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1Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics显示文摘Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and regional seismograph network of China, and employed 'Cut and Paste' method to obtain focal mechanisms and depths of the big aftershocks (M≥5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY) are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (~18 km). So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault. The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.ZHENG Yong1,2,MA HongSheng3,Lü Jian4,NI SiDao5,LI YingChun6 & WEI ShengJi2 1 Institute of Geodesy and Geophysics,Chinese Academy of Sciences,Wuhan 430077,China 2 Institute of Geophysics,Chinese Earthquake Administration,Beijing 100086,China 3 Institute of Earthquake Science,Chinese Earthquake Administration,Beijing 100086,China 4 Earthquake Administration of Jiangxi Province,Nanchang 330039,China 5 School of Earth and Space Science,University of Science and Technology of China,Hefei 230026,China 6 Earthquake Administration of Jiangsu Province,Nanjing 210014,China 2009Science China Earth Sciences2009,52,6:100
2SHRIMP dating of the Bangong Lake SSZ-type ophiolite: Constraints on the closure time of ocean in the Bangong Lake-Nujiang River,northwestern Tibet显示文摘The Bangong Lake ophiolite is located in the westernmost part of the Bangong Lake-Nujiang River suture zone. It is a tectonic mélange consisting of numerous individual blocks of peridotite, pillowed and massive lavas and mafic dykes with SSZ-type ophiolitic geochemical affinity formed at the end of a Wilson circle. The SHRIMP U-Pb ages of the co-magmatic zircon domains from one gabbroic dyke (Sample 01Y-155) range from 162.5±8.6 Ma to 177.1±1.4 Ma with an average of 167.0±1.4 Ma (n = 12, MSWD = 1.2), suggesting that the subduction of the Bangong Lake Neo-Tethyan Ocean started before the Middle Jurassic. It is inferred that the tectonic transform from spreading to subduction of the Neo-Tethyan Ocean began before the Middle Jurassic in the Bangong Lake area.SHI RenDeng1,2 1 School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 2 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China (email: shird@ustc.edu.cn) 2007Chinese Science Bulletin2007,52,7:70
3Neoproterozoic magmatic activity and global change显示文摘Neoproterozoic is a very important time in the history of the Earth, during which occurred supercontinent breakup, low-latitude glaciation, and biotic diversification. These concern a series of interdisciplinary studies involving ancient plate motion, climate change and life evolution, re-sulting in many forefront topics of general interest in the earth sciences. These include exact ages bracketing the Cryogenian System and glaciations, initial age and lasted duration of supercontinent breakup, dynamic reconstruction of China continents in supercontinental configurations, the nature of rift magmatism and extent of hydrothermal altera-tion, paleoclimatic implication of water-rock interaction and low-18O magmatism, and relationship between superconti-nental evolution and global change. A number of outstanding advances in the above aspects have being made by Chinese scientists, leaving many important issues to be resolved: (1) did the Cryogenian start at either 800 to 820 Ma or 760 to 780 Ma? (2) was South China in the supercontinental con-figuration located in either southeast to Australia or north to India? (3) are Paleoproterozoic to Archean ages of crustal rocks a valid parameter in distinguishing North China from South China? Available observations suggest that Neopro-terozoic mantle superwelling occurred as conspicuous mag-matism in South China but as cryptical magmatism in North China. Mid-Neoproterozoic mantle superplume event and its derived rift-magmatism would not only result in the supercontinental demise, but also play a very important role in the generation and evolution of the snowball Earth event by initiating the global glaciation, causing the local degla-ciation and terminating the snowball Earth event.ZHENG Yongfei School of Earth and Space Sciences, University of Science and Technol-ogy of China, Hefei 230026, China (e-mail: yfzheng@ustc.edu.cn) 2003Chinese Science Bulletin2003,48,16:58
