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Detrital Zircon Geochronology of Early Triassic Strata in the West Qinling Orogen:Implications for the Tectonic Evolution of the Paleo-Tethyan Ocean

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Journal of Earth Science 2024年第4期35卷 1087-1106页

作者： Zuochen li Xianzhi Pei liyong Wei Guobing liang Meng Wang ruibao li Lei Pei Chengjun liu Youxin Chen Feng Gao Xi’an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals School of Earth Science and ResourcesChang’an UniversityXi’an710054China Xi’an Mineral Resources Survey Center China Geological SurveyXi’an710100China School of Geology and Mining Engineering Xinjiang UniversityUrumqi830000China

The West Qinling Orogen(WQO)is located in the western part of the Qinling Orogen and in the transition zone of Qilian Orogen,Songpan-Garze Orogen and Yangtze Block,and also the key position of Triassic collision orogenic *** study of the Early Triassic strata in the WQO is contributed to analyze the closure process of the *** conducted LA-ICP-MS U-Pb dating studies on detrital zircons to determine the provenance,depositional age,and tectonic setting of the Early Triassic Longwuhe Formation in the lintan area of the *** results show that the majority of the detrital zircons in the Longwuhe Formation are mainly magmatic origin and have characteristic of crust source *** lowest limit of sedimentation of the Longwuhe Formation is constrained to the Early Triassic,with the youngest detrital zircon age of 253±3 *** ages can be divided into five age groups:3346–1636 Ma,with two peak ages of ca.2495 and ca.1885 Ma;1585–1010 Ma,with a peak age at ca.1084 Ma;992–554 Ma,with a peak age at ca.939 Ma;521–421 Ma,with a peak age at ca.445 Ma;418–253 Ma,with a peak age at ca.280 ***,the sources of the Longwuhe Formation include the northern margin of the WQO,the Qilian Orogen(QLO)and the basement of the southern margin of the North China Block(NCB),of which the ancient basement of the southern margin of the NCB is the main source area of the Longwuhe *** with previous studies,we propose that the Longwuhe Formation was formed in a fore-arc basin,which is related to the closure of the A’nyemaqen-Mianlüe Ocean from the Early Permian to Early–Middle Triassic due to the northward subduction-collision of the Yangtze Block(YZB).This also indicates that the A’nyemaqen-Mianlüe Ocean has flat subduction characteristics.

关键词： West Qinling orogenic belt Early Triassic paleo-Tethyan Ocean geochronology zircon

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抗战时期师范教育课程体系探析——基于“主体-客体”因素的评价

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教育与考试 2024年第5期 72-78页

作者：李瑞宝唐蜜福建省教育考试院福州350003 四川司法警官职业学院刑事司法系德阳618000

抗战时期的师范教育虽受日军破坏严重,但却在教育部“战时需作平时看”方针的指引下得以重建,并为此后中国师范教育发展提供了深刻的经验与启示。本文结合泰勒的行为目标导向课程评价模式及施瓦布的课程要素理论,提出“主体—客体”课... 详细信息

抗战时期的师范教育虽受日军破坏严重,但却在教育部“战时需作平时看”方针的指引下得以重建,并为此后中国师范教育发展提供了深刻的经验与启示。本文结合泰勒的行为目标导向课程评价模式及施瓦布的课程要素理论,提出“主体—客体”课程评价要素,对战时师范教育课程体系进行分析。在“五育并举”教育目标的指引下,战时师范教育课程体系呈现出高强度、高标准、多样化的教学特征。一方面,学生通过教师层层深入式的专业规训以及多元教学材料的运用,成长为专业性强的全面型预备教师,大大缓解此时国内的“师荒”现状。另一方面,严格的课程考核使得战时师范课程呈现出高压性与同化性,不利于学生的心理健康与个性化发展。

关键词：抗战时期师范教育课程 “主体-客体”因素

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雅鲁藏布江中段日喀则地区却顶布—路曲地幔橄榄岩岩石地球化学特征、成因及其地质意义

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地学前缘 2024年第3期31卷 1-19页

作者：陈国超张晓飞裴先治裴磊李佐臣刘成军李瑞保南阳理工学院土木工程学院河南南阳473000 长安大学地球科学与资源学院陕西西安710054 自然资源部成矿作用与资源评价重点实验室北京100037 中国地质调查局发展研究中心北京100037

