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| 1 | Magnetostratigraphy of the late Cenozoic Laojunmiao anticline in the northern Qilian Mountains and its implications for the northern Tibetan Plateau uplift显示文摘Cenozoic sediments in the foreland basin--Jiuquan Basin in west Hexi Corridor recorded tectonic uplift information of the Qilian Mountains. High resolution paleomagnetic dating of the Laojunmiao (LJM) section across the central LJM anticline in the southern Jiuquan Basin reveals ages of the Getanggou Member, Niugetao Member in the Shulehe Formation, the Yumen Conglomerate, Jiuquan Conglomerate and Gobi Formation at >13-8.3 Ma, 8.3-4.9 Ma, 3.66-0.93 Ma, 0.84-0.14 Ma and 0.14-0 Ma, respectively. Sedimentary evolution study suggests that the Qilian Mountains should begin to rise gradually since ~8-6.6 Ma, accompanied by sedimentary environments changing from lacustrine mudstones-sandstones to alluvial conglomerates. Rapid uplift of the Qilian Mountains began at ~3.66 Ma, followed by a series of stepwise or intermittent intensive uplifts at about <1.8-1.23 Ma, 0.93-0.84 Ma and 0.14 Ma, which finally resulted in the present high Qilian Mountains. | FANG Xiaomin1,2, ZHAO Zhijun3,2, LI Jijun2, YAN Maodu2, PAN Baotian2, SONG Chunhui2 & DAI Shuang2 1. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China 2. Key Laboratory of Western China’s Environmental Systems, Ministry of Education & College of Resources and Environment, Lanzhou University, Lanzhou 730000, China 3. College of Geography, Nanjing Normal University, Nanjing 210097, China | 2005 | Science China Earth Sciences2005,48,7: | 61 |
| 2 | Sr and O isotopic characteristics of porphyries in the Qinling molybdenum deposit belt and their implication to genetic mechanism and type显示文摘A great deal of Mesozoic hypobatholithic granites and hypabyssal porphyries develop in the Qinling Mountains. The former has long been regarded as transformation type (or S-type), and the latter associated with Mo-mineralization regarded as syntexis type (or l-type) granitoids. Statistics show that Sr, andδ18O of hypabyssal porphyries respectively range from 0.705 to 0.714, and from 7.2‰ to 12.1‰, agreeing with those of hypobatholithes (Sr1=0.705-0.710, δ18O = 6.1‰-10.4‰), which indicates that they share similar material sources and petrogenic mechanism. Based on analysis of lithological, mineralogical and geochemical characteristics of these granitoids and on study of their petrogenic tectonic background and regional geophysical data, we argue that both the shallow-seated porphyries and deep-seated batholithes were the products of Mesozoic collision between South China and North China paleocontinents. Subsequently, all these granti-toids should be attributed to collision type. | 陈衍景 李超 张静 李震 王海华 | 2000 | Science China Earth Sciences2000,43,S1: | 70 |
| 3 | 造山带中成对出现的高压麻粒岩与榴辉岩及其地球动力学意义显示文摘在一些典型碰撞造山带中,高压麻粒岩与榴辉岩在空间和时间上密切相关,它们之间的关系对揭示碰撞造山带的造山过程和造山机制具有重要意义。本文以中国西部的南阿尔金、柴北缘及中部的北秦岭造山带为例,详细陈述了这3个地区榴辉岩和相关的高压麻粒岩的野外关系、变质演化和形成时代,目的是要建立大陆碰撞造山带中榴辉岩和相关高压麻粒岩形成的地球动力学背景模式。南阿尔金榴辉岩呈近东西向分布在江尕勒萨依-玉石矿沟一带,与含夕线石副片麻岩、花岗质片麻岩和少量大理岩构成榴辉岩-片麻岩单元,榴辉岩中含有柯石英假象,其峰期变质条件为P=2.8~3.0GPa,T=730~850℃,并在抬升过程中经历了角闪岩-麻粒岩相的叠加;大量年代学研究显示其峰期变质时代为485~500Ma。南阿尔金高压麻粒岩分布在巴什瓦克地区,包括高压基性麻粒岩和高压长英质麻粒岩,它们与超基性岩构成了一个大约5km宽的构造岩石单元,与周围角闪岩相的片麻岩为韧性剪切带接触。长英质麻粒岩和基性麻粒岩的峰期组合均具有蓝晶石和三元长石(已变成条纹长石),形成的温压条件为T=930~1020℃,P=1.8~2.5GPa,并在退变质过程中经历了中压麻粒岩相变质作用叠加。锆石SHRIMP测定显示巴什瓦克高压麻粒岩的峰期变质时代为493~497Ma。都兰地区的榴辉岩分布柴北缘HP-UHP变质带的东端,在榴辉岩和围岩副片麻岩中均发现有柯石英保存,形成的峰期温压条件为T=670~730℃和,P=2.7~3.25GPa,退变质阶段经过了角闪岩相的叠加;榴辉岩相变质时代为420~450Ma。都兰地区的高压麻粒岩分布在阿尔茨托山西部,高压麻粒岩包括基性麻粒岩长英质麻粒岩,基性麻粒岩的峰期矿物组合为Crt+Cpx+Pl±Ky±Zo+Rt±Qtz,长英质麻粒岩的峰期矿物组合为:Grt+Kf+Ky+Pl+Qtz。峰期变质条件为T=800~925℃,P=1.4~1.85GPa,退变质阶段经历了角闪岩-绿片岩的改造,高压麻粒岩的变质时代为420~450Ma。北秦岭榴辉岩分布在官坡-双槐树一带,榴辉岩的峰期变质组合为Grt+Omp±Phe+Qtz+Rt,所计算的峰期温压条件为T=680~770℃和P=2.25~2.65GPa,年代学数据显示榴辉岩的变质时代为500Ma左右。北秦岭高压麻粒岩分布在含榴辉岩单元的南侧松树沟一带,包括高压基性麻粒岩和高压长英质麻粒岩,与超基性岩在空间上密切伴生,高压麻粒岩的峰期温压条件为T=850~925℃,P=1.45~1.80GPa,锆石U-Pb年代学研究显示其峰期变质时代为485~507Ma。以上三个实例显示,出现在同一造山带、在空间上伴生的高压麻粒岩和榴辉岩有各自不同的变质演化历史,但榴辉岩中的榴辉岩相变质时代和相邻的高压麻粒岩中的高压麻粒岩相变质作用时代相同或相近,这种成对出现的榴辉岩和高压麻粒岩代表了它们同时形成在造山带中不同的构造环境中,即榴辉岩的形成于大陆俯冲带中,而高压麻粒岩可能形成在俯冲带之上增厚的大陆地壳根部。 | 张建新 于胜尧 孟繁聪 李金平 | 2009 | 岩石学报2009,25,9: | 46 |