4Mantle xenoliths from Late Cretaceous basalt in eastern Shandong Province: New constraint on the timing of lithospheric thinning in eastern China显示文摘The age of the alkali basalt from Daxizhuang in Jiaozhou, eastern Shandong, was determined to be 73.5±0.3 Ma by 40Ar-39Ar technique. The basalt gave high eNd(t) values of +7.5 and +7.6, suggesting that the primitive magma was derived from depleted asthenospheric mantle with a formation depth of about 65—95 km. Spinel-lherzolite xenoliths have been discovered in the basalt. The Fo values of olivine from the xenoliths range from 88 to 89. The estimated equilibrium P-T conditions of spinel-lherzolite xenoliths are about 2.0 GPa and 1010—1140℃, suggesting an equilibrium depth of about 65 km. Geochemical characteristics of the Late Mesozoic (125—115 Ma) mantle-derived rocks in Shandong Province suggest an enriched lithospheric mantle along the southern margin of the North China block. However, geochemical characteristics of the Late Cretaceous basalts in Daxizhuang and the equilibrium P-T condition estimated from the xenoliths suggest that the lithosphere at 73 Ma ago was as thick as that of the Cenozoic in the region. Additionally, the xenoliths are rich in basaltic-component, suggesting a derivation from a newly-formed lithosphere. Therefor, lithospheric thinning took place at a time interval between about 120 and 73 Ma along the southern margin of the North China block.YAN Jun, CHEN Jiangfeng, XIE Zhi & ZHOU Taixi School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 2003Chinese Science Bulletin2003,48,19:59
5The 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 2008Science China Earth Sciences2008,51,8:43
6A numerical study of the South China Sea deep circulation and its relation to the Luzon Strait transport显示文摘A fine-resolution MOM code is used to study the South China Sea basin-scale circulation and its relation to the mass transport through the Luzon Strait. The modal domain includes the South China Sea, part of the East China Sea, and part of the Philippine Sea so that the currents in the vicinity of the Luzon Strait are free to evolve. In addition, all channels between the South China ,Sea and the Indonesian seas are closed so that the focus is on the Luzon Strait transport. The model is driven by specified Philippine Sea currents and by surface heat and salt flux conditions. For simplicity, no windstress is applied at the surface.The simulated Luzon Strait transport and the South China Sea circulation feature a sandwich vertical structure from the surface to the bottom. The Philippine Sea water is simulated to enter the South China Sea at the surface and in the deep ocean and is carried to the southern basin by western boundary currents. At the intermediate depth, the net Luzon Strait transport is out of the South China Sea and is fed by a western boundary current flowing to the north at the base of the thermocline. Corresponding to the western boundary currents, the basin circulation of the South China Sea is cyclonic gyres at the surface and in the abyss but an anti-cyclonic gyre at the intermediate depth. The vorticity balance of the gyre circulation is between the vortex stretching and the meridional change of the planetary vorticity.Based on these facts, it is hypothesized that the Luzon Strait transports are determined by the diapycnal mixing inside the entire South China Sea. The South China Sea plays the role of a 'mixing mill' that mixes the surface and deep waters to return them to the Luzon Strait at the intermediate depth. The gyre structures are consistent with the Stommel and Arons theory (1960), which suggests that the mixlng-induced circulation inside the South China Sea should be cyclonic gyres at the surface and at the bottom but an anti-cyclonic gyre at the intermediate depth. The simulated gyre circulation at the intermediate depth has been confirmed by the dynamic height calculation based on the Levitns hydrography data.The sandwich transports in the Luzon Strait are consistent with recent hydrographic, al observations.Model results suggest that the Kuroshio tends to form a loop current in the northeastern South China Sea. The simulated Kuroshio Loop Current is generated by the pressure head at the Pacific side of the Luzon Strait and is enhanced by theβ- plane effects. The β- plane appears to be of paramount importance to the South China Sea circulation and to the Luzon Strait translports. Without theβ-plane, the Luzon Strait transports would be greatly reduced and the South China Sea circulation would be complete-ly different.Yuan Dongliang1. Goddard Earth Science and Technology Center, University of Maryland, Baltimore County Code 971, Laboratory for Hydrospheric Processes, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA 2002Acta Oceanologica Sinica2002,21,2:37
