Compositions of biotite, amphibole, apatite and silicate melt inclusions from the Tongchang mine, Dexing porphyry deposit, SE China: Implications for the behavior of halogens in mineralized porphyry systems

Bao, Bo; Webster, James D.; Zhang, Dehui; Goldoff, B. A.; Zhang, Rongzhen

doi:10.1016/j.oregeorev.2016.05.024

Cited by 40 publications

(15 citation statements)

References 96 publications

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“…Based on analysis of the composition of the different types and stages of biotite and apatite, we can invert the changes in the physical and chemical conditions, such as the temperature, oxygen fugacity, and halogen fugacity, in the magmatic and hydrothermal stages (Bao et al, ; Jin et al, ; Li et al, ; Mao et al, ; Parsapoor et al, ; Smith, ; Xiao et al, ; Xing et al, ; Yuan et al, ; Zhang et al, ).…”

Section: Discussionmentioning

confidence: 99%

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

et al. 2019

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The trachyte-hosted Zhujiayuan deposit is located in the North Daba Mountain of South Qinling, China. In this deposit, the presence of different stages and genetic types of biotite, apatite, and rutile make it an excellent locality to constrain the mineralization process of Nb-REE in the alkaline igneous rock. In this study, supported by electron probe microanalyzer (EPMA), chemical analyses of biotite, apatite, rutile, columbite-group minerals, fersmite, monazite, and aeschynite-group minerals were presented. Three types of biotite were identified, including magmatic (Bt-1), reequilibrated (Bt-2), and hydrothermal biotite (Bt-3). Apatite can be divided into two types: magmatic (Ap-1) and hydrothermal apatite (Ap-2). Rutile can also be divided into two types: magmatic (Rt-1) and hydrothermal rutile (Rt-2). Rt-1 and Ap-1 contain average 1.44 wt% Nb 2 O 5 and 4.14 wt% LRE 2 O 3 , respectively, indicating that certain concentrations of Nb and REE were incorporated into the rutile and apatite, respectively, during the magmatic crystallization process. The distributions of the columbite-group, fersmite, monazite, and aeschynite-group minerals, as well as the compositional characteristics of monazite, indicate the important role of hydrothermal metasomatism during Nb-REE mineralization. The compositional characteristics of Bt-2 indicate relatively high F and Cl fugacities in the hydrothermal fluid. Bt-2 and Bt-3 both have higher Nb 2 O 5 content than Bt-1, indicating a higher Nb content in the fluid. The source of fluidic Nb likely derived from the metasomatism of magmatic rutile. The REE content decreased from Ap-1 to Ap-2, possibly due to a dissolutionreprecipitation process. The compositional changes from Bt-1 to Bt-3 and Ap-1 to Ap-2 also revealed a decrease in temperature, increase in oxygen fugacity, and increase in Ca content from the magmatic to the hydrothermal system. We speculate that rutile and apatite may have originally formed from an Nb-REE-rich alkalinesilicate melt derived from the metasomatized mantle, which led to the initial Nb-REE enrichment. Subsequent hydrothermal alteration by hydrothermal fluids rich in F and Cl, accompanied by changes in the above physical and chemical conditions and fluid composition, caused a relatively limited and localized remobilization of Nb-REE into the fractures and vesicles in the trachyte.

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Section: Discussionmentioning

confidence: 99%

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

et al. 2019

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“…Some studies have been performed on concentrations of volatiles that depend on the composition of the magma (e.g., Shabani et al 2003;De De Vivo et al 2005;Wallace 2005;Teiber et al 2014;Zellmer et al 2015;Bao et al 2016). Unfortunately, this information is lacking in the Variscan granitoids.…”

Section: Evolution Of CL and F Concentrations During Crystallization mentioning

confidence: 99%

“…% water (Whitney 1988). Furthermore, OH-bearing minerals (i.e., apatite, amphibole, biotite, and muscovite) can be commonly found in many magmatic rocks (e.g., Zhang et al 2012;Teiber et al 2014;Bao et al 2016). The second-most abundant volatile compound is CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Origin and evolution of volatiles in the Central Europe late Variscan granitoids, using the example of the Strzegom-Sobótka Massif, SW Poland

