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An alternative tectonic model for the Yarlung zangbo suture zone

Science China Earth Sciences 2010年第1期53卷 27-41页

作者： LIU XiaoHan JU YiTai WEI LiJie LI GuangWei Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100085China Mineral Resource Institute of China Metallurgical Geology Bureau Beijing 100025China

The new field investigations along the Yarlung zangbo ophiolites zone show that these series underwent low green-schist metamorphism and were then fractured and occurred as slabs in tectonic melanges,without regional tectonic *** large shear zone in north-south direction has been identified between ophiolite bodies and flysch layers on both side and a conformable contact relationship can be observed locally between them.A great mass of tectonic mélange has been substantiated as submarine olistolith *** Mesozoic sedimentary facies and its evolution in both north and south of the ophiolite zone are corresponding in *** ophiolite zone has often been divided into parallel branches,separated by narrow flysch *** is also a similarity of the Paleozoic and the basement of the High Himalaya,Lhasa and Qiangtang Terranes,and they are distinctly different from those of the Indian *** geologic information does not warrant a postulate that the Himalaya and Tibet were once separated by a great ocean;it is therefore consistent with an alternative tectonic model by back-arc basin collapse with its juvenile narrow oceanic *** real plate tectonic suture,the Neotethys might be covered under the Miocene Siwalik molasse in the southern slope of the High Himalaya *** on the new model,the Neotethyan ocean floor was subducted beneath the Asia since the Late *** outer continental margin of Eurasia was split from the Lhasa Terrane so that a back-arc basin came into ***-pelagic and deep sea sediments were deposited before the Late Cretaceous flysch sedimentation,with the linear juvenile oceanic crust when back-arc volcanism occurred in the Gandese *** Yarlung zangbo back-arc basin was eventually eliminated when the High Himalayas were sutured onto *** ocean floor lightly underthrusted to north and south sides,sediments of the basin were deformed as *** Neotethys was eliminated during the Terti

关键词： Yarlung zangbo Ophiolite Zone plate boundary continental marginal arc relic back-arc basin alternative tectonic model

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Mineralogy and Geochemistry of the High-Cr Podiform Chromitite from the Cuobuzha Ophiolite, Yarlung zangbo Suture Zone, Western Tibet, China: Implication for its Origin

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Acta Geologica Sinica(English Edition) 2020年第1期94卷 75-89页

作者： ZHAO Hui YANG Jingsui LIU Fei XIONG Fahui LIAN Dongyang YAO Hu Harbin Institute of Technology Harbin 150001China Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen 518055China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China School of Earth Sciences and Engineering Nanjing UniversityNanjing 201123China Institute of Geochemistry Chinese Academy of Sciences Guiyang 550081China

The Cuobuzha high-Cr chromitites in the western segment of Yarlung zangbo Suture Zone of Tibet are mainly hosted in the harzburgites as massive type, which are characterized by high concentrations of platinum group elements(PGE) ranging from 380 to 577 ppb, and low Pd/Ir ratios(<0.1). In mid-ocean ridge basalts(MORB)-normalized spidergrams, chromites of the Cuobuzha chromitites are depleted in Al, Ga, V, Mg and Zn, and enriched in Mn and Cr, sharing similar patterns with those of ophiolitic boninites in the Bonin and Thetford Mines. Approximately 20 platinum group mineral(PGM) grains were discovered from the samples, including laurite, erlichmanite, Os-Fe alloy, cuproiridsite, and irarsite. The PGM assemblages indicate that sulfur fugacity was initially low enough to allow the precipitation of Os-Fe alloy and increased thereafter, with the fall in temperature. Primary Fe-Ni and Fe-Cr alloys, which are stable in a highly reduced environment, occur as inclusions within chromites or clinopyroxenes. Calculated results show that the parental magma has an intimate affinity with boninites. Based on our observations, a model is proposed wherein the Cuobuzha chromitites contain high-pressure and low-pressure chromites. Low-pressure chromites were formed via reaction between boninitic melts and peridotites, during which the high-pressure chromites hosting highly reduced minerals were mobilized by melts and were reallocated to podiform chromitites.