| 4 | The deformation pattern and fault rate in the Tianshan Mountains inferred from GPS observations显示文摘Based on GPS measurements conducted from 1992 to 2006, we present the current crustal movement velocity field for approximately 400 sites in the Tianshan Mountains and their adjacent areas, and estimate slip rates on the major faults using a 2-D elastic dislocation model. Our studies show slip rates within the range of 1―4 mm/a on the NW-SE trending strike-slip faults (such as Talas-Fergana fault) in the Tianshan Mountains. We also found the slip rates on the approximately WE-SN trending gently-dipping detachment fault vary from 10―13 mm/a for the southwest Tianshan Mountains to 2―5 mm/a for the eastern Tianshan Mountains, and to 6―12 mm/a for the Kyrgrz Tianshan. The GPS velocity field reveals that the total convergence is not uniformly distributed across the Tianshan Mountains, with 80%―90% of the N-S shortening absorbed along the southern and northern edges, and relatively little deformation accommodated within the interior. This first-order feature of strain pattern is explained best by underthrusting of adjacent blocks beneath the Tianshan Mountains along a basal detachment fault. We found the occurrence of historical M7―8 earthquakes somewhere in the locked ramp that connects the creeping and locking segments of the detachment, thereby resulting in elastic strain concentration and accumulation around it. The elastic strain confined in the upper crustal layer above the detachment ultimately releases through infrequent great earthquakes in the Tianshan Mountains, resulting in considerable folding and faulting at their margins. The Tianshan Mountains propagated outward and rose progressively as a wedge-shaped block. | YANG ShaoMin1,2, LI Jie1,3 & WANG Qi2,1 1 Research Center of Space Science and Technology, China University of Geosciences, Wuhan 430074, China 2 Institute of Seismology, China Earthquake Administration, Wuhan 430071, China 3 Earthquake Administration of Xinjiang Uygur Autonomous Region, Urumqi 830011, China | 2008 | Science China Earth Sciences2008,51,8: | 43 |
| 5 | The^(40)Ar/^(39)Ar age record of formation and uplift of the blueschists and eclogites in the western Tianshan Mountains显示文摘The 40Ar/39Ar ages indicate that the eclogite facies rocks of the Hasiate slice in the western Tianshan Mountains were formed at the early stage of Devonian (401 Ma) and had been uplifted to the greenschist facies tectonic level in the middle stage of Devonian (381 Ma). The formation and uplift of the blueschists of the Akesayi slice are constrained to the late stage of Devonian (370-364 Ma). The different tectonic slices in the high-pressure metamorphic belt have experienced the different uplift history. | GAO Jun, ZHANG Lifei & LIU Shengwei1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 2. Department of Geology, Peking University, Beijing 100871, Chin | 2000 | Chinese Science Bulletin2000,45,11: | 35 |
| 6 | The evidence of Sm-Nd isochron age for the early Paleozoic ophiolite in Mangya area,Altun Mountains显示文摘The REE patterns of the basic volcanic rocks in Mangya area, Altun, are slight rich in LREE with (La/Ya)-N=1.69-3.20, (La/Sm)-N=1.37-1.87, other trace element ratios of the rocks are Th/Ta≈1 (for a few samples greater than 1.5), Nb/Y=0.34-0.62, Ti/Y=310-443 (on the average: 381), Ti/V=37-62, Zr/Nb=9.4-12.4, Sr/Rb=12-80 (on the average: 37), and Nb/Th=7.7-16.8. These features are similar to that of E-MORE or OIB. The ε Nd(t) value, being 3.95- 4.12, shows that the source of the volcanic rocks is derived from depleted asthenosphere mantle mixed with