The genesis of Indo-Sinian granitic plutons with peraluminous and potassium-rich affinities from Hunan Province, China has been investigated by numerical modeling using the numerical code FLAC. On the basis of the reg...The genesis of Indo-Sinian granitic plutons with peraluminous and potassium-rich affinities from Hunan Province, China has been investigated by numerical modeling using the numerical code FLAC. On the basis of the regional geological evolution in South China, we employed a realistic numerical model in an attempt to unravel the influences of basaltic underplating and tectonic crustal thickening on the crustal anatexis. Heat production derived from basaltic underplating (e.g. ca. 220 Ma gabbro xenoliths) can result in dehydration melting of fluid-bearing minerals in crustal rocks such as gneisses and metapelites, but its effect is limited in a relatively short time span (5-15 Ma) and on a small scale. Accordingly, it is very difficult for basaltic underplating to generate the large-scale Indo-Sinian granitic bathliths unless voluminous mafic magmas had been underplated at the lower/middle crust during this period. Alternatively, crustal thickening induced by tectonic compression can also lead to geothermal elevation, during which the temperature at the boundary between lower and middle crusts can be up to or greater than 700°C, triggering dehydration melting of muscovite in gneiss and metapelite. The proportion of melts from muscovite-induced dehydration melting is close to critical melt percentage (?20%) once the thickening factor reaches 1.3. These melts can be effectively transferred to the crust-level magma chamber and form large-scale granitic batholiths. In combination with the Indo-Sinian convergent tectonic setting in South China as well as sparse outcrops of contemporary mafic igneous rocks, we consider that tectonic crustal thickening is likely to be the predominant factor controlling the formation of the Indo-Sinian peraluminous and potassium-rich granitoids in Hunan Province.展开更多
With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern Ch...With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.展开更多
The Quxu （曲水） complex is a typical intrusive among the Gangdese batholiths. Two sets of samples collected from the Mianjiang （棉将） and Niedang （聂当） villages in Quxu County, including gabbro, mafic micro-enc...The Quxu （曲水） complex is a typical intrusive among the Gangdese batholiths. Two sets of samples collected from the Mianjiang （棉将） and Niedang （聂当） villages in Quxu County, including gabbro, mafic micro-enclaves （MME）, and granodiorites in each set, were well dated in a previous SHRIMP zircon U-Pb analysis （47-51 Ma）. In this article, the same zircons of the 6 samples were applied for LA ICP-MS Hf isotopic analysis. The total of 6 samples yields 176Hf/177Hf ratio ranging from 0.282 921 to 0.283 159, corresponding to εHf（t） values of 6.3-14.7. Their Hf depleted-mantle modal ages （TDM） are in the range of 137-555 Ma, and the zircon Hf isotope crustal model ages （TDMC） range from 178 to 718 Ma. The mantle-like high and positive Era（t） values in these samples suggest a mantledominated input of the juvenile source regions from which the batholith originated. The large variations in εHf（t） values, up to 5-ε unit among zircons within a single rock and up to 15-ε unit among zircons from the 6 samples, further suggest the presence of a magma mixing event during the time of magma generation. We suggest that the crustal end-member involved in the magma mixing is likely from the ancient basement within the Lhasa terrane itself. The zircon Hf isotopic compositions further suggest that magma mixing and magma underplating at about 50 Ma may have played an important role in creating the crust of the southern Tibetan plateau.展开更多
The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xie...The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province, and 205.3±1.6 Ma for biotite granite from the Napeng pluton, western Guandong Province, respectively, showing a similar late Indosinian age of crystallization. In combination with other geochronological data from Indosinian granites within the South China Block （SCB）, it is proposed that those late Indosinian granites with an age of -210 Ma and the early Indosinian granites （230-245 Ma） have the similar petrogenesis in identical tectonic setting. The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime. These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.展开更多
AIM: To evaluate carotid intima-media thickening (IMT) and plaques, gallstone disease (GD) and fatty liver (FL) as a function of age. METHODS: In 449 subjects, FL and carotid disease were assessed ultrasonographically...AIM: To evaluate carotid intima-media thickening (IMT) and plaques, gallstone disease (GD) and fatty liver (FL) as a function of age. METHODS: In 449 subjects, FL and carotid disease were assessed ultrasonographically. In a subgroup of 65/449 patients with non-alcoholic fatty liver disease (NAFLD), carotid disease, GD and associated factors were determined. RESULTS: FL of unspecified etiology was more common in younger and GD in older individuals. FL subjects had an increased prevalence of IMT and a decreased prevalence of plaques and manifested carotid disease earlier. Plaques were more common in subjects with GD. Age was an independent predictor of carotid disease outcome and FL was a protective factor for plaques. In NAFLD, there was an inverse correlation between body weight and age and the latter independently predicted carotid findings. CONCLUSION: Cardiovascular risk in patients with FL and NAFLD needs to be assessed as a function of age and body weight.展开更多
基金This work was supported by the Chinese Academy of Sciences (Gram Nos. KZCX2-102 and KZCX3-113)the Ministry of Science and Technology of China (Grant No. G1999043209)the National Natural Science Foundation of China (Grant No. 40002007)
文摘The genesis of Indo-Sinian granitic plutons with peraluminous and potassium-rich affinities from Hunan Province, China has been investigated by numerical modeling using the numerical code FLAC. On the basis of the regional geological evolution in South China, we employed a realistic numerical model in an attempt to unravel the influences of basaltic underplating and tectonic crustal thickening on the crustal anatexis. Heat production derived from basaltic underplating (e.g. ca. 220 Ma gabbro xenoliths) can result in dehydration melting of fluid-bearing minerals in crustal rocks such as gneisses and metapelites, but its effect is limited in a relatively short time span (5-15 Ma) and on a small scale. Accordingly, it is very difficult for basaltic underplating to generate the large-scale Indo-Sinian granitic bathliths unless voluminous mafic magmas had been underplated at the lower/middle crust during this period. Alternatively, crustal thickening induced by tectonic compression can also lead to geothermal elevation, during which the temperature at the boundary between lower and middle crusts can be up to or greater than 700°C, triggering dehydration melting of muscovite in gneiss and metapelite. The proportion of melts from muscovite-induced dehydration melting is close to critical melt percentage (?20%) once the thickening factor reaches 1.3. These melts can be effectively transferred to the crust-level magma chamber and form large-scale granitic batholiths. In combination with the Indo-Sinian convergent tectonic setting in South China as well as sparse outcrops of contemporary mafic igneous rocks, we consider that tectonic crustal thickening is likely to be the predominant factor controlling the formation of the Indo-Sinian peraluminous and potassium-rich granitoids in Hunan Province.