7Decoupling of surface and subsurface sutures in the Dabie orogen and a continent-collisional lithospheric-wedging model: Sr-Nd-Pb isotopic evidences of Mesozoic igneous rocks in eastern China显示文摘There are significant differences of Nd and Pbisotopic compositions between Mesozoic mafic igneous rocks from the North China Block (NCB) and the South ChinaBlock (SCB). Mesozoic mantle-derived igneous rocks fromthe North China Block have very low e Nd values (-15 to -21), and 206Pb/204Pb ratios (< 17.9), while those in the SCB are characterized by e Nd > -10 and 206Pb/204Pb > 18.3. The verylow e Nd values (-16 to -20) and 206Pb/204Pb ratios (< 17.3) of the early Cretaceous mafic-ultramafic intrusions developedin the north part of the Dabie orogen (NDZ) suggest that the deep lithosphere underneath the NDZ belongs to the NCBbut not the SCB. Therefore, although the surface suture be-tween the NCB and SCB is located on the north side of theNDZ, the subsurface suture between the NCB and SCBshould be located to the south side of the NDZ. This is con-sistent with the previous suggestion that the subsurface su-ture in the Sulu terrane east of the Tanlu fault was the south displacement, but contradictory to northward continentalsubduction of the SCB. A continent-collisional lithospheric-wedging model can interpret the decoupling of the surface and subsurface sutures in the Dabie-Sulu orogen. After slabbreak-off, the continuing convergence of two continental blocks must increase the compression force acting on the suture zone, which might induce the lithosphere splitting of SCB. Thus, the lower crust and lithospheric mantle on thesouth margin of the NCB can wedge into the north margin of the lithosphere of the SCB along the Dabie-Sulu collisionzone. This process caused the overthrust of the mid-upper continental crust with exhumed ultrahigh pressure meta-morphic (UHPM) rocks and underthrust of the deep litho-sphere of the SCB. It could be an important mechanism re-sponsible for the second rapid cooling and uplifting of theUHPM rocks and lithospheric delamination as well as thecorresponding magmatism in Jurassic in the Dabie orogen.The southward movement of subsurface suture in theDabie-Sulu orogen may also provide a tectonic setting indepth for the large-scale Mesozoic magmatic-metallogenesis along the middle-lower reaches of the Yangtse River in east-ern China.LI Shuguang & YANG Wei School of Earth and Space Sciences, University of Science and Tech-nology of China, Hefei 230026, China 2003Chinese Science Bulletin2003,48,8:37
8An Archean continental block in the Taihangshan and Hengshan regions: Constraints from geochronology and geochemistry显示文摘Recent research on the tectonothermal evolution and geochronology in the Fuping, Hengshan and Wutaishan metamorphic complexes, together with the discoveries of a high-pressure granulite belt in the northern margin of the North China Craton (NCC) and high-pressure metapelites in the Jingangku Group of the Wutaishan complex, suggests that there was a Neoarchean to Paleoproterozoic orogenic belt related to collision between the Eastern and Western continental blocks. Comparison of geological, geochronological, tectonothermal and geochemical data between the Fuping and Hengshan complexes suggests these two complexes most likely originated and evolved as a single lithotectonic domain (i.e., the Taihangshan-Hengshan block) during the early evolution of the North China Craton, probably as an active margin to the Eastern Continental Block. The Taihangshan-Hengshan block has been subjected to intensive and extensive tectono-magmatism and high-grade metamorphism related to collision between the Eastern and Western continental blocks at ~1.80 Ga.LIU Shuwen , LI Jianghai, PAN Yuanming, ZHANG Jian and LI Qiugen(1. The Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China 2. Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada) 2002Progress in Natural Science:Materials International2002,12,8:32
