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...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 escaped gases are mostly composed of CO2, together with subordinate amounts of H2S, N2, H2, CH4, SO2, 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 mantle-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 volcanoes in that region.展开更多
Fluids and noble gases of mantle-derived materials are important tracers for the mantle information. Compositions of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, Ch...Fluids and noble gases of mantle-derived materials are important tracers for the mantle information. Compositions of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China, were tested by the methods of heat-bursting and heat-melting respectively. The fluids are mainly composed of CO2, CO and H2, which account for about 90% of the total, and are similar to the mantle-derived rocks from other areas of eastern China; ratios of 3He/4He in almost all samples range from 0.82 Ra to 2.74 Ra, whereas 40Ar/36Ar from 299.5 to 758.8. Both ranges are much lower than those of the typical ocean mantle-derived samples (such as MORB) and primarily reflect the influences of the atmospheric components and the radiogenic isotopes. Ratios of C/3He range from 27.6×109 to 1050×109, N2/Ar from 927 to 56612, and N2/3He from 2.5×109 to 27×109, similar to those in western United States and New Zealand which belong to the tectonic plate collision regions. The ratios fall in the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting the influences of the atmosphere and the crusts with organic components. Our results suggest that the composition of the primary fluids and the isotopic ratios of the noble gases may either reflect the evolution process of mantle-derived rocks connected with the rise and eruption of magma, or the influence of the ancient subduction-plate on the continental mantle of this region.展开更多
On the basis of the chemical components and stable isotopic compositions of escaped gases from the Tianchi volcanic geothermal area, the material sources of these gases are discussed, presenting that they are mainly d...On the basis of the chemical components and stable isotopic compositions of escaped gases from the Tianchi volcanic geothermal area, the material sources of these gases are discussed, presenting that they are mainly derived from the residual mantle-derived magma in the crust; Changbai geothermal area may be directly interlinked with the eruption canal in history; there is a stable reservoir of the geothermal water and the deep-seated gases under the Changbai geothermal area, with water temperature of the reservoir being about (166±9)℃.展开更多
文摘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 escaped gases are mostly composed of CO2, together with subordinate amounts of H2S, N2, H2, CH4, SO2, 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 mantle-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 volcanoes in that region.
基金supported by the National Natural Science Foundation of China(Grant No.49972081)the Natural Science Foundation of Gansu Province of China(Grant No.3ZS041-A25-010).
文摘Fluids and noble gases of mantle-derived materials are important tracers for the mantle information. Compositions of primary fluids and noble gases in mantle-derived minerals from the Yishu area, Shandong Province, China, were tested by the methods of heat-bursting and heat-melting respectively. The fluids are mainly composed of CO2, CO and H2, which account for about 90% of the total, and are similar to the mantle-derived rocks from other areas of eastern China; ratios of 3He/4He in almost all samples range from 0.82 Ra to 2.74 Ra, whereas 40Ar/36Ar from 299.5 to 758.8. Both ranges are much lower than those of the typical ocean mantle-derived samples (such as MORB) and primarily reflect the influences of the atmospheric components and the radiogenic isotopes. Ratios of C/3He range from 27.6×109 to 1050×109, N2/Ar from 927 to 56612, and N2/3He from 2.5×109 to 27×109, similar to those in western United States and New Zealand which belong to the tectonic plate collision regions. The ratios fall in the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting the influences of the atmosphere and the crusts with organic components. Our results suggest that the composition of the primary fluids and the isotopic ratios of the noble gases may either reflect the evolution process of mantle-derived rocks connected with the rise and eruption of magma, or the influence of the ancient subduction-plate on the continental mantle of this region.
基金Project supported by the National Natural Science Foundation of China
文摘On the basis of the chemical components and stable isotopic compositions of escaped gases from the Tianchi volcanic geothermal area, the material sources of these gases are discussed, presenting that they are mainly derived from the residual mantle-derived magma in the crust; Changbai geothermal area may be directly interlinked with the eruption canal in history; there is a stable reservoir of the geothermal water and the deep-seated gases under the Changbai geothermal area, with water temperature of the reservoir being about (166±9)℃.
