Isotope tracers for deep-seated fluids and noble gases

• Published in: Acta geochimica Vol. 32; no. 2; p. 195
• Main Authors: Wang, Baode, Niu, Shuyin, Sun, Aiqun, Zhang, Jianzhen, Wang, Xiang, Wang, Chuen
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01-06-2013
• Subjects: Earth; Geochemistry; Granite; Isotopes; Lithosphere; Silver; Volcanic springs
• ISSN: 2096-0956; 2365-7499
• DOI: 10.1007/s11631-013-0622-6

The role of He and Ar isotopes in tracing the source of ore fluids has aroused great attention of the broad masses of the geological researchers. On the basis of lots of test and measurement of He and Ar isotopes in sulfides from Au, Ag polymetallic ore deposits in northern China, statistics has been made on the published He and Ar isotope data from 27 gold deposits, 13 silver polymetallic ore deposits, 8 polymetallic ore deposits, 1 rare-earth deposit, 3 oceanic incrustations, 3 volcanic springs and their wall rocks and granites. The statistical results indicate that the ^sup 3^He/^sup 4^Ar (Ã--10^sup â '6^) values of the Au, Ag polymetallic ore deposits are within the range of 0.24â[euro]"9.39, with an average of 3.34Ã--10^sup â '6^; the He/Ar values, 0.007â[euro]"6.01,with an average of 2.37; the ^sup 40^Ar/^sup 36^Ar values, 265.75â[euro]"2361, with an average of 699.0; the ^sup 4^He/^sup 40^Ar values, 0.0020â[euro]"643.86, with an average of 5.85, the ^sup 3^He/^sup 4^Ar (Ã--10^sup â '6^) values of gneiss and granite surrounding the mining area, 0.001â[euro]"1.79, with an average of 1.00Ã--10^sup â '6^, reflecting great differences in source. Mantle-source He in 48 Au, Ag polymetallic ore deposits accounts for 4.55%â[euro]"83.06%, averaging 29.91%. It falls near the mantle-source region which can be seen in the He isotopic concentration diagram and the ^sup 3^He/^sup 4^He(R/Ra)-^sup 40^Ar/^sup 36^Ar plot. Studies suggested that the ore-forming materials for endogenic Au, Ag polymetallic ore deposits should be derived from the deep interior of the Earth, and with the multi-stage evolution of mantle plumes the deep-seated ore fluids would be transported from the deep interior of the Earth to the shallow levels. During this process the mixing of crust/mantle-source fluids would inevitably occur, therefore, the value range always lies between the mantle and the crust.[PUBLICATION ABSTRACT]