Composition, formation conditions, and genesis of the Talatui gold deposit, the Eastern Transbaikal Region, Russia

Abstract

The mineral composition of the Talatui gold deposit has been studied with modern methods. Previously unknown minerals (ilmenite, siegenite, glaucodot, wittichenite, matildite, hessite, pilsenite, zircon, tremolite, cummingtonite, hercynite, and goethite) have been identified in the ore. A high Re content has been detected in molybdenite. The spatiotemporal separation of Au and Ag is caused by different mineral species of these elements and their diachronous precipitation during the ore-forming process. Gold crystallized along with early mineral assemblages, beginning from virtually pure gold (the fineness is 996). Silver precipitated largely at the end of the process as hessite ( Ag 2 Te ) and matildite ( AgBiS 2 ). The temperature of ore deposition varied from 610 to 145 ° C, the pressure was 3370-110 bar, and the salt concentration ranged from 56.3 to 0.4 wt % NaCl equiv. The heterogeneous state (boiling) of fluid at the early stages has been documented. The chemical and isotopic compositions of the fluid testify to its magmatic nature and the participation of meteoric water at late stages in the ore-forming process. Thermodynamic modeling reproduces the main specific features of ore formation, including separation of Au and Ag. A physicochemical model of the gold mineralization in the Darasun ore district has been proposed. On the basis of several attributes, the Talatui deposit has been referred to the porphyry gold-copper economic type.

Tourmalinization at the Darasun goldfield, Eastern Transbaikalia: Compositional, fluid inclusion and isotopic constraints

“…Deposits in the Darasun gold-bearing area are one of the main types of gold mineralization in Eastern Transbaikalia, and locally referred to as the "Darasun type" (Timofeyevsky, 1972). The deposits are also referred to the gold-porphyry or gold-copper-porphyry-type (Prokof'yev et al, 2000;Sillitoe, 2000), and there are many studies of the gold deposits (Timofeyevsky, 1972;Prokof'yev et al, 2000;Sakharova, 1972;Lyakhov, 1975;Zorina, 1993;Prokof'ev and Zorina, 1994;Yurgenson and Yurgenson, 1995;Prokof'ev et al, 2004Prokof'ev et al, , 2005a. After a long duration of no or minimal mining, the gold deposits of the Darasun area deposits are again mined and reinvestigated.…”

Geochemical evolution of tourmaline in the Darasun gold district, Transbaikal region, Russia: evidence from chemical and boron isotopic compositions

“…Tourmaline at Talatui (sample 154) was sampled from a quartz-pyrite vein hosted in altered metagabbro. According to Prokof'ev et al (2007), high-fineness gold (951-996) precipitated nearly simultaneous with tourmaline (Fig 2b), whereas gold with lower fineness (777-875) was deposited simultaneously with late pyrite and chalcopyrite (Fig. 2c).…”

“…Previous studies of the Darasun district have concentrated on the geological setting, descriptive mineralogy, and fluid inclusions of the deposits (e.g. Sakharova 1972;Timofeyevsky 1972;Lyakhov 1975;Zorina 1993;Prokof'ev and Zorina 1994;Zorin et al 2001;Prokofiev et al 2010Prokofiev et al , 2012Prokof'ev et al 2004Prokof'ev et al , 2007Spiridonov et al 2010). Recently, Baksheev et al (2011) studied tourmaline from quartz-carbonate veins from the Darasun deposit, with emphasis on the high proportion of ferric vs. ferrous iron determined by Mössbauer spectroscopy.…”

Coexisting Tetrahedrite–(Zn) and Sphalerite at the Teremki Gold-Ore Deposit (East Transbaikalia): Chemical Composition and Formation Conditions

“…The Teremki deposit is located 5 km from the large Darasun gold deposit. Mineral assemblages at these deposits are similar, although assemblages at the Teremki deposit have not been studied in the same detail as those of the Darasun deposit (Timofeevskii, 1972;Prokof'ev et al, 2004;Lyubimtseva et al, 2018aLyubimtseva et al, , 2018betc.). The formation conditions of the productive stage at the Teremki deposit have been determined from the study of fluid inclusions in quartz (Prokof'ev et al, 2004;Prokofiev et al, 2010), whereas ore minerals of variable composition (e.g., tetrahedrite and sphalerite, which may be associated with native gold) have not been studied in this regard.…”