Origin of the Dashuigou independent tellurium deposit at Qinghai–Xizang Plateau: constraints from the light stable isotopes C, O, and H

Abstract

By studying the light isotopic compositions of carbon, oxygen, and hydrogen, combined with previous research results on the ore-forming source of the deposit, the authors try to uncover its metallogenic origin. The δ¹⁸O and δ¹³C isotope signatures of dolomite samples vary between 10.2 and 13.0‰, and between −7.2 and −5.2‰, respectively, implying that the carbon derives from the upper mantle. δD and δ¹⁸O of quartz, biotite, and muscovite from different ore veins of the deposit vary between −82 and −59‰, and between 11.6 and 12.4‰, respectively, implying that the metallogenic solutions are mainly magmatic. According to the relevant research results of many isotope geologists, the fractionation degree of hydrogen isotopes increases as the depth to the Earth’s core increases, and the more differentiated the hydrogen isotopes are, the lower their values will be. In other words, mantle-derived solutions can have extremely low hydrogen isotope values. This means that the δD‰ value − 134 of the pyrrhotite sample numbered SD-34 in this article may indicate mantle-derived ore-forming fluid of the deposit. The formation of the Dashuigou tellurium deposit occurred between 91.71 and 80.19 Ma.