日喀则蛇绿岩是雅鲁藏布江缝合带的重要组成部分,但是对该蛇绿岩的成因和构造背景还存在较大的争议。本文以日喀则地区却顶布—路曲蛇绿岩为研究对象,通过详细的野外地质、岩石学、矿物化学及岩石地球化学研究,显示该蛇绿岩主要由方辉... 详细信息

日喀则蛇绿岩是雅鲁藏布江缝合带的重要组成部分,但是对该蛇绿岩的成因和构造背景还存在较大的争议。本文以日喀则地区却顶布—路曲蛇绿岩为研究对象,通过详细的野外地质、岩石学、矿物化学及岩石地球化学研究,显示该蛇绿岩主要由方辉橄榄岩组成,另有少量辉长岩、辉绿岩和玄武岩。与路曲方辉橄榄岩相比,却顶布方辉橄榄岩中橄榄石的Fo值较低,斜方辉石Al_(2)O_(3)和Cr_(2)O_(3)含量较高,单斜辉石Al_(2)O_(3)含量和Cr#值较高,尖晶石Cr#值和TiO_(2)含量较低。却顶布—路曲方辉橄榄岩具有较高的MgO含量和较低的Al_(2)O_(3)、CaO、TiO_(2)含量,稀土元素总量为(0.17~1.63)×10^(-6),低于原始地幔和亏损地幔。路曲方辉橄榄岩的LREE/HREE和(La/Yb)_(N)比值较高,分别为1.34~9.22和0.56~12.14;却顶布方辉橄榄岩与其相反,LREE/HREE和(La/Yb)_(N)比值分别为0.29~0.81和0.11~0.25。路曲方辉橄榄岩呈轻稀土富集型的U型稀土元素配分模式;却顶布方辉橄榄岩为轻稀土亏损型的左倾型稀土元素配分模式。路曲方辉橄榄岩和却顶布方辉橄榄岩具有近似的微量元素分布特征,但是又有一定区别,路曲方辉橄榄岩大离子亲石元素Rb、Ba高于却顶布方辉橄榄岩,但K、Sr低于却顶布方辉橄榄岩。却顶布—路曲方辉橄榄岩的源区可能来源于地幔中的尖晶石相二辉橄榄岩。却顶布—路曲方辉橄榄岩矿物化学和全岩地球化学特征与深海地幔橄榄岩相似。矿物学和全岩岩石地球化学特征显示却顶布方辉橄榄岩为经历了10%~15%部分熔融的残余,路曲方辉橄榄岩为经历了20%~25%部分熔融的残余。却顶布—路曲方辉橄榄岩形成于慢速超慢速拉张的洋中脊环境。日喀则蛇绿岩的多样性与源区部分熔融程度和后期流体交代密切相关。

关键词：雅鲁藏布江缝合带却顶布—路曲蛇绿岩地幔橄榄岩岩石成因

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Accretion Processes of Oceanic Crust in Slow-spreading Ridges:Plagiogranite Perspective of the Xigaze Ophiolite,South Tibet

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Acta Geologica Sinica(English Edition) 2022年第6期96卷 1945-1959页

作者： li Yuan li ruibao YANG Shengbiao ZHANG Jian YANG Jingsui Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China School of Earth Sciences and Resources Chang’an UniversityXi’an 710054China Tianjin Institute of Geology and Mineral Resources Tianjing 300170China School of Earth Sciences and Engineering Nanjing UniversityNanjing 210023China

Structural and petrological data suggest that the Xigaze ophiolite from the Yarlung Zangbo Suture Zone(YZSZ)in south Tibet was a typical slow-spreading ridge.A new field,geochemical,mineral,and U-Pb zircon dataset of plagiogranite intrusions were used to constrain the dynamic processes of oceanic accretion in this slow-spreading *** mainly occur as dykes or intrusions intruded into the whole sequence of the ophiolite and have a similar orientation to the dolerite dykes developed in the late stage of detachment faulting.U-Pb zircon ages of 122–123 Ma were obtained for two types of plagiogranites and associated dolerite *** geochemical and mineralogical examinations suggest that the plagiogranites are the product of low-pressure(2–3 kbar)fractional crystallization of midocean ridge basalt-like magma and unlikely to have been derived from the partial melting of hydrous gabbroic *** complex cross-cut relationship between the plagiogranites and ophiolite sequence reflects that they are controlled by small discontinued melt lenses rather than a big magma chamber under the ridge axis and reveals multiple injections during the oceanic crust *** formation of plagiogranites possibly reflects the complex characteristic of oceanic accretion at slow-spreading ridges,time-dependent on structural(external)and magmatic(internal)processes.

