Ore formation of the Dayakou emerald deposit (Southwest China) constrained by chemical and boron isotopic composition of tourmaline

Long, Zheng-Yu; Yu, Xiang; Zheng, Yuanchuan

doi:10.1016/j.oregeorev.2021.104208

Cited by 14 publications

(6 citation statements)

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Section: Comparison Of the Raman Spectra Of The Different Inclusions ...supporting

confidence: 92%

“…The results are consistent with previous studies that showed that the spinel in Tajikistan was produced in talc-kyanite rocks [3]. The mineral inclusions in gemstones can record the history of gemstone formation [40,41]. Black, slightly transparent to opaque massive rutile inclusions are commonly found in spinels from Tajikistan.…”

Section: Comparison Of the Raman Spectra Of The Different Inclusions ...supporting

confidence: 92%

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A Comparative Study of the Gemological Characteristics and Inclusions in Spinels from Myanmar and Tajikistan

Zhang

Zhu

2022

Crystals

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Currently, most of the popular spinels in the jewellery market come from Myanmar and Tajikistan. It is well known that provenance is one of the main factors affecting the value of a gemstone, and the geographic origin of a gemstone can be determined by examining its gemological and inclusion characteristics. This study systematically characterized the conventional gemology of spinels from Myanmar and Tajikistan and compared the inclusions in the spinels from these two countries by means of gemological microscopy and Raman spectroscopy. The results showed that most red and pink Myanmarese spinels were octahedral or contact twins, while Tajikistani spinels are slabbed or octahedral distorted crystals. Columnar zircon is frequently found in Tajikistani spinels but rare in Myanmarese spinels, appearing as tiny accessory inclusions. There are three types of carbonate inclusions (magnesite, dolomite, and calcite) in Myanmarese spinels, but Tajikistani spinels have only one (magnesite). In addition, spinels of different origins include special inclusions. Myanmarese spinels contain pyrite inclusions; Tajikistani spinels contain rutile and talc inclusions.

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Section: Comparison Of the Raman Spectra Of The Different Inclusions ...supporting

confidence: 92%

Section: Comparison Of the Raman Spectra Of The Different Inclusions ...supporting

confidence: 92%

A Comparative Study of the Gemological Characteristics and Inclusions in Spinels from Myanmar and Tajikistan

Zhang

Zhu

2022

Crystals

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“…The emeralds are interpreted to originate from the interaction of a magmatic fluid with the host rocks, similarly to what described for the W mineralization, but in that case the local mudstone hosted the significant amount of V [26]. While we do not have any clear evidence of interaction with the local mudstone in this study, we assume that the metal-rich magmatic fluid, during its ascent, encountered multiple rock formations, which may include the V-rich mudstones, before interacting with the limestone and forming the scheelite-rich skarn, similarly to process recently described at the Dayakou emerald deposit in Southwest China [64].…”

Section: Magmatic Origin and Fluid-rock Interactionsupporting

confidence: 67%

Formation of the Lened W-(Be) Skarn Deposit by Neutralization of a Magmatic Fluid—Evidence from H3BO3-Rich Fluids

et al. 2022

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Magmatic-hydrothermal systems, especially those causing the formation of tungsten deposits, may be enriched in boron, as is suggested by the presence of hydrothermal tourmaline. This study examines the boron and metal (including tungsten) concentrations of quartz-hosted fluid inclusions in the Lened W-(Be) deposit of the Canadian Cordillera and resolves (i) the analytical challenges involved during fluid salinity calculations of B-rich fluids and (ii) the relationship between fluid chemical composition and ore-forming processes involved at Lened. The aqueous fluid inclusions from this study have high CO2 and boron contents, indicated by the presence of a carbonic phase and sassolite crystals (H3BO3) in fluid inclusions. The boron content of the aqueous liquid phase (0.5 wt. %) was determined using microthermometric and Raman spectroscopic analyses. Boron was judged the most appropriate internal standard for quantifying the LA-ICP-MS data from these inclusions after calculation of salinity in the H2O-NaCl-H3BO3 system (3.5 to 5 wt. % NaCleq). Trace element data of the fluids show relatively high concentrations of Li (40 to 474 ppm), Al (56 to 1003 ppm), As (36 to 490 ppm) and Cs (68 to 296 ppm); and lower concentrations of Rb (3.6 to 77 ppm), Sr (0.4 to 23 ppm), Sb (1 to 32 ppm), Ba (0.6 to 163 ppm), Mg (6.9 to 7.6 ppm) and other metals, such as Be (2.4 to 10.2 ppm), W (2.4 to 27 ppm) and Cu (5.1 to 73 ppm). The high Cs and Li concentrations suggest a magmatic origin of the metals, while the moderate concentrations in Sr and Ba are indicative of fluid–rock interaction with the surrounding limestone. The presence of sassolite suggests that these fluids were highly acidic. The neutralization of this fluid through interaction with the surrounding limestone is the most probable trigger for scheelite precipitation. The presence of such high boron content in the magmatic fluid at Lened indicates the potential role in the enrichment of the source melt before fluid exsolution.

