Investigation of the petrogenesis and the origin of zircons from the volcanic rocks of the Liujiaping Group of the back-Longmenshan tectonic belt in the northwest margin of the Yangtze Block is conducted by analysis o...Investigation of the petrogenesis and the origin of zircons from the volcanic rocks of the Liujiaping Group of the back-Longmenshan tectonic belt in the northwest margin of the Yangtze Block is conducted by analysis of U-Pb geochronology and geochemistry. Results show that selected zircons are characterized by internal oscillatory zonings and high Th/U ratios （0.43-1.18）, indicating an igneous origin. Geochronological results of LA-ICP-MS U-Pb dating of the Liujiaping Group zircons yield an age of 809 - 11 Ma （MSWD = 2.2）, implying that the volcanic rocks were formed in the Late Neoproterozoic. Geochemical analysis shows that the rocks are calc-alkaline, supersaturated in AI, and metaluminous to weakly peraluminous. Rare-earth elements are present at high concentrations （96.04-265.48 ppm） and show a rightward incline and a moderately negative Eu anomaly, similar to that of continental rift rhyolite. Trace element geochemistry is characterized by evident negative anomalies of Nb, Ta, P, Th, Ti, inter alia, and strong negative anomalies of K, Rb, Sr, et al. We conclude that the Liujiaping Group volcanic rocks resulted from typical continental crust source petrogenesis and were formed in a continental margin setting, which had no relation to subduction, and thus, were the products of partial melting of the lower crust due to crustal thickening caused by active continental margin subduetion and arc-continent collision orogeny in the northwestern Yangtze Block and were triggered by the breakup of the Rodinia supercontinent during the Neoproterozoic.展开更多
Objective High-pressure(HP)and ultrahigh-pressure(UHP)minerals tend to be preserved in mafic and ultramafic metamorphic rocks(e.g.eclogites and garnet amphibolite)rather than felsic rocks.Generally,HP and UHP rocks ar...Objective High-pressure(HP)and ultrahigh-pressure(UHP)minerals tend to be preserved in mafic and ultramafic metamorphic rocks(e.g.eclogites and garnet amphibolite)rather than felsic rocks.Generally,HP and UHP rocks are thought to be formed as a result of the tectonic burial or subduction of oceanic crust or thicked continental lithosphere to depths corresponding to the eclogite facies metamorphism,followed by fast uplift(Ernst et al.,2007).展开更多
The East Kunlun Orogenic Belt(EKOB)in northeast margin of the Qinghai-Tibetan Plateau is an important part of the Central Orogenic System(COS).During the long-time geological evolution,complicated tectono
1 Introduction East Kunlun orogen(EKO)stretching more than 1000km in E-W extension is located in the western segment of Central Orogen Belt(COB),China(Xu et al.,2006,Li et al.,2014).There outcropped Cambrian ophiolites
A new near α-titanium alloy Ti12.5Zr2.5Nb2.5Ta （TZNT） for surgical implants was designed. The potentiodynamic technique was performed to investigate the corrosion behaviors of TZNT in Ringer＇s solution, and Ti6A14...A new near α-titanium alloy Ti12.5Zr2.5Nb2.5Ta （TZNT） for surgical implants was designed. The potentiodynamic technique was performed to investigate the corrosion behaviors of TZNT in Ringer＇s solution, and Ti6A14V, Ti6Al7Nb, and TA2 were taken as comparison. The structure of the passive film was analyzed using an X-ray photoelectron spectrometer （XPS）. The results indicate that TZNT possesses better corrosion resistance, when compared with Ti6A14V, Ti6A17Nb, and TA2. The passive film formed on the TZNT surface is composed of oxides, such as TiO2, ZrO2, Nb2O5, and Ta2O5. The elements Zr and Ta are rich, whereas Ti and Nb are poor in the passive film. The addition of Zr, Nb, and Ta with relatively low electrochemical reaction potentials can reduce the anode activity and improve passive properties. Other than that, oxides such as ZrO2, Nb2O5, and Ta2O5 with the nobler equilibrium constants make the passive film more stable.展开更多
Objective Neocalamites is a common plant fossil from the Triassic to the Middle Jurassic. Neocalamites fossils are commonly found in coal-bearing sedimentary rocks of Rhaetian stage from South China and the Yanchang G...Objective Neocalamites is a common plant fossil from the Triassic to the Middle Jurassic. Neocalamites fossils are commonly found in coal-bearing sedimentary rocks of Rhaetian stage from South China and the Yanchang Group from North China(Mei and Liu, 2017). Moreover, the fossils also distribute in the Late Triassic such as the Babaoshan Group in Dulan and Darigemole Group in Gangcha of Qinghai Province, the Haojiagou Formation in Turpan and the Taliqike Formation in Kuche of Xinjiang.Besides,Neocalamites fossils are also found in the Early and Middle Jurassic strata of North China.展开更多
基金supported financially by the Specialized Research Fund for the Doctoral Program of Higher Education (No.20110205110004)the National Nature Sciences Foundation of China (Nos.41472191,41172186,40972136,and 40572121)the Fundamental Research Funds for the Central Universities (Nos.CHD2011TD020,CHD2009JC046,2013G1271092,and 2013G1271091)
文摘Investigation of the petrogenesis and the origin of zircons from the volcanic rocks of the Liujiaping Group of the back-Longmenshan tectonic belt in the northwest margin of the Yangtze Block is conducted by analysis of U-Pb geochronology and geochemistry. Results show that selected zircons are characterized by internal oscillatory zonings and high Th/U ratios （0.43-1.18）, indicating an igneous origin. Geochronological results of LA-ICP-MS U-Pb dating of the Liujiaping Group zircons yield an age of 809 - 11 Ma （MSWD = 2.2）, implying that the volcanic rocks were formed in the Late Neoproterozoic. Geochemical analysis shows that the rocks are calc-alkaline, supersaturated in AI, and metaluminous to weakly peraluminous. Rare-earth elements are present at high concentrations （96.04-265.48 ppm） and show a rightward incline and a moderately negative Eu anomaly, similar to that of continental rift rhyolite. Trace element geochemistry is characterized by evident negative anomalies of Nb, Ta, P, Th, Ti, inter alia, and strong negative anomalies of K, Rb, Sr, et al. We conclude that the Liujiaping Group volcanic rocks resulted from typical continental crust source petrogenesis and were formed in a continental margin setting, which had no relation to subduction, and thus, were the products of partial melting of the lower crust due to crustal thickening caused by active continental margin subduetion and arc-continent collision orogeny in the northwestern Yangtze Block and were triggered by the breakup of the Rodinia supercontinent during the Neoproterozoic.