关键词： Xigaze ophiolite plagiogranite fractional crystallization multiple magma injection ocean-continent transition zone

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The Boninite-like Dolerites in the Xigaze Ophiolites, Tibet: Similar to the MORB-like Dolerites

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Acta Geologica Sinica(English Edition) 2020年第S1期94卷 73-75页

作者： YANG Shengbiao YANG Jingsui li Yuan li ruibao Center for Advanced Research on the Mantle(CARMA) Key Laboratory of Deep-Earth Dynamics of Ministry of Land and ResourcesInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037 School of Earth Sciences and Resources Chang’an UniversityXi’anShaanxi 710054

The Early Cretaceous Xigaze ophiolites(XO)exposed along the central segment of the more than 2000 km long Yarlung Zangbo Suture Zone in southern Tibet,preserved the structure of the upper mantle and oceanic crust,is interpreted as a definite record of Neo-Tethys oceanic *** evolution models of the XO have been proposed since the 1980s(Nicolas et al.,1981;Hébert et al.,2012;Maffione et al.,2015).However,the geodynamic environment of the XO whether at a MOR or SSZ remains *** key evidence for the identification of the SSZ ophiolite,the boninite-like dolerites from the XO are still controversial and poorly constraint(Chen et al.,2003;Bao et al.,2013;Dai et al.,2013).According to previous reports,dolerites were subdivided to MORB-like type and boninite-like type(Chen et al.,2003;Dai et al.,2013).Apart from high-SiO2(>52 wt%),high MgO(>8 wt%)and low-TiO2(like and MORB-like dolerites are indistinguishable in outcrop,mineral and *** are sills invaded into mantle sequence of the XO,with 50.35–56.80 wt%SiO2,0.32–1.19 wt%TiO2,7.39–8.89 wt%Fe2O3T,5.50–10.42 wt%MgO and Mg#of 0.49–***-like dolerites display trace element and REE patterns similar to those of most fore-arc or/and back-arc basalts from Izu-Bonin-Mariana(IBM),*** in large ion lithophile elements(liLEs,***,Rb,Ba,Pb,U)and depletion in high-field strength elements(HFSE,Nb,Ta)(Fig.1).Boninite-like dolerites resemble the MORB-like dolerites in trace elements and REE patterns,excepting for lower concentrations in REE,but distinct from the boninites discovered from the IBM or Troodos ophiolite(Fig.1c,d).Th in both dolerites deviate from the MORB array with negative slopes on the Th/Yb ***/Yb diagram(Fig.2a),suggesting constant subduction component added to the mantle source(Pearce et al.,1995).We chose depleted MORB source Mantle(DMM,Workman and Hart,2005)as the starting composition computing immobile element contents for primary melt

关键词： Yarlung Zangbo suture zone Xigaze ophiolite depleted mantle mid-ocean ridge

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Geochemical Features, Age, and Tectonic Significance of the Kekekete Mafic-ultramafic Rocks, East Kunlun Orogen, China

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Acta Geologica Sinica(English Edition) 2013年第5期87卷 1319-1333页

作者： li ruibao PEI Xianzhi li Zuochen SUN Yu FENG Jianyong PEI Lei CHEN Guochao liU Chengjun CHEN Youxin Key Laboratory of Western China’s Mineral Resources and Geological Engineering Ministry of Education School of Earth Science and Resources Chang’an University National Key Laboratory of Remote Sensing Information and Image Analysis Technology Beijing Research Institute of Uranium Geology Institute of Geology and Geophysics CAS School of Earth Science and Resources China University of Geosciences

