An Isotope Study of the Dzhida Mo–W Ore Field (Western Transbaikalia, Russia)

• Main Authors: German S. Ripp, Olga K. Smirnova, Ivan A. Izbrodin, Eugeny I. Lastochkin, Mikhail O. Rampilov, Viktor F. Posokhov
• Format: Article
• Language: English
• Published: MDPI AG 2018-11-01
• Series: Minerals
• Subjects: Mo–W deposits; oxygen isotopes; fluid source; Western Transbaikalia
• Online Access: https://www.mdpi.com/2075-163X/8/12/546
• ISSN: 2075-163X

The Dzhida ore field includes Pervomaika (Mo), Inkur (W) and Kholtoson (W) deposits. This article presents stable and radiogenic isotopic data (O, C, D, S, Sr and Nd) in an attempt to better understand the petrogenetic processes and the problem concerning the sources of ore-forming fluids. Granites from the Pervomaika deposit, which includes Mo-ores, as well as the syenite dikes that precede W-mineralization, have low δ¹⁸O values (about 5‰ and 4‰ respectively), and low initial ratios ⁸⁷Sr/⁸⁶Sr (0.704⁻0.705). The εNd (T) values (+0.9⁻−1.1) in granites and syenites are close to the evolution trend of the mantle-derived source. It was determined that a mantle-derived source was involved in ore-forming processes. It was also confirmed that δ³⁴S values in sulfide minerals (molybdenite, pyrite, sphalerite, galena, and chalcopyrite) were close to the meteoric standard (from −2‰ to +2‰). The δ¹³C and δ¹⁸O values in carbonate minerals (rhodochrosite and ankerite) of the Kholtoson deposit are located within the primary igneous carbonatite (PIC)-square, as a possible juvenile source of CO₂. This was also confirmed by the δ¹⁸O and δD values in muscovite from greisens (4.2‰⁻6.5‰ δ¹⁸O, ⁻78.8‰ … ⁻84.0‰ δD). The δ¹⁸O values calculated in a fluid equilibrated with hydrothermal minerals indicated a meteoric origin.