9New development thoughts on the bio-inspired intelligence based control for unmanned combat aerial vehicle显示文摘Bio-inspired intelligence is in the spotlight in the field of international artificial intelligence,and unmanned combat aerial vehicle(UCAV),owing to its potential to perform dangerous,repetitive tasks in remote and hazardous,is very promising for the technological leadership of the nation and essential for improving the security of society.On the basis of introduction of bioinspired intelligence and UCAV,a series of new development thoughts on UCAV control are proposed,including artificial brain based high-level autonomous control for UCAV,swarm intelligence based cooperative control for multiple UCAVs,hy-brid swarm intelligence and Bayesian network based situation assessment under complicated combating environments, bio-inspired hardware based high-level autonomous control for UCAV,and meta-heuristic intelligence based heterogeneous cooperative control for multiple UCAVs and unmanned combat ground vehicles(UCGVs).The exact realization of the proposed new development thoughts can enhance the effectiveness of combat,while provide a series of novel breakthroughs for the intelligence,integration and advancement of future UCAV systems.DUAN HaiBin 1 ,SHAO Shan 2 ,SU BingWei 3 &ZHANG Lei 41 State Key Laboratory of Science and Technology on Holistic Flight Control,School of Automation Science and Electrical Engineering, Beijing University of Aeronautics and Astronautics,Beijing 100191,China 2 Flight Control Department,Shenyang Aircraft Design and Research Institute,Shenyang 110035,China 3 Beijing Institute of Near Space Vehicle’s System Engineering,Beijing 100076,China 4Integration and Project Section,Air Force Equipment Academy,Beijing 100085,China 2010Science China(Technological Sciences)2010,53,8:32
10Seasonal water storage change of the Yangtze River basin detected by GRACE显示文摘US-Germany co-sponsered satellite gravimetry mission GRACE (Gravity Recovery And Climate Experiment), launched in March 2002, has been producing monthly time series of Earth gravity models up to degree and order of 120. The GRACE mission consists of two identical satellites flying on an almost polar orbit with an altitude of about 300-500 km and satelite-to-satellite ranging of about 220 km. Thanks to the payloads of space-borne GPS receivers, accelerometers and high-precision K-band satelite-to-satellite ranging mesurements, GRACE gravity models are expected to achieve more than one order of magnitude of improvement over previous models at spatial scales of a few hundred kilometers or larger. Recovery of surface mass re-distribution based on GRACE’s time-varying gravity models is applied to studies in solid Earth geophysics, oceanography, climatology and geodesy. At secular time scales, GRACE is expected to provide valuable information on global ice changes, whose variations have profound influences on global climate, and in particular, on sea level changes. At seasonal time scales, GRACE is expected to reveal surface water changes with an ac- curacy of less than 1 cm, or ocean bottom pressure changes with an accuracy of less than 1 mbar (1 mbar =102 Pa). These surface mass redistribution measurements would impove our understanding of the global and regional mass and energy cycles that are critical to human life. Using 15 GRACE monthly gravity models covering the period from April 2002 to December 2003, this study compares seasonal water storage changes recovered from GRACE data and hydrology models at global and regional scales, with particular focus on the Yangtze River basin of China. Annual amplitude of 3.4 cm of equivalent water height change is found for the Yangtze River basin with maximum in Spring and Autumn, agreeing with two state-of-the-art hydrology models. The differences between GRACE re- sults and model predictions are less than 1-2 cm. We conclude that satellite gravimetry has huge potentials in monitering water storage changes in large river basins such as Yangtze.HU Xiaogong1, CHEN Jianli1,2, ZHOU Yonghong1, HUANG Cheng1 & LIAO Xinhao1 1. Center for Astro-geodynamics Research, Shanghai Astronomical Observatory, National Astronomical Observatories, Shanghai 200030, China 2. Center for Space Research, University of Texas at Austin, 3925 W. Braker Lane, Suite 200, Austin, TX78750, USA 2006Science China Earth Sciences2006,49,5:29