关键词： Cuobuzha chromitites highly reduced minerals Yarlung zangbo Suture Zone Tibet

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Middle Jurassic-early Cretaceous radiolarian assemblages of the western Yarlung zangbo Suture Zone: Implications for the evolution of the Neo-Tethys

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Geoscience Frontiers 2017年第5期8卷 989-997页

作者： Hanting Zhong Jingen Dai Chengshan Wang Yalin Li Yushuai Wei State Key Laboratory of Biogeology and Environmental Geology School of Earth Sciences and Resources Research Center for Tibetan Plateau Geology China University of Geosciences (Beijing) Beijing 100083 China Institute of Sedimentary Geology Chengdu University of Technology Chengdu 610059 China

Cherts in the Zhongba melange of the western Yarlung zangbo Suture Zone(YZSZ) contain well preserved radiolarian assemblages. These radiolarian assemblages indicate that the Zhongba melange has middle Jurassic-early Cretaceous remnant, are coeval with those from the central and eastern parts of the YZSZ. Cherts from the Najiu area yield Aalenian to Aptian radiolarians, while cherts interbedded with siliceous mudstones from the Bielongjiala area yield Aptian radiolarians, indicating that terrigenousderived sediments were deposited during early Aptian. The above observations indicate that the entire YZSZ have a similar geochronological framework and thus they underwent similar geological evolution:(1) during the Jurassic, the Neo-Tethys was a wide ocean with pelagic sediments distal from continents;(2) during the Cretaceous(around 130-120 Ma), the Neo-Tethys started to subduct along the southern margin of the Lhasa block, and terrigenous-derived siliceous mudstone began deposition.

关键词： Radiolarian chert Jurassic Cretaceous Yarlung zangbo Suture Zone

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Mesozoic radiolarian chert from the middle sector of the Yarlung zangbo suture zone,Tibet and its tectonic implications

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Science China Earth Sciences 2006年第4期49卷 348-357页

作者： ZHU Jie1,2, DU Yuansheng1, LIU Zaoxue2, FENG Qinglai1, TIAN Wangxue2, LI Jinping2 & WANG Changping2 1. Faculty of Earth Sciences,China University of Geology, Wuhan 430074, China 2. Hubei Institute of Regional Geology Survey, Wuhan 430034, China 1. Faculty of Earth Sciences China University of Geology Wuhan 430074 China 2. Hubei Institute of Regional Geology Survey Wuhan 430034 China

Three radiolarian fauna, aged as the Middle-Late Triassic, Late Jurassic-Early Creta- ceous and Cretaceous radiolarian fauna, have been recognised in the radiolarian cherts from the middle sector of the Yarlung zangbo suture zone, southern Tibet, China. The average contents of SiO2 in the radiolarian cherts of the Middle-Late Triassic and Late Jurassic-Early Cretaceous are 90.24% and 92.58% respectively, with average ratios of Al/(Al+Fe+Mn) as 0.75 and 0.74 respectively, the average ratios of MnO/TiO2 as 0.36 and 1.24, the average ratios of Ce/Ce* as 1.15 and 1.03, and the average ratios of LaN/CeN as 0.85 and 0.93. These geochemical features indicate that both of them are biogenic, deposited in a continental margin basin. The SiO2 content of the Early Cretaceous radiolarian chert is 94.12%, with the ratio of Al/(Al+Fe+Mn) as 0.59, ratio of MnO/TiO2 as 4.30, ratio of Ce/Ce* as 0.60, ratio of LaN/CeN as 1.59, which imply that the chert is biogenic and was deposited in a pelagic basin. The Middle-Late Triassic association of the radiolarian chert and turbidites as well as their geochemical characteristics indicates the existence of a strong rifting marginal basin in the belt of the Yarlung zangbo River then. The association of radiolarian chert and bedded basalt indicate an initial Tethyan ocean basin in southern Tibet during the Late Jurassic-Early Cretaceous. The early Cretaceous radiolarian chert coexisting with pillow basalt in top of the ophiolite suite represents sediments from the oceanic Tethyan basin.

关键词： radiolarian chert, sedimentary geochemistry, Mesozoic, Yarlung zangbo suture zone, Tibet.

