【摘 要】
：
The East Kunlun Orogenic Belt(EKOB),which is in the northern part of the Greater Tibetan Plateau,contains voluminous Late Triassic intermediate-felsic volcanic rocks.In the east end of the EKOB,we identified highly differentiated peralkaline-like Xiangrid
【机 构】
：
Institute of Geology and Paleontology,Linyi University,Linyi 276000,China;Laboratory for Marine Geol
论文部分内容阅读
The East Kunlun Orogenic Belt(EKOB),which is in the northern part of the Greater Tibetan Plateau,contains voluminous Late Triassic intermediate-felsic volcanic rocks.In the east end of the EKOB,we identified highly differentiated peralkaline-like Xiangride rhyolites(～209 Ma)that differ from the wide-spread andesitic-rhyolitic Elashan volcanics(～232-225 Ma)in terms of their field occurrences and min-eral assemblages.The older,more common calc-alkaline felsic Elashan volcanics may have originated from partial melting of the underthrust Paleo-Tethys oceanic crust under amphibolite facies conditions associated with continental collision.The felsic Elashan volcanics and syn-collisional granitoids of the EKOB are different products of the same magmatic event related to continental collision.The Xiangride rhyolites are characterized by elevated abundances of high field strength elements,especially the very high Nb and Ta contents,the very low Ba,Sr,Eu,P,and Ti contents;and the variably high 87Sr/86Sr ratios(up to 0.96),exhibiting remarkable similarities to the characteristic peralkaline rhyolites.The primitive magmas parental to the Xiangride rhyolites were most likely alkali basaltic magmas that underwent pro-tracted fractional crystallization with continental crust contamination.The rock associations from the early granitoids and calc-alkaline volcanic rocks to the late alkaline basaltic dikes and peralkaline-like rhyolites in the Triassic provide important information about the tectonic evolution of the EKOB from syn-collisional to post-collisional.We infer that the transition from collisional compression to post-collisional extension occurred at about 220 Ma.
其他文献
On 10 th Oct. and 3 rd Nov. 2018, two successive landslides occurred in the Jinsha River catchment at Baige Village, Tibet Autonomous Region, China. The landslides blocked the major river and formed t
One important step in binary modeling of environmental problems is the generation of absence-datasets that are traditionally generated by random sampling and can undermine the quality of outputs. To s
目的探讨肺动脉高压患者次极量运动参数与峰值摄氧量(P–VO2)的相关性。方法回顾性分析2010年10月至2013年10月在同济大学附属上海市肺科医院住院治疗的106例肺动脉高压患者(肺动脉高压组)的临床资料，包括肺功能、氨基末端脑利钠肽前体(NT–proBNP)测定、6 min步行试验、右心导管检查及心肺运动试验的结果资料，并以同期无吸烟史、无心肺疾病及基线资料匹配的20名健康志愿者为对照组进行对
Stream morphology is an important indicator for revealing the geomorphological features and evolution of the Yangtze River.Existing studies on the morphology of the Yang-tze River focus on planar features.However,the vertical features are also important.V
Efflorescent nanophases(NPs)are found as a transitory accumulation of potentially hazardous elements(PHEs),particularly in tropical climates.The central objective of this study was to investigate the distribution of PHEs with NPs through the evaporative f
Air pollution is a grand challenge of our time due to its multitude of adverse impacts on environment and society,with the scale of impacts more severe in developing countries,including China.Thus,China has initiated and implemented strict air pollution c
Defining impact significance is the main technical task that influences decision-making during the Environmental Licensing Procedure(ELP).The ELP begins with screening to determine potentially signif-icant impacts of the proposed project.Scoping then foll