Genesis of the Heiyanshan Tungsten Skarn Deposit in the East Tianshan, NW China: Insights From Geology, Fluid Inclusion, Isotopic Geochemistry and Geochronology

The eastern Tianshan Terrane is a highly prospective zone that contains several porphyry Cu–Mo, VMS Cu–Zn, magmatic Cu–Ni, epithermal and orogenic Au deposits. However, few attention has been paid to tungsten deposits. Of these, the source and evolution of the mineralising fluids related to the skarn W deposits are poorly understood. The Heiyanshan W deposit is hosted by metamorphosed clastic and carbonate beds in the Mesoproterozoic Jianshanzi Formation deposited on a continental margin tectonic setting. The Jianshanzi Formation is intruded by biotite monzogranite that yield weighted 206Pb/238U age of 326.9 ± 1.6 Ma, which suggest that the Heiyanshan W deposit was formed in the Carboniferous. The mineralisation is hosted by a prograde hydrothermal altered zone represented by a garnet (–pyroxene) skarn, and retrograde skarn characterised by fine-grained scheelite. The paragenesis of the Heiyanshan mineralisation can be subdivided into prograde skarn stage, retrograde skarn stage, quartz-sulphide stage and quartz-calcite vein stage. The types of fluid inclusions recognised in the various minerals in the deposits are liquid-rich aqueous, vapour-rich aqueous, and daughter mineral-bearing. The homogenisation temperatures of fluid inclusions from the Heiyanshan deposit decrease from 290 ± 28°C in garnet, through 232 ± 31°C in scheelite, to 232 ± 36°C in quartz and 158 ± 15°C in non-mineralised calcite, which is typical of W-bearing skarn deposits worldwide. The δ18Owater values from the Heiyanshan deposit range from +4.7 to +6.6‰ in garnet, +1.3 to +1.9‰ in quartz and −6.1 to −4.4‰ in calcite. We have measured δD in fluid inclusions from different minerals, although these bulk analyses are just a mixture of the different FIA’s present in the sample. The δD values of fluid inclusions in garnet, quartz, and calcite are from −121 to −71‰, −84 to −75‰ and −101 to −82‰, respectively, also indicative of deep-sourced magmatic fluids mixed with meteoric water. The decrease in the homogenisation temperatures for the fluid inclusions at the Heiyanshan deposit is accompanied by a drop in salinity indicating that tungsten-bearing minerals precipitated during fluid mixing between magmatic fluids and meteoric water. We conclude that eastern Tianshan Terrane contains two pulse of tungsten metallogenic events of Late Carboniferous and Early Triassic.

Petrogeochemical and isotopic characteristics, connection with magmatism of tungsten deposits of Aginskaya and Argunskaya structural-formation zones of the Eastern Transbaikalia

Research subject. Tungsten deposits of the Aginsky and Argunsky structural-formation zones in the Eastern Transbaikalia. The aim was to clarify the sources and conditions for the formation of tungsten mineralisation, as well as to clarify a relationship between magmatism and tungsten mineralisation. The conditions of deposit formation were studied using data on the chemical composition of rocks and ores and the oxygen isotopic composition of the ore veins of tungsten deposits.Methods. The elemental composition of rocks was determined by the methods of X-ray fluorescence and standard chemical analysis; the concentration of rare-earth elements was determined by sorption-atomic emission analysis with inductively coupled plasma (Geological Institute SB RAS, Ulan-Ude). The examination of oxygen isotope composition was carried out at the Geological Institute of SB RAS (Ulan-Ude) using a MIR 10-30 system of laser heating with a 100W CO2 laser and 10.6 microns wavelength in the infrared region in the presence of a BrF5 reagent (analyst V.F. Posokhov).Results and conclusions. It was established that granites in the Kukulbey complex of the Antonovogorsky and Bukukinsky tungsten deposits correspond to granites of an ilmenite series, while the ores in the Spokoininsky deposit are associated with the granites of a magnetite series. A close correlation was established between W with Ta, Nb, Hf and As, indicating similar compositions of ore-bearing sources of the tungsten deposits. For Barun-Shiveinsky, Antonovogorsky and Bukukinsky deposits, the oxygen isotope compositions in the fluid in equilibrium with quartz of the productive stage was calculated, indicating the magmatic sources of mineralisation.

Rare-earth elements in the ore of the Bukukinskoye tungsten deposit (the Eastern Transbaikalia)

Research subject. This study investigated the mineral association of quartz-wolframite veins of the Bukukinskoye tungsten deposit, with a particular focus on the content of rare-earth elements and their carrier minerals, their chemical composition and the distribution of light and heavy lanthanides. Materials and methods. The chemical composition of two groups of samples containing different ore minerals, as well as the mineral composition of ores was investigated on 143 samples in thin and polished sections using an AXIO ScopeAI optical polarizing microscope and a LEO 1430 VP scanning electron microscope. Chemical examination of ores was carried out using the ISP MS method. Results. The study of the chemical composition of group samples determined that the content and distribution of REE, the ratio of light and heavy lanthanides in ores depends on the ratio of wolframite and other ore minerals, associated with fluorite and apatite. The main REE concentrator mineral in the wolframite-sulfide-quartz ores of the Bukukinskoye deposit is monazite-(Ce) containing (wt %) Ce (27.09–31.59) La (13.13–17.67), Nd (5.59–10.26), Pr (up to 2.86), Sm (up to 1.14), Th (up to 6.59). Conclusion. The obtained results confirmed our earlier findings for the wolframite of the Sherlova Gora that an increase in the concentration coefficient of heavy lanthanides depends on a decrease in their ionic radius. The contents, mineral forms and ratios of REE of the cerium and yttrium groups in the ore of the Bukukinskоyе deposit can be typochemical signs of greisen tungsten deposits, thus being useful for typification of ore formation in geological forecasting and prospecting.

Quantification of local zinc and tungsten deposits in bone with LA-ICP-MS using novel hydroxyapatite-collagen calibration standards”

Tungsten has recently emerged as a potential toxicant and is known to heterogeneously deposit in bone as reactive polytungstates. Zinc, which accumulates in regions of bone remodeling, also has a...