The Kekekete mafic-ultramafic rocks are exposed in the Kekesha-Kekekete-Dawate area, which are in the eastern part of the East Kunlun Orogenic Belt. It outcrops as tectonic slices intruding tectonically in the Paleoproterozoic Baishahe Group and the Paleozoic Nachitai Group. The Kekekete mafic and ultramafic rocks is located near the central fault in East Kunlun and lithologically mainly consists of serpentinite, augite peridotite, and gabbro. The LA-ICP-MS zircon U-Pb age of the gabbro is 501±7 Ma, indicating that Kekekete mafic-ultramafic rocks formed in the Middle Cambrian. This rock assemblage is relatively poor in SiO2 and （Na20＋K20） but rich in MgO and SFeO. The chondrite-normalized REE patterns of the gabbro dip slightly to the right; the primitive mantle and MORB-normalized spidergrams of trace elements show enrichment of large-ion lithophile elements （Cs, Rb, Ba, etc.） and no differentiation of high field strength elements. The general dominance of E- MORB features and the geochemical characteristics of OIB suggest that the Kekekete mafic- ultramafic rocks formed in an initial oceanic basin with slightly enriched mantle being featured by varying degrees of mixing of N-MORB depleted mantle and a similar-OIB-type source. From a comprehensive study of the previous data, the author believes that the tectonic history of the East Kunlun region was controlled by a geodynamic system of rifting and extension in the late stages of the Neoproterozoic to early stages of the Early Paleozoic and this formed the paleo-oceanic basin or rift system now represented by the ophiolites along the central fault in East Kunlun, the Kekekete mafic- ultramafic rocks and Delisitan ophiolite.

关键词： ophiolite tectonic attribute Kekekete East Kunlun Orogeny

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Paleo-Tethyan Oceanic Crust Subduction in the Eastern Section of the East Kunlun Orogenic Belt:Geochronology and Petrogenesis of the Qushi'ang Granodiorite

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Acta Geologica Sinica(English Edition) 2017年第2期91卷 565-580页

作者： CHEN Guochao PEI Xianzhi li ruibao li Zuochen liU Chengjun CHEN Youxin PEI Lei WANG Meng li Xiaobing Key Laboratory of Western China's Mineral Resources and Geological Engineering Ministry of EducationKey Laboratory for the study of Focused Magmatism and Giant Ore DepositsMLRFaculty of Earth Science and Resources Chang'an University Nanyang Institutte of Technolog School of Civil Engineeringy School of Earth Science and Resource China University of Geosciences Shanxi Normal University College of Geographical Sciences

The Qushi’ang granodiorite（QSG） is located at the central east of the ophiolitic melange belt in the East Kunlun Orogenic Belt（EKOB） in the northern margin of the Qinghai-Tibetan Plateau. LA-MC-ICP-MS zircon U–Pb dating suggests that the granodiorite and mafic microgranular enclaves（MMEs） crystallized 246.61±0.62 and 245.45±0.9 Ma ago, respectively. Granodiorite, porphyritic diorite, and MMEs are metaluminous and medium-K calk-alkaline series, with island-arc magma features, such as liLE enrichment and HFSE depletion. The porphyritic diorite has high Cr（13.50 ppm to 59.01 ppm）, Ni（228.53 ppm to 261.29 ppm）, and Mg~#（46–54）. Granodiorite and porphyritic diorite have similar mineral compositions and evolved major and trace elements contents, particularly Cr and Ni, both of which are significantly higher than that in granites of the same period. The crystallization age of MMEs is close to that of granodiorite, and their major and trace elements contents are in-between porphyritic diorite and granodiorite. The results suggest that the original mafic magma, which was the product of mantle melting by subduction process, intruded into the lower crust（Kuhai Rock Group）, resulting in the formation of granodiorite. Countinous intrusion of mafic magma into the unconsolidated granodiorite formed MMEs and porphyritic diorite. The granodiorite reformed by late-stage strike-slip faulting tectonic event indicates that the strike-slip fault of Middle Kunlun and the collision of the Bayanhar block with East Kunlun were later than 246 Ma. Therefore, the formation of the QSG not only indicates the critical period of evolution of East Kunlun but also represents the tectonic transition from oceanic crust subduction to slab breaking.