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Helium and neon isotopic compositions in the ophiolites from the Yarlung zangbo River,Southwestern China:The information from deep mantle

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Science China Earth Sciences 2007年第6期50卷 801-812页

作者： YE XianRen TAO MingXin YU ChuanAo ZHANG MingJie Institute of Geology and Geophysics Chinese Academy of SciencesLanzhou 730000China Department of Geology Lanzhou UniversityLanzhou 730000China

The ophiolites from the Yarlung zangbo River (Tibet), Southwestern China, were analysed for the contents of helium and neon and their isotopic compositions by stepwise heating. The serpentinites from Bainang showed a high 3He/4He value of 32.66R a (R a is referred to the 3He/4He ratio in the present air) in 700°C fraction. At lower temperature, all of the dolerites displayed as very high 3He/4He ratios as ones investigated for hotspots. It was clear that the high 3He/4He ratio was one of immanent characterics in the magma source formed the dolerites, suggesting that there was a large amount of deep mantle fluids in these rocks. In the three-isotope diagram of neon, the data points from the ophiolites of the Yarlung zangbo River were arranged along the Loihi Line. This is in agreement with the characteristics of helium isotopes, revealing that the high-3He plume from deep mantle had played an important role in the formation of the Neo-Tethyan Ocean. The helium isotopic compositions in the basalts were far higher than atomospheric value but lower than the average value of MORB, although there were various degrees of alteration. The possible reasons were that basaltic magmas had been contaminated by crust-derived fluids.

关键词： Yarlung zangbo River (Tibet) ophiolite helium neon isotope plume

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Formation mechanism and development pattern of aeolian sand landform in Yarlung zangbo River valley

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Science China Earth Sciences 1999年第3期42卷 272-284页

作者：李森董光荣申建友杨萍刘贤万王跃靳鹤龄王强 1. Institute of Desert Research Chinese Academy of Sciences 730000 Lanzhou China 2. Xi’an State Key Laboratory of Loess and Quatemaq Geology Chinese Academy of Sciences 710054 Xi’an China 3. Lanzhou Meteorological Center 730000 Lanehou China

Aeolian sand landforms in the Yarlung zangbo River valley can be divided into 4 classes and 21 types. The river valley has favourable environment conditions for the development of aeolian sand landforms. Simulation of MM4 mid-scale climate model showed that the near-surface flow field and wind vector field during the winter half year in the river valley are generally favourable for the aeolian sand deposition and as a whole they also affect the distribution mneu and sites of aeolian sand landforms. Sand dunes and sand dune grouup in the river valley developed mainly in three ways, namely windward retarding deposition, leeward back flow deposition and bend circumfluence deposition. Through alternating positive-reverse processes of sand dune formation under wind actions and sand dune vanishing under water actions, sand dunes developed fmm primary zone thmugh main-body zone then to vanishing zone where climbing dunes and falling dunes are declining and are even disappearing.

关键词： Yarlung zangbo River valley aeolian sand landform near-surface flow field positive-reverse development processes evolutional pattern.

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Apatite fission track dating evidence for tectonic movement of Yarlung zangbo Thrust Zone

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Chinese Science Bulletin 2002年第9期47卷 765-768页

作者： YUAN Wanming HOU Zengqian WANG Shicheng LI Shengrong Institute of High Energy Physics.Chinese Academy of Sciences Beijing 100080China Institute of Mineral Resources Chinese Academy of Geological SciencesBeijing 100037China China University of Geosciences Beijing 100083China

Fission track geological chronology is an effective method of study on tectonic movement of fault zone. Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi, -70-km-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from-37 to 14 Ma, indicating the time of major tectono-thermal events, i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: -37-20 Ma and 20-14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was -1020 m and total -2.9 km of overburden has been removed from the present-day surface since cooling below -110°C began. The maximum cooling and denudation

关键词： fission track dating thrusting thermal event uplifting Yarlung zangbo Zone Tibet.

