comprising quartz, K-feldspar, muscovite, wolframite, and pyrite. Due to surface weathering, the pyrite was mostly oxidized to jarosite, displaying dark brown in the vein. The greisenization zone occurs close to the vein, having a width of 13-30 cm. On the left side of the quartz vein, the greisenization is weak, while the greisenization on the upper and lower sides is intense. Mineral abbreviations as in Fig. 3, plus Wolframite = Wol, Wolframite-bearing quartz vein = WQV.
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... fluid flow through the fractures in the apical part of the stock caused the formation of the quartz veins and greisenization. Many small-scale wolframite-bearing quartz veins and veinlets (WQV) occur in the AFG (Figs. 2b and 4). Ore minerals mainly include wolframite and pyrite (Fig. 4a), and gangue minerals are quartz, Kfeldspar, and muscovite. Greisenization commonly occurs close to these veins and veinlets (Fig. 4a). The GP close to the AFG was also partly greisenized ( Figs. 3c-d and 5d). According to Zou and Li (2006), the largest greisen layer is present in the AFG with 0.5-1.5 m in width and 13 m in length, ...
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... caused the formation of the quartz veins and greisenization. Many small-scale wolframite-bearing quartz veins and veinlets (WQV) occur in the AFG (Figs. 2b and 4). Ore minerals mainly include wolframite and pyrite (Fig. 4a), and gangue minerals are quartz, Kfeldspar, and muscovite. Greisenization commonly occurs close to these veins and veinlets (Fig. 4a). The GP close to the AFG was also partly greisenized ( Figs. 3c-d and 5d). According to Zou and Li (2006), the largest greisen layer is present in the AFG with 0.5-1.5 m in width and 13 m in length, consisting of gangue minerals of quartz and muscovite and minor ore minerals of wolframite, pyrite, beryl, topaz, and fluorite. As the ...
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... in the albite matrix (Fig. 6c-e), and the muscovite-fluorite assemblages only occur occasionally in albite (Figs. 5f and 6d-e). This evidence also indicates that the exsolved fluids are rich in F. The secondary muscovite in the WQV was crystallized from the exsolved fluids because the greisenization halos related to the vein could be observed (Fig. 4a). Additionally, as mentioned in section 5.1, the presence of typical spongy zircons in the GP also suggests that fluid exsolution had taken place during late-stage evolution (ESM2 Fig. ...
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... of fluxing compounds, that rare magmatic wolframites occur in nature ( Li et al., 2021). The lack of wolframite in the AFG also suggests that tungsten concentration in the melts did not become saturated via magmatic differentiation. In the field, we found wolframite occurred in the quartz veins, veinlets, and the associated greisenization zone (Fig. 4). Quartz veins and veinlets are the typical products of hydrothermal activity, and greisenization halos are the products of fluid-rock interaction (e.g., Wang et al., 2022). Therefore, analogous to the granite-hosted tungsten mineralization in Nanling Range, South China (e.g., Dajishan, Wu et al., 2017;Dahutang, Yin et al., ...
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... fluorine-bearing fluids could dissolve ten times the mass of W than F-free hydrothermal fluid ( Wang et al., 2021). Consequently, the accumulation of F in the late exsolved fluids is critical for the transportation and enrichment of tungsten. Furthermore, an exsolved F-and W-rich fluid can induce greisenization near the roof of the granitic stock (Fig. 4), causing the replacements of feldspar by quartz, muscovite, fluorite, and topaz (Breiter et al., 2017 2+ and Mn 2+ in the reduced fluid to form ...
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... fluid flow through the fractures in the apical part of the stock caused the formation of the quartz veins and greisenization. Many small-scale wolframite-bearing quartz veins and veinlets (WQV) occur in the AFG (Figs. 2b and 4). Ore minerals mainly include wolframite and pyrite (Fig. 4a), and gangue minerals are quartz, Kfeldspar, and muscovite. Greisenization commonly occurs close to these veins and veinlets (Fig. 4a). The GP close to the AFG was also partly greisenized ( Figs. 3c-d and 5d). According to Zou and Li (2006), the largest greisen layer is present in the AFG with 0.5-1.5 m in width and 13 m in length, ...
Context 7
... caused the formation of the quartz veins and greisenization. Many small-scale wolframite-bearing quartz veins and veinlets (WQV) occur in the AFG (Figs. 2b and 4). Ore minerals mainly include wolframite and pyrite (Fig. 4a), and gangue minerals are quartz, Kfeldspar, and muscovite. Greisenization commonly occurs close to these veins and veinlets (Fig. 4a). The GP close to the AFG was also partly greisenized ( Figs. 3c-d and 5d). According to Zou and Li (2006), the largest greisen layer is present in the AFG with 0.5-1.5 m in width and 13 m in length, consisting of gangue minerals of quartz and muscovite and minor ore minerals of wolframite, pyrite, beryl, topaz, and fluorite. As the ...