11Early J_2 basalts in SE China:Incipience of large-scale late Mesozoic magmatism显示文摘Magmatism in SE China was dormant during 204―180 Ma, but was reactivated in 180― 170 Ma (early J2), and then became more and more intensive towards the end of early Cretaceous. The small-scale early J2 magmatism is the incipience to long-term and large-scale magmatism in this region. A near east-west (EW) trend volcanic belt was distributed across south Hunan, south Jiangxi and southwest Fujian was formed during early J2 time. Along this belt from the inland toward the coast, the lithology of basalts changes from alkali into tholeiite, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. On the basis of geochemical char- acteristics of these basalts, we infer that the melting degree of source rocks and the extent of frac- tional crystallization and crustal contamination all increased whereas the depth of mantle source de- creased from the inland to the coast, which led to the variations of geological characteristics of the volcanic belt. In early J2, the western spreading Pacific plate began to subduct underneath SE China continental block, reactivating near EW trend deep fault that was originally formed during the Indos- inian event. The stress of the western spreading Pacific plate and the extent of asthenosphere up- welling increased from the inland to the coast, which is consistent with the generation and evolution of early J2 basalts.XIE Xin1, XU Xisheng1, ZOU Haibo2, JIANG Shaoyong1, ZHANG Ming3 & QIU Jiansheng1 1. State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China 2. Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA90095-1567, USA. 3. GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, N.S.W. 2109, Australia 2006Science China Earth Sciences2006,49,8:30
12Nature of the Precambrian metamorphic blocks in the eastern segment of Central Tianshan:Constraint from geochronology and Nd isotopic geochemistry显示文摘Granitoid gneisses are widespread in Precambrian metamorphic blocks of eastern segment of the Central Tianshan Tectonic Zone, and they have intrusive contact relationships with their metamorphic sedimentary country rocks of Proterozoic Xingxingxia and Kawabulag groups. Zircon U-Pb ages from a granodioritic gneiss (IW11-1) and a parametamorphic schist (W05-9) are determined at the Weiya area. Euhedral prismatic zircons from the granodioritic gneiss (IW11-1) provide U-Pb isotopic discordia intercept ages of 1218±17 Ma and 426±26 Ma, respectively, and euhedral prismatic zircons from the parametamorphic schist (W05-9) display U-Pb isotopic discordia intercept ages of 1216±74 Ma and 290±15 Ma, respectively. A whole-rock Sm-Nd isotopic isochron is determined in augen granitoid gneiss samples at the Gang- gou-Kumishi area and we obtain the isochron age of 1142±120 Ma, and its ε Nd (t) = -4.3. These geochronological data suggest that these Precambrian metamorphic basement blocks within eastern segment of the Central Tianshan Tectonic Zone can be produced during 1140—1220 Ma, and occur a nearly homochronous metamorphism. Integrated to these geochronological data, Nd depleted mantle model ages (T DM ) and epsilon Nd(t) values of these granitoid gneiss samples indicate that they can derive from mixing in various scales both magmas from mantle and crust sources at a late Mesoproterozoic active continental margin tectonic environment. Similarity in geochronology, Sm-Nd isotopic geochemistry between Weiya-Xingxingxia, Pargangtag and Ganggou-Kumishi areas suggests that they could be a bigger uniform metamorphic basement block, which could be formed by the assembly of the supercontinent Rodinia and be separated by late geological processes.LIU Shuwen,GUO Zhaojie,ZHANG Zhicheng,LI Qiugen & ZHENG Haifei The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,China School of Earth and Space Sciences,Peking University,Beijing 100871,China 2004Science China Earth Sciences2004,47,12:26