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STUDY ON THE MOISTURE PASSAGE ON THE LOWER REACHES OF THE YARLUNG zangbo RIVER

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Science China Chemistry 1989年第5期32卷 580-593页

作者：杨逸畴高登义李渤生 Institute of Geography Academia Sinica Beijing Institute of Atmospheric Physics Academia Sinica Beijing Institute of Botany Academia Sinica Beijng

A series of gorges on the lower reaches of the Yarlung zangbo River is like an enormous crevice splitting the southeastern Qinghai-Xizang (Tibet)Plateau to create a passage through which warm, wet air flow from the Indian Ocean reaches the inner part of the plateau. This moisture passage was mainly strengthened after the Pleistocene epoch in the Quaternary period and has played a major role in affecting the beginning date of the rainy season and the amount of the plateau’s rainfall. It has also served as a corridor for the living things on the southern and the northern sides of the Himalayas to mingle with each other. The region along this passage is abundant in evidences of species of differentiation, variation and biological division. Also the passage has provided a favorable environment for human beings and affected natural phenomena there.

关键词： moisture passage the Great Bend Gorge of the Yarlung zangbo River the tectenic movement of the Qinghai-Xizang crust.

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THE　CAUSES　AND　DEVELOPMENTAL　TREND　OF　DESERTIFICATION　IN　THE　MIDDLE　REACHES　OF　THE　YARLUNG　zangbo　RIVER　AND　ITS　TWO　TRIBUTARIES　IN　XIZANG

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Chinese Geographical Science 1995年第4期5卷 355-364页

作者：董光荣董玉祥李森金炯靳鹤龄刘玉璋 Institute of Desert Research the Chinese Academy of Sciences Lanzhou PRC

The middle reaches of the Yarlung zangbo River and its two tributaries are an important development and construction region in Xizang(Tibet) in recent years, but the fast development of desertification has caused immense damages to its social and economic development, so the study on desertification in this region is significant. The paper studies the causes and development trend of desertification in this region through analysis of natural and human factors as well as their relationship. It can be concluded that desertification in the study area is one process which is accelerated and intensified by human activities on the basis of the slow natural desertification process. It is resulted from the dislocation of irrational and intensive human activities, fragile eec-environment and meagre natural resources, and tends to become more wide and severe.

关键词： desertification eco-environment the Yarlung zangbo River Xizang

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Study on thermal infrared remote sensing of Yarlung zangbo River and Bangong Co-Nujiang River suture belt in Qinghai-Tibet Plateau

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Science China(Technological Sciences) 2006年第Z2期49卷 108-113页

作者： BI Siwen, YAN Hao & WANG Changyao State Key Laboratory of Remote Sensing Sciences, Institute of Remote Sensing Application, Chinese Academy of Sciences, Beijing 100101, China Key Laboratory of Three-Dimensional Information Acquisition and Application, Ministry of Education, Capital Normal University, Beijing 100037, China Chinese Acad Sci Inst Remote Sensing Applicat State Key Lab Remote Sensing Sci Beijing 100101 Peoples R China Capital Normal Univ Minist Educ Key Lab Dimens Informat Acquisit & Applicat Beijing 100037 Peoples R China

The area change of heat abnormity is not in accordance with conclusions of former thermal infrared remote sensing studies of the Qinghai-Tibet Plateau, which were that the temperature of Yarlung zangbo River suture belt of the southern Plateau is high and the northern temperature is low. The study result in this paper shows that the highest temperature is found in the Bangong Co-Nujiang River suture belt, the Yarlung zangbo River suture belt temperature is the second highest, and the northern Tibet temperature is the lowest. The study demonstration area was the suture belt areas of the Yarlung zangbo River and the Bangong Co-Nujiang River in the Qinghai-Tibet Plateau, where the land temperature of the Qinghai-Tibet Plateau and the bore temperature of field land surface were measured and the emissivity of land surface was calculated. In addition, the authors explore the mechanism of the relationship between thermal infrared remote sensing and constructing thermodynamics and reach four new conclusions about the thermodynamics of the Tibet Plateau.

关键词： Qinghai-Tibet Plateau, Yarlung zangbo River-Bangong Co-Nujiang River, suture belt, thermal infrared remote sensing, heat abnormity.

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