Mantle-derived magmatic gas releasing features at the Rehai area, Tengchong county, Yunnan Province, China

摘要

This paper deals with the chemical and isotopic compositions of escaped gases from the Rehai geothermal area in Tengchong county of Yunnan Province. Results indicate that there is the mantle-derived magmatic intrusion in shallow crust at this area. Modern mantle-derived mag- matic volatiles are being released currently in a steady stream by way of active faults. The es- caped gases are mostly composed of CO_2, together with subordinate amounts of H_2S, N_2, CH_4, SO_2, CO and He. At the studied area, the north-south directed fault is the deepest, and it may be Interlinked with the deep-seated thermal reservoir that would be directly recharged by the man- Tle-derived magmatic volatile. The He. C isotopic evidence reveals that the modern active magma Beneath Rehai area may originate from the historical mantle-derived magma which caused the Latest eruptive activity of volcanoses in that region.