13Some basic concepts and problems on the petrogenesis of intra-plate ocean island basalts显示文摘Basaltic magmatism that builds intra-plate ocean islands is often considered to be genetically associated with 'hotspots' or 'mantle plumes'. While there have been many discussions on why ocean island basalts (OIB) are geochemically highly enriched as an integral part of the mantle plume hypothesis, our current understanding on the origin of OIB source material remains unsatisfactory, and some prevailing ideas need revision. One of the most popular views states that OIB source material is recycled oceanic crust (ROC). Among many problems with the ROC model, the ocean crust is simply too depleted (e.g., [La/Sm]PM <1) to be source material for highly enriched (e.g., [La/Sm]PM >> 1) OIB. Another popular view states that the enriched component of OIB comes from recycled continental crust (RCC, i.e.; terrigenous sediments). While both CC and OIB are enriched in many incompatible elements (e.g., both have [La/Sm]PM >>1), the CC has characteristic enrichment in Pb and deletion in Nb, Ta, P and Ti. Such signature is too strong to be eliminated such that CC is unsuitable as source material for OIB. Plate tectonics and mantle circulation permit the presence of ROC and RCC materials in mantle source regions of basalts, but they must be volumetrically insignificant in contributing to basalt magmatism. The observation that OIB are not only enriched in incompatible elements, but also enriched in the progressively more incompatible elements indicates that the enriched component of OIB is of magmatic origin and most likely associated with low-degree melt metasomatism. H2O and CO2 rich incipient melt may form in the seismic low velocity zone (LVZ). This melt will rise because of buoyancy and concentrate into a melt rich layer atop the LVZ to metasomatize the growing lithosphere, forming the metasomatic vein lithologies. Erupted OIB melts may have three components: (1) fertile OIB source material from depth that is dominant, (2) the melt layer, and (3) assimilation of the metasomatic vein lithologies formed earlier in the growing/grown lithosphere. It is probable that the fertile source material from depth may be (or contain) recycled ancient metasomatized deep portions of oceanic lithosphere. In any attempt to explain the origin of mantle isotopic end-members as revealed from global OIB data, we must (1) remember our original assumptions that the primitive mantle (PM) soon after the core separation was compositionally uniform/homogeneous with the core playing a limited or no role in causing mantle isotopic heterogeneity; (2) not use OIB isotopes to conclude about the nature and compositions of ultimate source materials without understanding geochemical consequences of subduction zone metamorphism; and (3) ensure that models and hypotheses are consistent with the basic petrology and major/trace element geochemistry.NIU Yaoling1,2,3 1 Department of Earth Sciences, Durham University, Durham DH1 3LE, UK 2 School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 3 School of Earth and Space Sciences, Peking University, Beijing 100871, China 2009Chinese Science Bulletin2009,54,22:23
14SHRIMP Zircon U-Pb Chronology and Geochemistry of the Henglingguan and Beiyu Granitoids in the Zhongtiao Mountains,Shanxi Province显示文摘Henglingguan 和 Beiyu 变形 granitoids,在 Zhongtiaoshan 前寒武纪的建筑群的西北分布式,包括 trondhjemites 和计算碱的 monzogranites,与太古代的 Zhaizi TTG 片麻岩显示恼人的接触。并且 Beiyu metamorphicgranitoids 主要由 trondhjemites 组成,在 Hujiayu 背斜褶层的核心分布式。分别地,标明日期加权平均值 ~(207 )Pb/~(206 ) Pb 变老的数据表演的新虾锆石 U-Pb 是为 Henglingguan 变形计算碱的 monzogranites 和 Beiyu metamorphictrondhjemites 的 2435.9 Maand 2477 妈并且揭示 600 妈继承了的~ 2 在 magmatic 锆石的核心。Whole-rockgeochemical 数据显示那所有 Henglingguan 和 Beiyu 变形 trondhjemites andcalc 碱的 monzogranites 属于遇见了铝土的中等钾、高钾的 calc-alkalineseries。这些岩石被相对高的全部的碱内容描绘(Na_2O+K_2O,在 to9.08% 上面) ,弄空的 Nb, Ta, P 和 Ti,和衰退权利的 REE 模式与对高 LREEs/HREEsfractionation 中等(吝啬的比率(La/Yb )_n = 25 ) 。在多元素蜘蛛图的 Henglingguan 和 Beiyu metamorphictrondhjemites 显示 negative Rb, Th 和 K 异例由原始披风使正常化。Sm-Nd 同位素的数据表明这些 granitoids 有起始的ε _(Nd ) 到 +2.4 和 Nd 的(t)=-1.2 弄空 T_(MD )= 的披风模型年龄 2622 马马。所有 thesegeochemical 特征显示这些 granitoids 在一条大陆边缘的弧被形成,并且 trondhjemites 主要从少年的部分融化发源玄武岩的材料并且然而, Henglingguan 变形计算碱的 monzogranites 源于在一条大陆边缘的弧下面在古老的外壳中材料再循环。花岗石的岩浆在他们的形成期间经历了污染和分离结晶。YU Shengqiang, LIU Shuwen*, TIAN Wei, LI Qiugen and FENG Yonggang The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education School of Earth and Space Sciences, Peking University, Beijing 100871 2006Acta Geologica Sinica(English Edition)2006,80,6:21