关键词： East Kunlun Orogenic Belt(EKOB) Qushi’ang granodiorite(QSG) mafic microgranular enclaves(MME) Early Triassic Tibet Proto-Tethy

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Regional Tectonic Transformation in East Kunlun Orogenic Belt in Early Paleozoic: Constraints from the Geochronology and Geochemistry of Helegangnaren Alkali-feldspar Granite

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Acta Geologica Sinica(English Edition) 2013年第2期87卷 333-345页

作者： li ruibao PEI Xianzhi li Zhuochen SUN Yu PEI Lei CHEN Guochao CHEN Youxin liU Chengjun WEI Fanghui School of Earth Science and Resources Chang'an University Key Laboratory of Western China's Mineral Resources and Geological Engineering Ministry of Education National Key Laboratory of Remote Sensing Information and Image Analysis Technology Beijing Research Institute of Uranium Geology School of Earth Science and Resources China University of Geosciences

The Helegangnaren feldspar granite exposed in the eastern part of East Kunlun, is characterized by high concentrations of SiO2 and alkaline, low abundances of Fe, Mg and Ca, metaluminous-weak peraluminous. Trace elements analysis shows that the granite is depleted extremely in Ba, Sr and Eu, and rich in some large-ion lithophile elements and high field strength elements. Besides, the granite has high Ga contents, the values of 104（Ga/AI） vary from 2.50 to 2.77, which is mainly greater than the lower limit of A-type granites （2.6）, and is higher than the I- and S- type granites＇ average （2.1 and 2.28, respectively）. Rare earth element （REE） is characterized by relatively high fractionations of light REE （LREE） and heavy REE （HREE）（LREE/HREE=9.3-13.60, （La/Yb）N=10.92-18.02）, pronounced negative Eu anomalies （JEn=0.08-0.13）, and exhibits right- dipping gull pattern. Major elements, rare elements and trace elements features show the granite is ascribed to A-type granite and A2 subtype in tectonic genetic type. They are plotted into post-collision or within-plate area in a variety of tectonic discriminations. Geological and geochemical data comprehensively suggest that the granite is formed in a post-collision extensive tectonic setting. Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） zircon U-Pb dating yields a weighted mean age of 425 Ma, belonging to Middle Silurian, which is similar to the age of the post- collision geological events in the region. The differences of magmatic rocks in formation age, rocks assemblage and rocks series systematically indicate that the regional tectonic stress regime in the East Kunlun orogenic belt experienced a major transformation from compress to extension in Middle Silurianin, and the Helegangnaren feldspar granite intruded in the early stage of tectonic transformation.

关键词： A-type granite post orogeny compound orogeny East Kunlun

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Discovery of Early Paleozoic Garnet Amphibolite in the Wenquan Complex,Northern Margin of the Yili Block,NW China

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Acta Geologica Sinica(English Edition) 2021年第2期95卷 696-698页

作者： CHEN Youxin CHENG Kaikai PEI Xianzhi WANG Meng ZHAO Shaowei li Zuochen li ruibao PEI Lei GAO feng Key Laboratory of Western China's Mineral Resources and Geological Engineering Ministry of EducationSchool of Earth Science and ResourcesChang'an UniversityXi'an 710054China Mechanical Engineering Institute Xi'an Shiyou UniversityXi'an 710065China

Objective High-pressure(HP)and ultrahigh-pressure(UHP)minerals tend to be preserved in mafic and ultramafic metamorphic rocks(*** and garnet amphibolite)rather than felsic ***,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).

关键词： uplift depths thick

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U–Pb Zircon Geochronology and Geochemistry of the Neoproterozoic liujiaping Group Volcanics in the Northwest Margin of the Yangtze Block:Implications For the Breakup of the Rodinia Supercontinent

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Acta Geologica Sinica(English Edition) 2015年第4期89卷 1213-1225页

作者： li Zuochen PEI Xianzhi li ruibao PEI Lei liU Chengjun CHEN Youxin XU Tong YANG Jie WEI Bo Key Laboratory of Western China's Mineral Resources and Geological Engineering Ministry of EducationFaculty of Earth Science and ResourcesChang'an University Faculty of Earth Science and Mineral Resources China University of Geosciences

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.

关键词： geochemistry zircon LA-ICP-MS U-Pb age late Precambrian tectonics Shaanxiprovince

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