Multiple fluids involved in granite-related W-Sn deposits from the world-class Jiangxi province (China)

Contrasting fluid behavior during two styles of greisen alteration leading to distinct wolframite mineralizations: The Echassières district (Massif Central, France)

“…Several studies, particularly in recent years, suggest that FI in gangue minerals may not provide the same data as those investigated in Sn-W ore minerals, particularly for quartz which shows systematically lower FI T h (e.g., Campbell and Panter 1990;Moura et al, 2014;Ni et al, 2015a;Legros et al, 2019). Nevertheless, in most of these studies, petrographic textures clearly show that the gangue minerals postdate the ore.…”

“…This affirmation is verified by LA-ICP-MS analyses of magmatic-related FI, which record high amounts of Fe and Mn, in addition to W (Audétat et al, 1998;Harlaux et al, 2017;Yang et al, 2019). Yokart et al (2003), Legros et al (2019) and Liu et al (2018) propose mixing between orthomagmatic and meteoric fluids as the cause for wolframite deposition, while Pan et al (2019) suggest an input of sedimentary fluids as instrumental in precipitating wolframite. Based on microthermometric data, Korges et al (2018) and Jiang et al (2019) propose that depressurization, triggering boiling of the fluid, is the main factor for formation of greisen alteration and simultaneous wolframite-bearing veins.…”

“…Nevertheless, each mineralizing event can be taken individually as an analogue of other wolframite deposits. An example is the Maoping deposit in China (Legros et al, 2019) where a topazification episode shows similar features to the first (F-rich) greisen episode that affected the La Bosse stockwork, both in terms of mineral assemblage (topaz, Fe-Li-micas, wolframite and cassiterite), and characteristics of topaz-hosted FI, i.e., relatively high T h (ca. 330-340°C), low salinity (ca.…”

Effects of pH and Salinity on the Hydrothermal Transport of Tungsten: Insights from In Situ Raman Spectroscopic Characterization of K2WO4-NaCl-HCl-CO2 Solutions at Temperatures up to 400°C

“…As shown in Fig. 10 of Legros et al [28], LA-ICP-MS analyses of fluid inclusions hosted in topazbearing mineral assemblages generally yield an elevated W concentration, compared with that for topaz-free mineral assemblages. Therefore, the presence of polymeric tungstate(s) can maintain the high concentration of W in hydrothermal fluids, favoring high-grade W mineralization.…”

“…Accordingly, our previous experimental investigations were also focused on moderately acidic to weakly alkaline solutions [10,11]. However, topaz has been reported to be in close association with W mineralization in some vein-type deposits, in addition to muscovite and K feldspar (e.g., [3,[26][27][28][29]). Thermodynamic calculation on the pH dependences of the speciation of aluminosilicates in hydrothermal fluids indicates that topaz remains stable at pH values significantly lower than that of the muscovite-K feldspar assemblage (Appendix A (available here)).…”