基金supported by the National Natural Science Foundation of China(grant No.41802234,41602229,42072267)the Fundamental Research Funds for the Central Universities,CHD(300102271207,300102279201,300102279104,300102279204)the Natural Science Foundation of Shaanxi Province,China(2019JQ-209,2019JQ-090,2019JM-312)。
文摘Objective High-pressure(HP)and ultrahigh-pressure(UHP)minerals tend to be preserved in mafic and ultramafic metamorphic rocks(e.g.eclogites and garnet amphibolite)rather than felsic rocks.Generally,HP and UHP rocks are thought to be formed as a result of the tectonic burial or subduction of oceanic crust or thicked continental lithosphere to depths corresponding to the eclogite facies metamorphism,followed by fast uplift(Ernst et al.,2007).
基金supported by the National Science Foundation of China (Grant No., 41472191, 41502191, 41172186, 40972136)the Special Fund for Basic Scientific Research of Central Colleages, Chang’an University (Grant Nos. 310827161002, 310827161006)+1 种基金the Commonweal Geological Surveythe Aluminum Corporation of China and the Land-Resources Department of Qinghai Province (Grant No., 200801)
文摘The East Kunlun Orogenic Belt(EKOB)in northeast margin of the Qinghai-Tibetan Plateau is an important part of the Central Orogenic System(COS).During the long-time geological evolution,complicated tectono
基金funded by the National Science Foundation of China (Grant Nos. 41502191, 41472191、41172186)
文摘1 Introduction East Kunlun orogen(EKO)stretching more than 1000km in E-W extension is located in the western segment of Central Orogen Belt(COB),China(Xu et al.,2006,Li et al.,2014).There outcropped Cambrian ophiolites
基金supported by the Shanghai Science and Technology Development Foundation, China (No. 08QA14035)
文摘A new near α-titanium alloy Ti12.5Zr2.5Nb2.5Ta （TZNT） for surgical implants was designed. The potentiodynamic technique was performed to investigate the corrosion behaviors of TZNT in Ringer＇s solution, and Ti6A14V, Ti6Al7Nb, and TA2 were taken as comparison. The structure of the passive film was analyzed using an X-ray photoelectron spectrometer （XPS）. The results indicate that TZNT possesses better corrosion resistance, when compared with Ti6A14V, Ti6A17Nb, and TA2. The passive film formed on the TZNT surface is composed of oxides, such as TiO2, ZrO2, Nb2O5, and Ta2O5. The elements Zr and Ta are rich, whereas Ti and Nb are poor in the passive film. The addition of Zr, Nb, and Ta with relatively low electrochemical reaction potentials can reduce the anode activity and improve passive properties. Other than that, oxides such as ZrO2, Nb2O5, and Ta2O5 with the nobler equilibrium constants make the passive film more stable.
基金supported financially by the National Nature Sciences Foundation of China (grants No. 41872233, 41872235, 41802234, 41472191, 41502191, 41172186, 40972136)China Geological Survey (grants No. 12120114041201, DD2016007901)+2 种基金China Scholarship Council (grant No. 201806565026)China Postdoctoral Science Foundation (2016M592726)the Fundamental Research Funds for the Central Universities(grants No. 300103183081, 300104282717, 300102279204, 201810710233)
文摘Objective Neocalamites is a common plant fossil from the Triassic to the Middle Jurassic. Neocalamites fossils are commonly found in coal-bearing sedimentary rocks of Rhaetian stage from South China and the Yanchang Group from North China(Mei and Liu, 2017). Moreover, the fossils also distribute in the Late Triassic such as the Babaoshan Group in Dulan and Darigemole Group in Gangcha of Qinghai Province, the Haojiagou Formation in Turpan and the Taliqike Formation in Kuche of Xinjiang.Besides,Neocalamites fossils are also found in the Early and Middle Jurassic strata of North China.