15The use of laser ranging to measure space debris显示文摘Space debris is a major problem for all the nations that are currently active in space.Adopting high-precision measuring techniques will help produce a reliable and accurate catalog for space debris and collision avoidance.Laser ranging is a kind of real-time measuring technology with high precision for space debris observation.The first space-debris laser-ranging experiment in China was performed at the Shanghai Observatory in July 2008 with a ranging precision of about 60-80 cm.The experimental results showed that the return signals from the targets with a range of 900 km were quite strong,with a power of 40W (2J at 20 Hz) using a 10ns pulse width laser at 532 nm wavelength.The performance of the preliminary laser ranging system and the observed results in 2008 and 2010 are also introduced.Zhong-Ping Zhang 1,2,Fu-Min Yang 1,Hai-Feng Zhang 1,Zhi-Bo Wu 1,2,Ju-Ping Chen 1,2,Pu Li 1 and Wen-Dong Meng 1 1 Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China 2 Key Laboratory of Space Object and Debris Observation,Chinese Academy of Science,Nanjing 210008,China 2012Research in Astronomy and Astrophysics2012,12,2:20
16Ultramafic xenoliths in Mesozoic diorite in west Shandong Province显示文摘Ultramafic xenoliths are common in Tietonggou intrusion, Laiwu, Shandong Prov-ince. Peridotite xenoliths develop two-stage metasomatism popularly: (i) The early metasoma-tism is characterized by intergranular clinopyroxene and phlogopite; (ii) The later metasomatism is characterized by orthopyroxene veins with a few plagioclases and amphiboles. These ul-tramafic xenoliths are thought to be mostly from the crust-mantle transitional zone on the basis of their combination, mineral chemistry, equilibrium temperature, and metasomatic characteristics. Major elements, rare earth elements, and Sr-Nd isotopic composition of the ultramafic xenoliths indicate that there is a petrogenetic relationship between the silica-enriched xenoliths and their host diorites. We propose that such silica enrichment might be an indicator of melt-rock interac-tions in the Mesozoic lithosphere beneath western Shandong.CHEN Lihui1,2 & ZHOU Xinhua2 1.The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,China and School of Earth and Space Sciences,Peking University,Beijing 100871,China 2.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China Correspondence should be addressed to Chen Lihui(email: lihui_chen@263.net) 2004Science China Earth Sciences2004,47,6:19
17The δ^(18)O variation of a stalagmite from Qixing Cave,Guizhou Province and indi-cated climate change during the Holocene显示文摘A stalagmite from Qixing Cave, Guizhou Province was dated with the TIMS U-series method and its oxygen isotope composition was analyzed. On the basis of the ages and the variations of the δ18O of the stalagmite, the climate change of the last 7.7 ka has been reconstructed in this area: 7.7-5.8 ka, summer monsoon maximum period; 5.8-3.8 ka summer monsoon weakening period; 3.8-0.15 ka, weakened summer monsoon and high amplitude climate fluctuations period. We put forward that the increasing trend of δ18O of the stalagmite reflected not only the weakening of the summer monsoon, which was caused by the decreasing of solar radiation in the Northern Hemisphere, but also the possibly decreasing contribution of the southwest monsoon to the rainfall of this area. These results are consistent with the output of the numerical climate-model modeling. The high amplitude fluctuation of the δ18O may imply the quick shift of the contributions of different moisture sources to the precipitation in this area.CAI Yanjun, ZHANG Meiliang, PENG Zicheng, LIN Yushi, AN Zhisheng, ZHANG Zhaofeng & CAO YunningState Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710054, China Karst Dynamics Laboratory, Ministry of Land and Resources, Guilin 541003, China Department of Earth and Space Science, University of Science & Technology of China, Hefei 230023, China 2001Chinese Science Bulletin2001,46,22:18
