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| 1 | Geochronology, geochemistry, and Sr-Nd isotopes of Early Carboniferous magmatism in southern West Junggar, northwestern China: Implications for Junggar oceanic plate subduction显示文摘West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of the Junggar Ocean.Knowledge of the Carboniferous tectonic evolution of the Junggar Ocean region is required for understanding the tectonic framework and accretionary processes in West Junggar,Central Asian Orogenic Belt.A series of Early Carboniferous volcanic and intrusive rocks,namely,basaltic andesite,andesite,dacite,and diorite,occur in the Mayile area of southern West Junggar,northwestern China.Our new LA-ICPMS zircon U-Pb geochronological data reveal that diorite intruded at 334(±1)Ma,and that basaltic andesite was erupted at 334(±4)Ma.These intrusive and volcanic rocks are calc-alkaline,display moderate MgO(1.62%-4.18%)contents and Mg#values(40-59),and low Cr(14.5×10-6-47.2×10-6)and Ni(7.5×10-6-34.6×10-6)contents,and are characterized by enrichment in light rare-earth elements and large-ion lithophile elements and depletion in heavy rare-earth elements and high-field-strength elements,meaning that they belong to typical subduction-zone island-arc magma.The samples show low initial 87Sr/86Sr ratios(range of 0.703649-0.705008),positiveεNd(t)values(range of 4.8-6.2 and mean of 5.4),and young TDM Nd model ages ranging from 1016 to 616 Ma,indicating a magmatic origin from depleted mantle involving partial melting of 10%-25%garnet and spinel lherzolite.Combining our results with those of previous studies,we suggest that these rocks were formed as a result of northwestward subduction of the Junggar oceanic plate,which caused partial melting of sub-arc mantle.We conclude that intra-oceanic arc magmatism was extensive in West Junggar during the Early Carboniferous. | LIU Pengde LIU Xijun XIAO Wenjiao ZHANG Zhiguo SONG Yujia XIAO Yao LIU Lei HU Rongguo WANG Baohua | 2021 | Journal of Arid Land2021，13，11： | 1 |
| 2 | The use of external fixation combined with vacuum sealing drainage to treat open comminuted fractures of tibia in the Wenchuan earthquake显示文摘 | Lei Liu Gang Tan Fujun Luan Xin Tang Pengde Kang Chongqi Tu Fuxing Pei | 2012 | International Orthopaedics2012，，7： | 1 |
| 3 | Origin of the DUPAL anomaly in the Tethyan mantle domain and its geodynamic significance显示文摘Mantle heterogeneity has revealed systematic differences in Pb isotopic compositions between the Indian OceanSouth Atlantic mantle in the Southern Hemisphere and the Pacific Ocean-North Atlantic mantle in the Northern Hemisphere.This large-scale difference in mantle isotopes in the Southern Hemisphere is known as the DUPAL anomaly,but its origin remains controversial.Based on a systematic review of the Nd-Pb isotopic evolution of the Tethyan mantle domain,this study identified the long-term presence of the DUPAL anomaly in this domain since the early Paleozoic,characterized by long-term and high mantle thorium/uranium(Th/U)ratios.By comparing the Nd-Pb isotopic compositions of the Tethyan mantle domain with the Panthalassic-Pacific mantle domain(the Paleo-Asian,Paleo-Pacific,and modern Pacific oceans),it is shown that the mantle initially had low Th/U features due to early Earth crust-mantle differentiation,with the crust having high Th/U ratios.As such,the mantle initially had uniformly low Th/U ratios that were inherited throughout the Panthalassic-Pacific mantle domain.However,the plate tectonics and continental collisions in the Tethyan domain affected its characteristics,leading to the long-term and large-scale DUPAL anomaly.During the opening of and subduction in the Tethys Ocean,Gondwanaland fragmentation and frequent continent-continent collisions led to long-term and extensive crust-mantle interactions and the continuous input of highTh/U mantle sources,which thus modified the mantle.This process formed not only the unique DUPAL anomaly in the Tethyan mantle domain,but also the Tethyan tectonic domain dominated by continental collisions.Moreover,the high DUPAL anomaly in the Proto-and Paleo-Tethyan mantle domains records the effects of mantle plumes,which might have occurred primarily during the formation of the Proto-and Paleo-Tethys oceans during the early evolution of the Tethyan domain.Therefore,the inherent coupling of mantle domain properties and plate tectonic mechanisms provides important insights for understanding plate tectonics and geodynamic processes in the Tethyan domain. | Xijun LIU Jifeng XU Wenjiao XIAO Pengde LIU | 2023 | Science China Earth Sciences2023，66，12： | 0 |
