Xiba granitic pluton is located in South Qinling tectonic domain of the Qinling orogenic belt and consists mainly of granodiorite and monzogranite with significant number of microgranular quartz dioritic enclaves. SHR...Xiba granitic pluton is located in South Qinling tectonic domain of the Qinling orogenic belt and consists mainly of granodiorite and monzogranite with significant number of microgranular quartz dioritic enclaves. SHRIMP zircon U-Pb isotopic dating reveals that the quartz dioritic enclaves formed at 214±3 Ma, which is similar to the age of their host monzogranite （218±1 Ma）. The granitoids belong to high-K calc-alkaline series, and are characterized by enriched LILEs relative to HFSEs with negative Nb, Ta and Ti anomalies, and right-declined REE patterns with （La/Yb） N ratios ranging from 15.83 to 26.47 and δEu values from 0.78 to 1.22 （mean= 0.97）. Most of these samples from Xiba granitic pluton exhibit εNd（t） values of 8.79 to 5.38, depleted mantle Nd model ages （T DM ） between 1.1 Ga and 1.7 Ga, and initial Sr isotopic ratios （ 87 Sr/ 86 Sr） i from 0.7061 to 0.7082, indicating a possible Meso-to Paleoproterozoic lower crust source region, with exception of samples XB01-2-1 and XB10-1 displaying higher （ 87 Sr/ 86 Sr） i values of 0.779 and 0.735, respectively, which suggests a contamination of the upper crustal materials. Quartz dioritic enclaves are interpreted as the result of rapid crystallization fractionation during the parent magmatic emplacement, as evidenced by similar age, texture, geochemical, and Sr-Nd isotopic features with their host rocks. Characteristics of the petrological and geochemical data reveal that the parent magma of Xiba granitoids was produced by a magma mingling process. The upwelling asthenosphere caused a high heat flow and the mafic magma was underplated into the bottom of the lower continent crust, which caused the partial melting of the lower continent crustal materials. This geodynamic process generated the mixing parent magma between mafic magma from depleted mantle and felsic magma derived from the lower continent crust. Integrated petrogenesis and tectonic discrimination with regional tectonic evolution of the Qinling orogen, it is suggested that the granitoids are most likely products in a post-collision tectonic setting.展开更多
Through field investigation, field surveying and mapping, image analysis, and other methods, this paper discusses the spatial distribution and morphological characteristics of Tibetan settlements around Xiba Temple in...Through field investigation, field surveying and mapping, image analysis, and other methods, this paper discusses the spatial distribution and morphological characteristics of Tibetan settlements around Xiba Temple in two and three dimensions. It finds that under the influence of the spatial order culture of Buddhist “mandala,” Tibetan settlements in the surrounding area of Xiba Temple are characterized by centripetal, symmetrical, and vertical distribution. They are typical representatives of Tibetan settlements built around the temple in the mountain area. The results of this paper may provide a new idea for studying the spatial pattern and spatial structure of Tibetan temple settlements and their surrounding settlements.They can also be used to guide the spatial distribution pattern of Tibetan-inhabited villages under the background of religious culture, and guide the protection, planning, and construction of cultural landscapes in traditional Tibetan settlements.展开更多
基金supported by the National projects of Scientific and Technological Support (Grant Nos.2011BAB04B05 and 2006BAB01A11)National Natural Science Foundation of China (Grant Nos.41072143 and 41072169)
文摘Xiba granitic pluton is located in South Qinling tectonic domain of the Qinling orogenic belt and consists mainly of granodiorite and monzogranite with significant number of microgranular quartz dioritic enclaves. SHRIMP zircon U-Pb isotopic dating reveals that the quartz dioritic enclaves formed at 214±3 Ma, which is similar to the age of their host monzogranite （218±1 Ma）. The granitoids belong to high-K calc-alkaline series, and are characterized by enriched LILEs relative to HFSEs with negative Nb, Ta and Ti anomalies, and right-declined REE patterns with （La/Yb） N ratios ranging from 15.83 to 26.47 and δEu values from 0.78 to 1.22 （mean= 0.97）. Most of these samples from Xiba granitic pluton exhibit εNd（t） values of 8.79 to 5.38, depleted mantle Nd model ages （T DM ） between 1.1 Ga and 1.7 Ga, and initial Sr isotopic ratios （ 87 Sr/ 86 Sr） i from 0.7061 to 0.7082, indicating a possible Meso-to Paleoproterozoic lower crust source region, with exception of samples XB01-2-1 and XB10-1 displaying higher （ 87 Sr/ 86 Sr） i values of 0.779 and 0.735, respectively, which suggests a contamination of the upper crustal materials. Quartz dioritic enclaves are interpreted as the result of rapid crystallization fractionation during the parent magmatic emplacement, as evidenced by similar age, texture, geochemical, and Sr-Nd isotopic features with their host rocks. Characteristics of the petrological and geochemical data reveal that the parent magma of Xiba granitoids was produced by a magma mingling process. The upwelling asthenosphere caused a high heat flow and the mafic magma was underplated into the bottom of the lower continent crust, which caused the partial melting of the lower continent crustal materials. This geodynamic process generated the mixing parent magma between mafic magma from depleted mantle and felsic magma derived from the lower continent crust. Integrated petrogenesis and tectonic discrimination with regional tectonic evolution of the Qinling orogen, it is suggested that the granitoids are most likely products in a post-collision tectonic setting.
基金supported by the Youth Program of the National Natural Science Foundation of China(NSFC)entitled by Research on the Characteristics and Evolution Mechanism of Settlement Landscape Based on Multidimensional Index in the Upper Minjiang River(No.52008342)the NSFC Regional Program entitled by Spatial Mechanism and Method for Optimizing Village Settlements in the Longitudinal Ridge and Valley Area from a Territorial Space Perspective(No.52168012)。
文摘Through field investigation, field surveying and mapping, image analysis, and other methods, this paper discusses the spatial distribution and morphological characteristics of Tibetan settlements around Xiba Temple in two and three dimensions. It finds that under the influence of the spatial order culture of Buddhist “mandala,” Tibetan settlements in the surrounding area of Xiba Temple are characterized by centripetal, symmetrical, and vertical distribution. They are typical representatives of Tibetan settlements built around the temple in the mountain area. The results of this paper may provide a new idea for studying the spatial pattern and spatial structure of Tibetan temple settlements and their surrounding settlements.They can also be used to guide the spatial distribution pattern of Tibetan-inhabited villages under the background of religious culture, and guide the protection, planning, and construction of cultural landscapes in traditional Tibetan settlements.
