9 results on '"Weidong Sun"'
Search Results
2. Newly discovered Late Triassic Baqing eclogite in central Tibet indicates an anticlockwise West–East Qiangtang collision
- Author
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Li-Long Yan, Jian-Ming Liu, Xin Jin, Kai-Jun Zhang, Yu-Xiu Zhang, Xiao-Yao Zhou, and Weidong Sun
- Subjects
Multidisciplinary ,010504 meteorology & atmospheric sciences ,Subduction ,Metamorphic core complex ,Metamorphic rock ,lcsh:R ,Geochemistry ,lcsh:Medicine ,010502 geochemistry & geophysics ,01 natural sciences ,Article ,Tectonics ,lcsh:Q ,Suture (geology) ,Eclogite ,lcsh:Science ,Cenozoic ,Geology ,0105 earth and related environmental sciences ,Petrogenesis - Abstract
The Triassic eclogite-bearing central Qiangtang metamorphic belt (CQMB) in the northern Tibetan Plateau has been debated whether it is a metamorphic core complex underthrust from the Jinsha Paleo-Tethys or an in-situ Shuanghu suture. The CQMB is thus a key issue to elucidate the crustal architecture of the northern Tibetan Plateau, the tectonics of the eastern Tethys, and the petrogenesis of Cenozoic high-K magmatism. We here report the newly discovered Baqing eclogite along the eastern extension of the CQMB near the Baqing town, central Tibet. These eclogites are characterized by the garnet + omphacite + rutile + phengite + quartz assemblages. Primary eclogite-facies metamorphic pressure–temperature estimates yield consistent minimum pressure of 25 ± 1 kbar at 730 ± 60 °C. U–Pb dating on zircons that contain inclusions (garnet + omphacite + rutile + phengite) gave eclogite-facies metamorphic ages of 223 Ma. The geochemical continental crustal signature and the presence of Paleozoic cores in the zircons indicate that the Baqing eclogite formed by continental subduction and marks an eastward-younging anticlockwise West–East Qiangtang collision along the Shuanghu suture from the Middle to Late Triassic.
- Published
- 2018
3. Survey of Antithrombotic Treatment in Rural Patients (60 years) with Atrial Fibrillation in East China
- Author
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Genqing Zhou, Yahong Shen, Shaowen Liu, Songwen Chen, Caihong Wang, Haiqing Wu, Juan Xu, Jianping Sun, Zheng He, Bin Wang, Shunhong Yang, Yong Wei, Weidong Sun, and Ping Ouyang
- Subjects
Male ,Rural Population ,medicine.medical_specialty ,China ,Delayed Diagnosis ,medicine.drug_class ,Science ,030204 cardiovascular system & hematology ,Statistics, Nonparametric ,Article ,03 medical and health sciences ,0302 clinical medicine ,Sex Factors ,Fibrinolytic Agents ,Internal medicine ,Antithrombotic ,Atrial Fibrillation ,Prevalence ,Medicine ,Humans ,030212 general & internal medicine ,Stroke ,Aged ,Aged, 80 and over ,Aspirin ,Analysis of Variance ,Multidisciplinary ,Chi-Square Distribution ,business.industry ,Anticoagulant ,Warfarin ,Age Factors ,Anticoagulants ,Atrial fibrillation ,Middle Aged ,medicine.disease ,Clopidogrel ,Thrombosis ,Health Surveys ,Treatment Adherence and Compliance ,Treatment Outcome ,Female ,business ,medicine.drug - Abstract
The prevalence and antithrombotic treatment of atrial fibrillation (AF) in Chinese rural population is not well known. The aim of this study was to investigate the extent to which antithrombotic treatment was prescribed for rural AF patients >60 years. We identified 828 AF patients from 36734 rural residents >60 years in Shanghai China. Our data indicated the overall prevalence rate of AF was 2.3% in rural population >60 years in East China and 38.9% of AF patients underwent antithrombotic therapy, including warfarin (5.9%), aspirin (29.6%), clopidogrel (2.9%) and aspirin combined with clopidogrel (0.5%). Of enrolled subjects, 98.4% had CHA2DS2-VASc score ≥1, 72.0% had HAS-BLED score 2DS2-VASc score ≥2 with HAS-BLED score
- Published
- 2016
4. The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures
- Author
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Xing Ding, Weidong Sun, Wenhuan Zhan, Shaobang Peng, Jinzhong Liu, and Ruifang Huang
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Abiotic component ,Peridotite ,Metabolic energy ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,Hydrogen molecule ,chemistry.chemical_element ,010502 geochemistry & geophysics ,Critical value ,01 natural sciences ,Article ,Methane ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Carbon dioxide ,Carbon ,0105 earth and related environmental sciences - Abstract
Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H2) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H2/CH4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately larger than 40 for abiotic methane and values of 2/CH4 ratios strongly depend on temperature. At 311 °C and 3.0 kbar, the H2/CH4 ratios ranged from 58 to 2,120, much greater than the critical value of 40. By contrast, at 400–500 °C, the H2/CH4 ratios were much lower, ranging from 0.1 to 8.2. The results of this study suggest that the H2/CH4 ratios cannot reliably discriminate abiotic from biotic methane.
