Widespread in Southern Xizang are intermediate-acidic rocks characterized by their regular distribution in space and time. In order to explore their formation ages and genesis, we have determined the Rb-Sr whole rock ...Widespread in Southern Xizang are intermediate-acidic rocks characterized by their regular distribution in space and time. In order to explore their formation ages and genesis, we have determined the Rb-Sr whole rock isochron ages on granodiorite from the Quxu pluton in Kangdese belt (18m.y., Sr^87/Sr^88 initial ratio = 0.7036), gneissose two-mica granite from the Kangmar pluton in Lhagoi Kangri belt (484.55 ± 6.34 m.y.,Sr^87/Sr^86 initial ratio = 0.7186 ± 0.0018) ; and tourmaline-muscovite granite from the Gabug pluton in Himalaya belt (42.95 ± 2.6 m.y., Sr^87/Sr^84 initial ratio=0.7478±0.00097). From the initial Sr^87/Sr^86 ratios it is shown that the granodiorites are most likely to be derived from the upper mantle; the gneissose two-mica granites may contain significant amounts of sialic material during emplacement; and the tourmalinemusco vite granites are typically of crustal origin.展开更多
The Gangdise rockk belt is the northmost an4 petrochemically the most complex one of the three east-west striking intermedlate-acid rock belt in south Xizang. Rh-Sr whole rock isochronous dating was conducted on sampl...The Gangdise rockk belt is the northmost an4 petrochemically the most complex one of the three east-west striking intermedlate-acid rock belt in south Xizang. Rh-Sr whole rock isochronous dating was conducted on samples of different rocks collected aerossing this belt from Quxur throwgh Lhasa to Yangbajan, Results show that these rocks are not contemporaneous and can be roughly assigned to four periods: Indosinian (240±30 my), Early Yenshanian (160--180my), Late Yenshanian (80--100 my), and Himalayanian (20-40 my). Their initial ratios of Sr isotopes are relatively low (0.7033--0.7054). The relationship between Rb, Sr and the major components such as SiO2, K2Oand FeO are also investigated. It seems that, the formation and development of the Gangdise belt can be obviously related with the subduction and collision of the Indian plate with the Eurasian plate. The material that formed this rock belt probably originated from the upper marital or the partial molten products from oceanic crust.展开更多
Xifeng hot spring in Guizhou province is a famous health resort. The spring water is 53-56℃ with a stable flow of more than 1000 tons per day. All the springs emerge on both sides along a normal fault in Sinian Dengy...Xifeng hot spring in Guizhou province is a famous health resort. The spring water is 53-56℃ with a stable flow of more than 1000 tons per day. All the springs emerge on both sides along a normal fault in Sinian Dengying limestone. Water analysis shows that the spring waters contain a number of components beneficial to human health. The concentrations of Hg and F are relatively high but render no immediate harm to human body. Radon contents in fresh spring water and stcam are 11.14 and 32.73 Mach respectively as determined by a type FD-105 electrometer calibrated with Radium standard source, Radium content in spring water is only 3.66×10^-13 g/liter, indicating that radium occurs in free state rather than as a product of radium decay. On the basis of tritium content and environmental geochemical investigation, the spring has not been affected by nuclear tests and its age is at least 30 yrs. The spring is formed by peranlsting surface water down to great depth along fault cracks, heated as a result of normal geothermal gradient, and seeking their way out along the cracks in Sinian dolomite under the pressure of overlying strata.展开更多
The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The h...The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The highest peak of the Mt. Namjag.展开更多
文摘Widespread in Southern Xizang are intermediate-acidic rocks characterized by their regular distribution in space and time. In order to explore their formation ages and genesis, we have determined the Rb-Sr whole rock isochron ages on granodiorite from the Quxu pluton in Kangdese belt (18m.y., Sr^87/Sr^88 initial ratio = 0.7036), gneissose two-mica granite from the Kangmar pluton in Lhagoi Kangri belt (484.55 ± 6.34 m.y.,Sr^87/Sr^86 initial ratio = 0.7186 ± 0.0018) ; and tourmaline-muscovite granite from the Gabug pluton in Himalaya belt (42.95 ± 2.6 m.y., Sr^87/Sr^84 initial ratio=0.7478±0.00097). From the initial Sr^87/Sr^86 ratios it is shown that the granodiorites are most likely to be derived from the upper mantle; the gneissose two-mica granites may contain significant amounts of sialic material during emplacement; and the tourmalinemusco vite granites are typically of crustal origin.
文摘The Gangdise rockk belt is the northmost an4 petrochemically the most complex one of the three east-west striking intermedlate-acid rock belt in south Xizang. Rh-Sr whole rock isochronous dating was conducted on samples of different rocks collected aerossing this belt from Quxur throwgh Lhasa to Yangbajan, Results show that these rocks are not contemporaneous and can be roughly assigned to four periods: Indosinian (240±30 my), Early Yenshanian (160--180my), Late Yenshanian (80--100 my), and Himalayanian (20-40 my). Their initial ratios of Sr isotopes are relatively low (0.7033--0.7054). The relationship between Rb, Sr and the major components such as SiO2, K2Oand FeO are also investigated. It seems that, the formation and development of the Gangdise belt can be obviously related with the subduction and collision of the Indian plate with the Eurasian plate. The material that formed this rock belt probably originated from the upper marital or the partial molten products from oceanic crust.
文摘Xifeng hot spring in Guizhou province is a famous health resort. The spring water is 53-56℃ with a stable flow of more than 1000 tons per day. All the springs emerge on both sides along a normal fault in Sinian Dengying limestone. Water analysis shows that the spring waters contain a number of components beneficial to human health. The concentrations of Hg and F are relatively high but render no immediate harm to human body. Radon contents in fresh spring water and stcam are 11.14 and 32.73 Mach respectively as determined by a type FD-105 electrometer calibrated with Radium standard source, Radium content in spring water is only 3.66×10^-13 g/liter, indicating that radium occurs in free state rather than as a product of radium decay. On the basis of tritium content and environmental geochemical investigation, the spring has not been affected by nuclear tests and its age is at least 30 yrs. The spring is formed by peranlsting surface water down to great depth along fault cracks, heated as a result of normal geothermal gradient, and seeking their way out along the cracks in Sinian dolomite under the pressure of overlying strata.
文摘The Mt. Namjagbarwa region (thereafter referred to as MNR) is located in the southeast of Xizang Autonomous Region, China (29°37′51″ N, 95°03′31″E), and belongs to the eastern part of the Himalaya. The highest peak of the Mt. Namjag.