materials from enriched mantle. These, together with the information of geological setting and rock assemblages, indicate that the basic volcanic rocks are of ophiolite. The Sm-Nd isotope ages for the eight basic volcanic rock samples construct a straight line with good correlation, and the calculated isochron age is (481.3±53) Ma. Besides, the eight calculated ε Nd(t) and model ages are close to each other, which suggests that they are homologous, so the isochron is not a mixed line. In the meantime, the isochron age ((481.3±53) Ma) is lower than the model ages (T DM=1 004-1 534 Ma) of the samples, suggeting that the isochron age represents the formation age of the basic volcanic rocks and the ophiolite belt in Mangya area, Altun is formed in the early Paleozoic (Cambrian-Ordovician). In spite of the greater uncertainty of the age, it is still reliable because it is consistent with the age constrained by the regional strata. | Liang Liu Zicheng Che Yan Wang Jinhai Luo Jianqi Wang Zhangjian Gao | 1998 | Chinese Science Bulletin1998,43,9: | 38 |
| 7 | Evidence for UHP metamor-phism of eclogites from the Altun Mountains显示文摘Ultrahigh pressure (UHP) metamorphism refers to metamorphism that has occurred at pressures for the stability of coesite. The polycrystalline quartz inclusions showing the characteristic texture within garnets of eclogites indicates the pre-existence of coesites under the peak meta-morphic condition. The unusual exsolution textures in om-pacites and apatites, and the pressure estimations of phengite-bearing eclogites have been taken to provide further proof of eclogite formation under the UHP conditions. Combined with the fact that coesites have been observed in country rocks of eclogites in North Qaidam Mountains, another UHP metamorphic belt cut by the large-scale strike-slip fault in the Altun-North Qaidam area of China is confirmed. | Jianxin Zhang Jingsui Yang Zhiqin Xu Fancong Meng Haibing Li Rendeng Shi | 2002 | Chinese Science Bulletin2002,47,9: | 33 |
| 8 | Recognition and implication of eclogite in the western Altun Mountains, Xinjiang显示文摘SINCE high-pressure metapelitic rocks have been discovered in the Beiketan area of eastern Al-tun Mountains,a set of eclogite has been recognized in south of Jianggesayi,western Altun.The eclogite,associated with quartz-garnet-clinopyroxenite and metamorphosed retrogradelyto garnet-amphibolite partially,is exposed in the Proterozoic meso- to hypometamorphic rocksand can be traced eastward to northwest of Mangya asbestos deposit,for about 200 | Liu, L Che, ZC Luo, JH Wang, Y Gao, ZJ | 1997 | Chinese Science Bulletin1997,42,11: | 33 |
| 9 | Fluidization model for continental collision in special reference to study ore-forming fluid of gold deposits in the eastern Qinling Mountains, China | 陈衍景 | 1998 | Progress in Natural Science:Materials International1998,8,4: | 31 |
| 10 | Precise timing of the Early Paleozoic metamorphism and thrust deformation in the Eastern Kunlun Orogen显示文摘In Dulan County, Qinghai Province NW China, the arc volcanic sequences in the northern side of the Central Fault of the East Kunlun were metamorphosed progressively from upper greenschist facies in the south to epidote-amphibolite facies in the north. High-angle thrust deformation was developed synchronously with the peak metamor-phim and superimposed with later low-angle striking-slip deformation. Zircon U-Pb dating yields a concordant age of (448±4) Ma for the metavolcanics. Syn-kinematic hornblende and muscovite separated from the high-angle thrusting belt give 40Ar-39Ar plateau age of (427±4) Ma and 408 Ma, respectively. These results precisely constrain the timing of the closure of early Paleozoic volcanic basin (Proto-Tethys) over the eastern portion of the East Kunlun Orogen, and the thrust tectonic slice had a cool rate of ca. 9°C/Ma. | CHEN Nengsong SUN Min HE Lei ZHANG Kexin WANG Guocan | 2002 | Chinese Science Bulletin2002,47,13: | 28 |