- Published
- 2016
- Full Text
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5. Origin of the mysterious Yin-Shang bronzes in China indicated by lead isotopes
- Author
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Weidong Sun, Zhaofeng Zhang, Robert E. Zartman, Jia Guo, Lipeng Zhang, Yuhang Jiang, and Congying Li
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Isochron ,geography ,Multidisciplinary ,Radiogenic nuclide ,geography.geographical_feature_category ,060102 archaeology ,Isotope ,Archean ,Geochemistry ,Central china ,06 humanities and the arts ,010502 geochemistry & geophysics ,01 natural sciences ,Article ,Craton ,Lead (geology) ,Smelting ,0601 history and archaeology ,Geology ,0105 earth and related environmental sciences - Abstract
Fine Yin-Shang bronzes containing lead with puzzlingly highly radiogenic isotopic compositions appeared suddenly in the alluvial plain of the Yellow River around 1400 BC. The Tongkuangyu copper deposit in central China is known to have lead isotopic compositions even more radiogenic and scattered than those of the Yin-Shang bronzes. Most of the Yin-Shang bronzes are tin-copper alloys with high lead contents. The low lead and tin concentrations, together with the less radiogenic lead isotopes of bronzes in an ancient smelting site nearby, however, exclude Tongkuangyu as the sole supplier of the Yin-Shang bronzes. Interestingly, tin ingots/prills and bronzes found in Africa also have highly radiogenic lead isotopes, but it remains mysterious as to how such African bronzes may have been transported to China. Nevertheless, these African bronzes are the only bronzes outside China so far reported that have lead isotopes similar to those of the Yin-Shang bronzes. All these radiogenic lead isotopes plot along ~2.0–2.5 Ga isochron lines, implying that deposits around Archean cratons are the most likely candidates for the sources. African cratons along the Nile and even micro-cratons in the Sahara desert may have similar lead signatures. These places were probably accessible by ancient civilizations and thus are the most favorable suppliers of the bronzes.
- Published
- 2016
- Full Text
- View/download PDF
6. A ‘hidden’ 18O-enriched reservoir in the sub-arc mantle
- Author
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Sun-Lin Chung, Weidong Sun, Fu-Yuan Wu, Wei-Qiang Ji, Chuan-Zhou Liu, and Qiu-Li Li
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geography ,Geologic Sediments ,Multidisciplinary ,geography.geographical_feature_category ,Volcanic arc ,Mantle wedge ,Earth, Planet ,Crustal recycling ,Silicates ,Magnesium Compounds ,Oxygen Isotopes ,Mantle (geology) ,Article ,Mantle convection ,Hotspot (geology) ,Transition zone ,Petrology ,Planetary differentiation ,Geology ,Iron Compounds - Abstract
Plate subduction continuously transports crustal materials with high-δ18O values down to the mantle wedge, where mantle peridotites are expected to achieve the high-δ18O features. Elevated δ18O values relative to the upper mantle value have been reported for magmas from some subduction zones. However, peridotites with δ18O values significantly higher than the well-defined upper mantle values have never been observed from modern subduction zones. Here we present in-situ oxygen isotope data of olivine crystals in Sailipu mantle xenoliths from South Tibet, which have been subjected to a long history of Tethyan subduction before the India-Asia collision. Our data identify for the first time a metasomatized mantle that, interpreted as the sub-arc lithospheric mantle, shows anomalously enriched oxygen isotopes (δ18O = +8.03 ± 0.28 ‰). Such a high-δ18O mantle commonly does not contribute significantly to typical island arc basalts. However, partial melting or contamination of such a high-δ18O mantle is feasible to account for the high-δ18O signatures in arc basalts.