18Re-Os(ICP-MS)dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit显示文摘Massive sulfide ore from the Jinchuan Ni-Cu-PGE deposit was dated by Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron giving an age of 833 ± 35 Ma, initial 187Os/188Os ratio of 0.279 ± 0.018 (MSWD = 1.7) and γOs = 130 ± 15 is obtained. The Re-Os age obtained agrees, within analytical uncertainties, with previous SHRIMP zircon U-Pb age of 827 ± 8 Ma (n=5, MSWD = 4.3). The result suggests that the deposit was formed at Neoproterozoic and that the formation of the Jinchuan Ni-Cu-PGE sulfide deposit may be closely related to the plume activity, which were attributed to the breakup of the Rodinia supercontinent. The high γOs of the massive ores sug-gests that crustal material was involved in the formation of the Jinchuan deposit, however, the quantity of the added crustal material is less than 10%.YANG Gang1,2, DU Andao1, LU Jiren3, QU Wenjun1 & CHEN Jiangfeng2 1. National Research Center of Geoanalysis, Beijing 100037, China 2. Laboratory for Earth Material Cycling, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 3. Institute of Mineral Resource, Chinese Academy of Geological Sciences, Beijing 100037, China 2005Science China Earth Sciences2005,48,10:17
19Relative position determination of a lunar rover using high-accuracy multi-frequency same-beam VLBI显示文摘Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas. In the same-beam VLBI, the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds. The differential phase delay, as the observable of the same-beam VLBI, gives the separation angular information of the two explorers in the celestial sphere. The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth, by using the differential phase delay obtained with the four Chinese VLBI stations. The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m.LIU QingHui1, CHEN Ming1, XIONG WeiMing2, QIAN ZhiHan1, LI JinLing1, HAO WangHong1,4, WANG GuangLi1, ZHENG WeiMin1, GUAN Di3, ZHU RenJie1, WANG WeiHua1, ZHANG XiuZhong1, JIANG DongRong1, SHU FengChun1, PING JinSong1 & HONG XiaoYu11 Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 2 Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China 3 Lunar Explorer Engineering General Department, Chinese Academy of Sciences, Beijing 100012, China 4 Beijing Institute of Tracking and Telecommunications Technology, Beijing 100094, China 2010Science China(Physics,Mechanics & Astronomy)2010,53,3:17
20Significance of native arsenic in the Baogutu gold deposit, western Junggar, Xinjiang, NW China显示文摘Native arsenic together with comb quartz and stibnite is found in the Baogutu gold deposit, western Junggar (Xinjiang), NW China. It is anhedral with various grain size (<0.001 to 2 mm), and contains 98 wt% to 98.7 wt% As. Micro-granular electrum, the main auriferous mineral in the Baogutu gold deposit, is commonly enclosed in or closely accompanied by native arsenic. Three ore-forming paragenetic stages could be identified. Native arsenic mainly formed at stage II which is also the major stage for gold deposition. Mineral assemblage formed at this stage is native arsenic-stibnite-electrum-arseno- pyrite-miargyrite-freibergite-pyrrhotite-pyrite. Based on native arsenic and its coexisting minerals, the temperature (230 to 170℃), oxygen fugacity (logfO2 = -42―-56.5) and sulfur fugacity (logf S2 = -13.3― -16.6) of stage II are estimated. From stage I to stage II, the temperature, sulfur fugacity and S2- concentration of hydrothermal fluid decrease obviously, whereas the As concentration increases. Coexistence with native arsenic of electrum and its contents of 0.5 wt%―1.3 wt% As suggest that As is important to transport Au when S2- concentration decrease in hydrothermal fluid. Crystallization of native arsenic induced the deposition of electrum and consequently the formation of the Baogutu gold deposit.AN Fang & ZHU YongFeng The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education School of Earth and Space Sciences, Peking University, Beijing 100871, China 2009Chinese Science Bulletin2009,54,10:17
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