| 11 | Chronology of ultrahigh-pressure metamorphism in the Dabie Mountains and Su-Lu terrane: I. Sm-Nd isotope system显示文摘If the protolith of coesite-bearing eclogite was gabbro, it could undergo ultrahigh-pressure metamorphism under dry condition. In this case, the Hocking temperatures of those minerals could be higher, so that Nd isotope disequilibrium between minerals could be observed. If the protolith of coesite-bearing edogite was metabasalt, amphiboles in the metabasalt were decomposed during ultrahigh-pressure metamorphism and released water. Thus Nd isotope compositions between the minerals were in equilibrium because the blocking temperatures of those minerals could he lower. The secondary alteration and fluid-rock interaction in high-pressure are major problems for Sm-Nd dating of eclogite. The reliable Sm-Nd isotopic ages of coesite-bearing eclogite from the Dabie Mountains and Su-Lu terrane range from 221 to 232 Ma. They are slightly lower, but very close to the peak metamorphic ages of the eclogites. The cold eclogite from the Sujiahe complex could be oceanic subduction origin in the Paleozoic. | 李曙光 肖益林 葛宁洁 陈移之 Emil Jagoutz | 1996 | Science China Earth Sciences1996,39,6: | 27 |
| 12 | Climate changes in East China since the Late-glacial inferred from high-resolution mountain peat humification records显示文摘High-resolution peat humification records were obtained from Dajiuhu of the Shennongjia Mountains and Qianmutian of the Tianmu Mountains to study climate changes in East China.The analyses of pollen,organic matters,TOC,and Rb/Sr indicate a high degree of peat humification and thus strong decomposition of organic matter when climate was dry.Conversely,when climate was humid,the degree of humification is low because peat was preserved in a waterlogged condition.Peat humification from Dajiuhu occurred not only during the Younger Dryas(about 11.4-12.6 cal ka BP),the Blling-Allerd Warm Period(12.6-15.2 cal ka BP),and the Oldest Dryas(about 15.2-16.0 cal ka BP),but also during the early Holocene(about 11.4-9.4 cal ka BP),the 8.2 cal ka BP cold event,and the Holocene Optimum(about 7.0-4.2 cal ka BP).Both peat humification records since nearly 5 ka BP are consistent,showing that mountain peatland has synchronous responses to the East Asia monsoon-induced precipitation.The LOI data confirm the above observation.The monsoon precipitation since nearly 5 ka BP recorded in these two peat profiles can be divided into three phases.During 4.9-3.5 ka BP,precipitation amount was high but fluctuated greatly.During 3.5-0.9 ka BP,precipitation amount was low.During 0.9-0 ka BP,degree of humification reduced gradually,indicating the increase of monsoon precipitation.Contrast to other high-resolution records from East China monsoon region shows that the monsoon precipitation records of the two peat profiles since nearly 16 ka BP are controlled by a common forcing mechanism of summer solar radicalization in the Northern Hemisphere. | MA ChunMei ZHU Cheng ZHENG ChaoGui YIN Qian ZHAO ZhiPing | 2009 | Science China Earth Sciences2009,52,1: | 22 |
| 13 | ^(40)Ar/^(39)Ar Thermochronological Constraints on the Timing of Collisional Orogeny in the Mian-Lite Collision Belt,Southern Qinling Mountains显示文摘Silurian, Devonian and Carboniferous geological bodies in the Mianxian-Lueyang (Mian-Lue) collisional belt (MLB) and its neighbouring areas, southern Qinling Mountains, China, show similar characteristics of having undergone deformation of two stages. The earlier one, which is inferred to be related to collisional orogeny between the Yangtze and Sino-Korean palaeocontinents based on previous geological data, is responsible for large-scale, north-verging recumbent folds and overthrusts, and associated with low greenschist fades metamorphism. 40Ar/39Ar dating of three muscovite samples taken from different localities yields plateau ages of 226.9±0.9 and 219.5±1.4 Ma and an apparent age of 194.5±3.0 Ma. Thus, the late Triassic collision between the Yangtze and Sino-Korean palaeocontinents has been constrained. | LI Jinyi, WANG Zongqi and ZHAO Min Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037 | 1999 | Acta Geologica Sinica(English Edition)1999,73,2: | 23 |