| 4 | Hot subduction in the southern Paleo-Asian Ocean:Insights from clinopyroxene chemistry and Sr-Nd-Hf-Pb isotopes of Carboniferous volcanics in West Junggar显示文摘The chemical evolution and pressure-temperature conditions of subduction zone magmatism along ancient suture zones in orogenic belts can provide important information regarding plate convergence processes in paleo-oceans.Carboniferous magmatism in West Junggar is key to understanding the tectonothermal and subduction history of the Junggar Ocean,which was a branch of the Paleo-Asian Ocean,as well as the accretionary processes in the southwestern Central Asian Orogenic Belt(CAOB).We undertook a geochronological,mineralogical,geochemical,and Sr-Nd-Hf-Pb isotopic study of volcanic rocks from the Baikouquan area of West Junggar.We used these data to determine the petrogenesis,mantle source,and pressure-temperature conditions of these magmas,and further constrain the subduction and tectonic history of the Junggar Ocean.The studied volcanic rocks yielded zircon U-Pb ages of 342-337 Ma and are characterized by enrichments of large-ion lithophile elements(LILEs),and depletions in high-field-strength elements(HFSEs),indicative of an island arc affinity.The volcanic rocks have positiveƐNd(t)(5.83-7.04)andƐHf(t)(13.47-15.74)values,87Sr/86Sr(t)ratios of 0.704023-0.705658,and radiogenic 207Pb/204Pb(t)and 208Pb/204Pb(t)ratios at a given 206Pb/204Pb(t)ratio,indicative of a depleted mantle source contaminated by subduction-related materials.Geochemical modeling calculations indicate that≤1%of a subduction component comprising fluid and sediment melt could have generated the source of the parental melts of the Baikouquan volcanic rocks.Clinopyroxene phenocrysts in the volcanic rocks are classified as high-and low-Ti clinopyroxene,and pressure-temperature calculations suggest the host rocks formed at high temperatures(~1300℃)and shallow to moderate depths(<2 GPa).The magma was probably generated by hot and hydrous melting in a mantle wedge in response to subduction of young,hot oceanic lithosphere.The present results,combined with published data,suggest that the Baikouquan volcanic rocks record a transition in tectonic setting from normal cold to anomalous hot subduction of young oceanic lithosphere close to a mid-ocean ridge.This indicates ridge subduction began shortly after 337 Ma.Our results provide new insights into the tectonomagmatic evolution during intra-oceanic subduction prior to ridge subduction. | Yao Xiao Xijun Liu Wenjiao Xiao Xiao-Han Gong Hao Wu Yujia Song Zhiguo Zhang Pengde Liu | 2024 | Geoscience Frontiers2024，15，1： | 0 |
| 5 | Neoproterozoic I-type granites in the Central Tianshan Block (NW China):geochronology,geochemistry,and tectonic implications显示文摘The Central Tianshan Block is one of numerous microcontinental blocks within the Central Asian Orogenic Belt(CAOB)that overlies Precambrian basement rocks.Constraining the evolution of these ancient basement rocks is central to understanding the accretionary and collisional tectonics of the CAOB,and their place within the Rodinia supercontinent.However,to date,the timing and tectonic settings in which the basement rocks in the Central Tianshan Block formed are poorly constrained,with only sparse geochemical and geochronological data from granitic rocks within the northern segment of the block.Here,we present a systematic study combining U-Pb geochronology,whole-rock geochemistry,and the Sr-Nd isotopic compositions of newly-identified granitic gneisses from the Bingdaban area of Central Tianshan Block.The analyzed samples yield a weighted mean Neoproterozoic 206Pb/238U ages of 975-911 Ma.These weakly-peraluminous granitic rocks show a common geochemical I-type granite affinity.The granitic gneisses are calc-alkaline and enriched in large ion lithophile elements(LILEs)and light rare earth elements(LREEs),but they are depleted in high field strength elements(HFSEs);these characteristics are similar to those of typical subduction-related magmatism.All samples show initial(^(87)Sr/^(86)Sr)(t)ratios between 0.705136 and 0.706745.Values forεNd(t)in the granitic gneisses are in the range from-5.7 to-1.2,which correspond to Nd model ages of 2.0-1.7 Ga,indicating a role for Mesoproterozoic to Paleoproterozoic rocks in the generation of the granitic protoliths.The documented geochemical features indicate that the protoliths for the gneisses have a similar petrogenesis and magmatic source,which may reflect partial melting of thickened crust with the addition of small amounts of mantle-derived material.The Central Tianshan Block probably constitute part of an exterior orogen that developed along the margin of the Rodinian supercontinent during the Early Neoproterozoic and underwent a transition from subduction to syn-collision compression at 975-911 Ma. | SONG Yujia LIU Xijun XIAO Wenjiao ZHANG Zhiguo LIU Pengde XIAO Yao LI Rui WANG Baohua LIU Lei HU Rongguo | 2022 | Journal of Arid Land2022，14，1： | 0 |
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