关键词: NW向断裂, Rn,Th射气探查, 腾冲热海地热区

Abstract: The Rehai area of Tengchong County, Yunnan Province is a well-known volcanic geothermal field in China. During the last few years, the hydrothermal activity was very strong in this area. Almost all of the boiling springs, spouting boiling springs and more than 20 times of hydrothermal explosion events since 1993 in this area are distributed along the NW-trending fault, indicating that the fault has been recently very active. The results of Th and Rn radioactive gas measurements verify that a NW-trending fault with a strike of 290? does exist in this area, and that the fault is presently still very active. The geological evidence and related research results indicate that the locations of magma chamber in the crust, the ring tectonic zone, the upwarped district of the Maanshan volcano and the Rehai geothermal field are all distributed just along northwest direction, which is roughly the same as the NW-trending fault. This may imply that the formation of this fault might be related to magmatic activity in the crust of the Tengchong volcanic region. As such, the recent strong activity of geothermal fluid in the studied area must be the surficial manifestation of the enhanced activity of deep-seated magma, to which enough attention should be paid.

Key words: NW-trending fault, Rn and Th radioactive gas measurement, Rehai volcanic geothermal field, Tengchong