| 14 | Interaction between subducted continental crust and the mantle --Ⅱ. Sr and Nd isotopic geochemistry of the syncollisional mafic-ultramafic intrusions in Dabie Mountains显示文摘The syncollisional mafic\|ultramafic rocks with Nb, Zr, Ti negative anomalies in the North Dabie terrane have Sr and Nd isotopic compositions with EMI features. Their low and variable initial ε Nd values ranging from -2 to -18 are similar to those of their gneissic country rocks and the ultrahigh\|pressure metamorphic rocks in the South Dabie terrane. These Sr and Nd isotopic features are difficult to be interpreted by mantle metasomatism related to oceanic subduction or crust assimilation, but is best explained by the mantle metasomatism related to continental subduction. | 李曙光 聂永红 S.R.Hart 张宗清 | 1998 | Science China Earth Sciences1998,41,6: | 19 |
| 15 | Age and genesis of the Shagou River terraces in eastern Qi-lian Mountains显示文摘The fluvial terrace sequence in eastern Qilian Mountains is a record of periodic uplift events of the Tibetan Plateau. Based on paleomagnetic dating, thermolumines-cence dating, radio carbon dating and loess-paleosol sequence on terraces, we preliminarily determine the ages of five major terraces of the Shagou River, northern side of the Qilian Mountains. The ages of five terraces were about 830, 418, 250,140 and 10 ka, respectively. Analysis on characteristics of terraces show that five major terraces were mainly tectonic genesis. Therefore, five major terraces recorded five strong rising events in the Qilian Mountains during the past 830 ka. The ages of those rising events are about the same as those terraces formation. Sub-terraces, constituting a main terrace, were perhaps mainly formed by climatic changes. | PAN Baotian WU Guangjian WANG Yixiang LIU Zhigang GUAN Qingyu | 2001 | Chinese Science Bulletin2001,46,6: | 18 |
| 16 | Effects of the Qinghai-Xizang (Tibetan) Plateau on the Circulation Features over the Plateau and Its Surrounding Areas显示文摘Areview of the effects of theTibetan Platean on circulation features over the plateau and its surrounding areas has been made, with a special emphasis upon the monsoon circulations in South Asin and East Asia. This includes estimates of heat sources, dynamic and thermal effects of the plateau, adn effects of the plateau on summer and winter monsoons. Major progresses made in this aspect by Chinese meteorologists have been specifically described and are compared with the achievements made by the meteorologists of other countries. | 丁一汇 | 1992 | Advances in Atmospheric Sciences1992,9,1: | 16 |
| 17 | Subduction of Continental Crust in the Early Palaeozoic North Qaidam Ultrahigh-Pressure Metamorphic Belt, NW China:Evidence from the Discovery of Coesite in the Belt显示文摘Coesite was discovered as inclusions in zircon separates from pelitic gneiss associated with a large eclogite body in the North Qaidam ultrahigh-pressure (UHP) terrane. Some graphite inclusions were also found. This finding suggested the occurrence of in-situ UHP metamorphism and that the terrane was most likely recrystallized at pressures below the diamond stability field. It supported other previous indirect UHP evidence, such as polycrystalline quartz inclusions in eclogitic garnet, quartz lamellae in omphacite and P-T estimates for both eclogite and garnet peridotite. The U-Pb and Sm-Nd ages of the North Qaidam eclogite indicated that subduction of continental crust occurred in the Early Palaeozoic, which probably recorded a collision between the Sino-Korean and Yangtze plates. | 杨经绥 许志琴 宋述光 张建新 吴才来 史仁灯 李海兵 Maurice BRUNEL Paul TAPPONNIER | 2002 | Acta Geologica Sinica(English Edition)2002,76,1: | 14 |