- Published
- 2014
7. Mysterious abrupt carbon-14 increase in coral contributed by a comet
- Author
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Kexin Liu, Yi Liu, Zicheng Peng, Weiguo Liu, Xiao-chun Sun, Chengde Shen, Weidong Sun, Zhaofeng Zhang, Ming-Xing Ling, and Chuan-Chou Shen
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China ,Multidisciplinary ,South china ,Coral ,Comet ,chemistry.chemical_element ,Cosmic ray ,Biology ,Atmospheric sciences ,Anthozoa ,Nitrogen ,Article ,law.invention ,Atmosphere ,chemistry ,law ,Animals ,Carbon-14 ,Radiocarbon dating ,Carbon Radioisotopes ,Cosmic Radiation - Abstract
A large and sudden increase in radiocarbon (14C) around AD 773 are documented in coral skeletons from the South China Sea. The 14C increased by ~ 15‰ during winter and remain elevated for more than 4 months, then increased and dropped down within two months, forming a spike of 45‰ high in late spring, followed by two smaller spikes. The 14C anomalies coincide with an historic comet collision with the Earth's atmosphere on 17 January AD 773. Comas are known to have percent-levels of nitrogen by weight and are exposed to cosmic radiation in space. Hence they may be expected to contain highly elevated 14C/12C ratios, as compared to the Earth's atmosphere. The significant input of 14C by comets may have contributed to the fluctuation of 14C in the atmosphere throughout the Earth's history, which should be considered carefully to better constrain the cosmic ray fluctuation.
- Published
- 2013
8. Isotopic evidence for continental ice sheet in mid-latitude region in the supergreenhouse Early Cretaceous
- Author
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He-Cai Niu, Congying Li, Qiang Shan, Weidong Sun, Yong-Fei Zheng, Yuhang Jiang, Ning-Bo Li, Nicholas Arndt, Xing Xu, Wu-Bin Yang, and Xueyuan Yu
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geography ,Multidisciplinary ,geography.geographical_feature_category ,Aptian ,Glacier ,Article ,Cretaceous ,Paleontology ,Meteoric water ,Fluid inclusions ,Glacial period ,Ice sheet ,Geology ,Zircon - Abstract
Cretaceous represents one of the hottest greenhouse periods in the Earth's history, but some recent studies suggest that small ice caps might be present in non-polar regions during certain periods in the Early Cretaceous. Here we report extremely negative δ(18)O values of -18.12‰ to -13.19‰ for early Aptian hydrothermal zircon from an A-type granite at Baerzhe in northeastern China. Given that A-type granite is anhydrous and that magmatic zircon of the Baerzhe granite has δ(18)O value close to mantle values, the extremely negative δ(18)O values for hydrothermal zircon are attributed to addition of meteoric water with extremely low δ(18)O, mostly likely transported by glaciers. Considering the paleoaltitude of the region, continental glaciation is suggested to occur in the early Aptian, indicating much larger temperature fluctuations than previously thought during the supergreenhouse Cretaceous. This may have impact on the evolution of major organism in the Jehol Group during this period.
- Published
- 2013
- Full Text
- View/download PDF
9. Mysterious abrupt carbon-14 increase in coral contributed by a comet.
- Author
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Yi Liu, Zhao-feng Zhang, Zi-cheng Peng, Ming-xing Ling, Chuan-Chou Shen, Wei-guo Liu, Xiao-chun Sun, Cheng-de Shen, Ke-xin Liu, and Weidong Sun
- Subjects
RADIOCARBON dating ,CARBON isotopes ,IMPACT of comets on Earth ,COSMIC rays ,ATMOSPHERE - Abstract
A large and sudden increase in radiocarbon (
14 C) aroundAD773 are documented in coral skeletons from the South China Sea. The14 C increased by ~15%during winter, and remain elevated for more than 4 months, then increased and dropped down within two months, forming a spike of 45%high in late spring, followed by two smaller spikes. The14 C anomalies coincide with an historic comet collision with the Earth's atmosphere on 17 January AD 773. Comas are known to have percent-levels of nitrogen by weight, and are exposed to cosmic radiation in space. Hence they may be expected to contain highly elevated14 C/12 C ratios, as compared to the Earth's atmosphere. The significant input of14 C by comets may have contributed to the fluctuation of14 C in the atmosphere throughout the Earth's history, which should be considered carefully to better constrain the cosmic ray fluctuation. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
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