文摘With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic （165±5 Ma）, great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at -165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.
基金supported by the National Basic Research Program of China (Nos. 2009CB421002, 2002CB412600)the Na-tional Natural Science Foundation of China (Nos. 40873023, 40830317, 40672044, 40503005, 40572048, 40473020)+1 种基金111 Project (No. B07011)China Geological Survey (No. 1212010610104)
文摘The Quxu （曲水） complex is a typical intrusive among the Gangdese batholiths. Two sets of samples collected from the Mianjiang （棉将） and Niedang （聂当） villages in Quxu County, including gabbro, mafic micro-enclaves （MME）, and granodiorites in each set, were well dated in a previous SHRIMP zircon U-Pb analysis （47-51 Ma）. In this article, the same zircons of the 6 samples were applied for LA ICP-MS Hf isotopic analysis. The total of 6 samples yields 176Hf/177Hf ratio ranging from 0.282 921 to 0.283 159, corresponding to εHf（t） values of 6.3-14.7. Their Hf depleted-mantle modal ages （TDM） are in the range of 137-555 Ma, and the zircon Hf isotope crustal model ages （TDMC） range from 178 to 718 Ma. The mantle-like high and positive Era（t） values in these samples suggest a mantledominated input of the juvenile source regions from which the batholith originated. The large variations in εHf（t） values, up to 5-ε unit among zircons within a single rock and up to 15-ε unit among zircons from the 6 samples, further suggest the presence of a magma mixing event during the time of magma generation. We suggest that the crustal end-member involved in the magma mixing is likely from the ancient basement within the Lhasa terrane itself. The zircon Hf isotopic compositions further suggest that magma mixing and magma underplating at about 50 Ma may have played an important role in creating the crust of the southern Tibetan plateau.
基金This study was financially supported by the National Natural Science Foundation of China(grants 40421303 and 40234046).
文摘The LA-ICPMS zircon U-Pb geochronology of three typically Indosinian granitic plutons yielded weighted mean ^206pb/^238U ages of 214.1±5.9 Ma and 210.3±4.7 Ma for the biotite monzonitic granites from the Xiema and Xiangzikou plutons in Hunan Province, and 205.3±1.6 Ma for biotite granite from the Napeng pluton, western Guandong Province, respectively, showing a similar late Indosinian age of crystallization. In combination with other geochronological data from Indosinian granites within the South China Block （SCB）, it is proposed that those late Indosinian granites with an age of -210 Ma and the early Indosinian granites （230-245 Ma） have the similar petrogenesis in identical tectonic setting. The Indosinian granites within the SCB might be the products of anatexis of the thickening crust in a compressive regime. These data provide a further understanding for the temporal and spatial distribution of the Indosinian granites and the dynamic evolution of the SCB.
基金Supported by grants from Miur Ministero Istruzione Università e Ricerca Scientifica-PRIN 2004061213_001
文摘AIM: To evaluate carotid intima-media thickening (IMT) and plaques, gallstone disease (GD) and fatty liver (FL) as a function of age. METHODS: In 449 subjects, FL and carotid disease were assessed ultrasonographically. In a subgroup of 65/449 patients with non-alcoholic fatty liver disease (NAFLD), carotid disease, GD and associated factors were determined. RESULTS: FL of unspecified etiology was more common in younger and GD in older individuals. FL subjects had an increased prevalence of IMT and a decreased prevalence of plaques and manifested carotid disease earlier. Plaques were more common in subjects with GD. Age was an independent predictor of carotid disease outcome and FL was a protective factor for plaques. In NAFLD, there was an inverse correlation between body weight and age and the latter independently predicted carotid findings. CONCLUSION: Cardiovascular risk in patients with FL and NAFLD needs to be assessed as a function of age and body weight.