| 18 | Late Quaternary normal faulting and its kinematic mechanism of eastern piedmont fault of the Haba-Yulong Snow Mountains in northwestern Yunnan, China显示文摘The regional geologic and geomorphic observations show that an active arcuate normal fault constitutes the main boundary fault of the Haba-Yulong Snow Mountains (HYSM). This fault is called eastern piedmont fault of Haba-Yulong Snow Mountains (HYPF). The fault consists of two segments with differential trend; the northern segment is NW-trending and NE-dipping and the southern section is S-N trending and E-dipping. Three sets of fault scarps cutting late Quaternary landforms and their dating results indicate that the fault is a prominent Holocene active fault and its throw rates are 0.3―1.4 mm/a during late Quaternary. The geometry and kinematics of the fault suggest that the arcuate normal faulting or rifting are typical surface deformation pattern at the two tips of the Z-shaped rift zone of northwestern Yunnan, which is related to regional east-west extension accompanying clockwise rota- tion of micro-block. | WU ZhongHai ZHANG YongShuang HU DaoGong ZHAO XiTao YE PeiSheng | 2009 | Science China Earth Sciences2009,52,10: | 14 |
| 19 | Geological characteristics and evolution of the Kunlun Mountains region during the early Paleozoic显示文摘In the West Kunlun Mountains there exists a Caledonian tectonic zone. The fifth suture zone of the Qinghai-Xizang Plateau was formed as a result of closing of the proto-Tethys Sea caused by the Caledonian movement. The discovery of the Sinian- Cambrian Wanbaogou Group and the Middle Ordovician-Silurian Halagel Group around the Golmud area in East Kunlun, the discovery of the early Paleozoic rockbodies at Wanbaogou and Huxiaoqing, and the unconformity between the Devonian molasse and the underlying strata provide evidence for the existence of the Caledonian tectonic zone. There are not only similarities, but also significant differences between the East Kunlun and West Kunlun. | 潘裕生 周伟明 许荣华 王东安 张玉泉 谢应雯 陈挺恩 罗辉 | 1996 | Science China Earth Sciences1996,39,4: | 13 |
| 20 | Geochronological evidence of Indosinian(high-pressure) metamorphic event and its tectonic significance in Taxkorgan area of the Western Kunlun Mountains,NW China显示文摘The CL images,LA-ICP-MS in situ trace elements analysis,and U-Pb dating for zircons indicate that the metamorphic ages of the sillimanite-garnet-biotite gneiss and the garnet-amphibole gneiss from eastern Taxkorgan of the Western Kunlun Mountains are 220±2 and 220±3 Ma respectively,and their protolith ages are younger than 253±2 and 480±8 Ma respectively.Two samples were collected at the same outcrops with HP mafic granulite and HP pelitic granulite.Mineral assemblage of the sillimanite-garnet-biotite gneiss(Grt+Sill+Per+Q) is consistent with that of HP pelitic granulite at early high amphibolite-granulite facies stage.Mineral assemblage of the garnet-amphibole gneiss(Grt+Amp+Pl+Q) is consistent with retro-metamorphic assemblage of HP mafic granulite at amphibolite facies stage.The dating results suggest that these HP granulites underwent peak metamorphism at 220±2 to 253±2 Ma.Thus,the Kangxiwar tectonic zone was probably formed by subduction and collision of the Paleo-Tethys Ocean during Indosinian.Protolith ages of the two samples,together with previously published U-Pb zircon dating age,suggest that the sillimanite-garnet schist-quartzite unit is a late Paleozoic unit,not a part of the Paleoproterozoic Bulunkuole Group. | YANG WenQiang1,LIU Liang1,CAO YuTing1,WANG Chao1,2,HE ShiPing2,LI RongShe2 & ZHU XiaoHui1 1 State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China 2 Xi’an Institute of Geology and Mineral Resource,Xi’an 710054,China | 2010 | Science China Earth Sciences2010,53,10: | 13 |