2018

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The results of the new Electron Microprobe Analysis of apatite, hornblende and biotite crystals of the hornblende-biotite variety of the Strzegom-Sobótka granite indicate that these rocks experienced several phases during their evolution. During the first phase, the melting of the continental crust was caused by heating from basaltic magma. Nevertheless, the system was closed, and there is no evidence of the influence of any mafic component. The volatile compositions of apatite crystals recorded the signature of this phase. Afterwards, small quantities of mafic material were delivered into the crystallizing melt by ascending basaltic magma. The volatile composition of hornblende, together with dramatic changes in the F/Cl ratios between apatite and hornblende, indicates that the injection of mafic material occurred between the crystallization of both minerals. During the crystallization of hornblende, the system was closed. During the last episode, the volatile composition recorded by biotite indicates that the system opened again. This is represented by the decrease of Cl in the melt. Moreover, the estimated F concentrations in the melt range from~2000 to~3000 ppm and do not change significantly within the crystallization interval, whereas the Cl concentrations decreased from 1470-900 ppm at 829-768°C to as low as 100 ppm at 710-650°C, most likely due to the continuous exsolution of aqueous fluid from silicate melt or the crystallization of Cl-bearing minerals.

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“…In addition, melt inclusions that might have preserved the volatile content at magmatic conditions are not always available (or large enough) within the crystal cargo of magmatic rocks. Nevertheless, common hydrous minerals such as biotite, amphibole and apatite may keep record of the evolution of various volatiles in the magma from which they crystallized (e.g., Coulson et al 2001;Parat et al 2011a;Zhang et al 2012Zhang et al , 2017Rasmussen and Mortensen 2013;Chambefort et al 2013;Van Hoose et al 2013;Teiber et al 2015;Scott et al 2015;Bao et al 2016).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

Chelle-Michou

Chiaradia

2017

Contrib Mineral Petrol

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Chlorine and sulfur are of paramount importance for supporting the transport and deposition of ore metals at magmatichydrothermal systems such as the Coroccohuayco Fe-Cu-Au porphyry-skarn deposit, Peru. Here, we used recent partitioning models to determine the Cl and S concentration of the melts from the Coroccohuayco magmatic suite using apatite and amphibole chemical analyses. The pre-mineralization gabbrodiorite complex hosts S-poor apatite, while the syn-and post-ore dacitic porphyries host S-rich apatite. Our apatite data on the Coroccohuayco magmatic suite are consistent with an increasing oxygen fugacity (from the gabbrodiorite complex to the porphyries) causing the dominant sulfur species to shift from S 2− to S 6+ at upper crustal pressure where the magmas were emplaced. We suggest that this change in sulfur speciation could have favored S degassing, rather than its sequestration in magmatic sulfides. Using available partitioning models for apatite from the porphyries, pre-degassing S melt concentration was 20-200 ppm. Estimates of absolute magmatic Cl concentrations using amphibole and apatite gave highly contrasting results. Cl melt concentrations obtained from apatite (0.60 wt% for the gabbrodiorite complex; 0.2-0.3 wt% for the porphyries) seems much more reasonable than those obtained from amphibole which are very low (0.37 wt% for the gabbrodiorite complex; 0.10 wt% for the porphyries). In turn, relative variations of the Cl melt concentrations obtained from amphibole during magma cooling are compatible with previous petrological constraints on the Coroccohuayco magmatic suite. This confirms that the gabbrodioritic magma was initially fluid undersaturated upon emplacement, and that magmatic fluid exsolution of the gabbrodiorite and the pluton rooting the porphyry stocks and dikes were emplaced and degassed at 100-200 MPa. Finally, mass balance constraints on S, Cu and Cl were used to estimate the minimum volume of magma required to form the Coroccohuayco deposit. These three estimates are remarkably consistent among each other (ca. 100 km 3 ) and suggest that the Cl melt concentration is at least as critical as that of Cu and S to form an economic mineralization.

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Compositions of biotite, amphibole, apatite and silicate melt inclusions from the Tongchang mine, Dexing porphyry deposit, SE China: Implications for the behavior of halogens in mineralized porphyry systems

Cited by 40 publications

References 96 publications

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

Mineralogical constraints on Nb–REE mineralization of the Zhujiayuan Nb (−REE) deposit in the North Daba Mountain, South Qinling, China

Origin and evolution of volatiles in the Central Europe late Variscan granitoids, using the example of the Strzegom-Sobótka Massif, SW Poland

Amphibole and apatite insights into the evolution and mass balance of Cl and S in magmas associated with porphyry copper deposits

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