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“…Most of the in situ B isotopic compositions of tourmaline were measured at the GPMR using the same laser ablation system coupled to a Nu Plasma II multicollector ICP-MS. Additional analyses were conducted at the National Research Center for Geoanalysis, Chinese Academy of Geological Science (CAGS), using a Neptune Plus The analytical precision is estimated to be better than 0.5‰ (±2σ) based on the replicated analyses of reference tourmaline during this study. More detailed descriptions of the two analytical methods can be found in Zhao et al (2021a) and Long et al (2021), respectively. Ten replicated spots were arranged to monitor the analytical errors between the two labs, and the results showed near identical δ 11 B values between the two analyses (all less than 0.2‰, see details in Online Materials Table OM2).…”

Section: La-icp-ms and La-mc-icp-ms Analysismentioning

confidence: 99%

Tourmaline chemical and boron isotopic constraints on the magmatic-hydrothermal transition and rare-metal mineralization in alkali granitic systems

Wu,

Huang,

Zhang

et al. 2024

American Mineralogist

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The magmatic-hydrothermal transition in granite-related rare-metal metallogenic systems has received great attention, as economic rare metal (including rare earth) minerals reach saturation and trigger mineralization at this stage. However, deciphering the details of the melt-fluid evolution process and the distribution behavior of rare metals remains difficult. Here, we applied tourmaline chemistry and B isotopes to unravel processes at the magmatic-hydrothermal transition that are responsible for rare-metal partitioning in the Huoshibulake (HS) and Tamu (TM) REE-Nb-mineralized intrusions in Southern Tianshan, SW Central Asian Orogenic Belt. Three types of tourmaline are identified in the plutons: (1) disseminated tourmaline in the granite, with a brown-yellow core (HS-DB) and blue-green rim (HS-DG); ( 2) orbicular tourmaline, with a brown-yellow core (HS-OB and TM-OB) and blue-green rim (HS-OG and TM-OG); (3) vein tourmaline (HS-V and TM-V). Compositionally, all these tourmalines exhibit extremely low Ca and Mg contents and are classified as schorl. The substitution processes of major-element variations are dominantly caused by (Al, □) (Fe, Na) −1 exchange vectors. Four generations of tourmaline crystallization are established based on the petrographic, compositional, and B isotopes evolution of the tourmaline. Firstly, the HS-DB crystals crystallized from the highly evolved residual melt, and then HS-OB and TM-OB precipitated from immiscible B-rich aqueous melts during the magmatic-hydrothermal transition. Subsequently, the blue-green overgrowths (HS-DG, HS-OG, and TM-OG) crystallized from exsolved hydrothermal fluids. Finally, the formation of HS-V and TM-V resulted from another melt pulse from This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Ore formation of the Dayakou emerald deposit (Southwest China) constrained by chemical and boron isotopic composition of tourmaline

Cited by 14 publications

References 58 publications

A Comparative Study of the Gemological Characteristics and Inclusions in Spinels from Myanmar and Tajikistan

A Comparative Study of the Gemological Characteristics and Inclusions in Spinels from Myanmar and Tajikistan

Formation of the Lened W-(Be) Skarn Deposit by Neutralization of a Magmatic Fluid—Evidence from H3BO3-Rich Fluids

Tourmaline chemical and boron isotopic constraints on the magmatic-hydrothermal transition and rare-metal mineralization in alkali granitic systems

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