Context 8
... in the albite matrix (Fig. 6c-e), and the muscovite-fluorite assemblages only occur occasionally in albite (Figs. 5f and 6d-e). This evidence also indicates that the exsolved fluids are rich in F. The secondary muscovite in the WQV was crystallized from the exsolved fluids because the greisenization halos related to the vein could be observed (Fig. 4a). Additionally, as mentioned in section 5.1, the presence of typical spongy zircons in the GP also suggests that fluid exsolution had taken place during late-stage evolution (ESM2 Fig. ...
Context 9
... of fluxing compounds, that rare magmatic wolframites occur in nature ( Li et al., 2021). The lack of wolframite in the AFG also suggests that tungsten concentration in the melts did not become saturated via magmatic differentiation. In the field, we found wolframite occurred in the quartz veins, veinlets, and the associated greisenization zone (Fig. 4). Quartz veins and veinlets are the typical products of hydrothermal activity, and greisenization halos are the products of fluid-rock interaction (e.g., Wang et al., 2022). Therefore, analogous to the granite-hosted tungsten mineralization in Nanling Range, South China (e.g., Dajishan, Wu et al., 2017;Dahutang, Yin et al., ...
Context 10
... fluorine-bearing fluids could dissolve ten times the mass of W than F-free hydrothermal fluid ( Wang et al., 2021). Consequently, the accumulation of F in the late exsolved fluids is critical for the transportation and enrichment of tungsten. Furthermore, an exsolved F-and W-rich fluid can induce greisenization near the roof of the granitic stock (Fig. 4), causing the replacements of feldspar by quartz, muscovite, fluorite, and topaz (Breiter et al., 2017 2+ and Mn 2+ in the reduced fluid to form ...
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... Taken together, liquidus undercooling was most probably caused by the decreasing temperature during the internal evolution of the system, and the crystallization of the relatively sodic initial melt generated the aplitic and layered border zone instead of graphic texture. Moreover, the progressively increasing Li and Cs contents, and decreasing Fe and Mg contents and Na/Li ratios in beryl ( Fig. 6b-d, g-h and 7b-e), combined with linear variations of K/Rb ratios and concentrations of incompatible elements in microcline and muscovite from the granite to pegmatite (Wang, 2022), are consistent with the fractional crystallization mechanism for the granite-pegmatite system (Shearer et al., 1987;Roda-Robles et al., 2012;Hulsbosch et al., 2014;Luo et al., 2023), and further confirm the successive evolution from the granite to pegmatite. In the layered muscovite-quartz-albite zone at the border of the pegmatite, coarse grained to megacrystals of beryl mainly distribute in the type III layers and paragenetically co-exist with quartz and muscovite ( Fig. 3e-f), while relatively paucity in aplitic albite dominated type I and II layers, possibly reflect that crystallization of beryl was mainly in the locally aqueous fluid-rich pegmatitic melt. ...
The Arskartor Be-Nb-Mo deposit is the second largest Be deposit in the Chinese Altai, NW China, which hosts over 11,000 tons of BeO resource. The muscovite-albite granite and rare-metal pegmatite in the ore district are spatially and temporally coexisted and both are beryllium mineralized. The muscovite-albite granitic stock can be divided into a barren zone and a Be-mineralized zone, and five internal zones are distinguished in the pegmatite, namely, the layered muscovite-quartz-albite zone, muscovite-quartz-microcline zone, quartz core, beryl-muscovite-quartz zone, and fine-grained albite zone. Beryl as the dominant Be-bearing mineral mainly occurs in the Be-mineralized granite, layered muscovite-quartz-albite and beryl-muscovite-quartz zones of the pegmatite. Subhedral to euhedral beryl in the Be-mineralized granite is interstitial to or intergrown with rock-forming minerals. In contrast, beryl crystals in the pegmatite are coarser in grain size and more euhedral in shape, and mainly coexisted with coarse “booked” muscovite and blocky quartz. Concentrations of Li, Cs and Na/Li ratios of beryl are 184–760 ppm, 218–1996 ppm, and 2.13–21.3, respectively. The progressive variations of incompatible elements compositions and Na/Li ratios are consistent with the fractional crystallization mechanism of the granite-pegmatite system. Paragenesis and internal structure of beryl suggest nonequilibrium crystallization of a relatively incompatible elements and fluxes-enriched late granitic melt, generated the coarse-grained Be-mineralized granite. With the progressive enrichment of incompatible and fluxing elements and decreasing temperature, liquidus overcooling was achieved and generated the aplite and immediate zoned pegmatite that hosts abundant beryl. Moreover, the differentiating pegmatitic melt with varying amounts of aqueous fluids at different melt fractions, likely resulted in heterogeneous distribution of beryllium and subsequent variable amounts of beryl crystallization in different internal zones. The exsolution of aqueous fluids from the residual pegmatitic melt resulted in Mo-mineralization and related hydrothermal alteration. Consequently, both protracted fractional crystallization and subsolidus processes contributed the formation of the Arskartor granite-pegmatite system with Be-polymetallic mineralization.
