Characteristics of gas geochemistry in Yangbajing geothermal field, Tibet

作     者：Ping Zhao Ji Dor Tingli Liang Jian Jin Haizheng Zhang 

作者机构：Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China Tibet Bur Geol & Mineral Resources Geothermal Geol Team Lhasa 851400 Peoples R China 

出 版 物：《Chinese Science Bulletin》 (科学通报(英文版))

年 卷 期：1998年第43卷第21期

页      面：1770-1777页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

基　　金：ThisworkwassupportedbytheNationalNaturalScienceFoundationofChina (GrantNos.4940 2 0 39and 496 72 16 8)andInternationalAtomicEnergyAgency (GrantNo .90 95 ) 

主　　题：gas geochemistry isotope reservoir Yangbajing Tibet. 

摘      要：CO 2 is a main component of gases in the Yangbajing geothermal field, usually higher than 85 in volume; others are N 2, H 2S, H 2, CH 4, etc. Helium R/R a ratios, ranging from 0.14 to 0.46, indicate a crustal component to be dominant in the gases. δ 13C-CO 2 values and δ 34S-H 2S values are in the range -7.72‰--11.33‰ and 0.2‰-8.3‰, respectively. The gases are inferred to mostly derive from the partial melting of the Nyainqentanglha core complex. The gases of shallow and deep reservoirs are distinctive in chemical compositions and δ 34S-H 2S values, which shows their different flowing paths and physical-chemical processes. Sulphur does not approach isotopic equilibrium between H 2S and SO 2- 4 species in both reservoirs. Significance of steam chemical monitoring is also discussed.