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| 1 | Reconstruction of precipitation variation from tree rings in recent 1000 years in Delingha, Qinghai显示文摘Using seven well-replicated Qilian juniper (Sabina przewalskii Kom.) ring-width chronologies developed at Zongwulong and Shalike Mts. in the northeastern part of the Qaidam Basin annual precipitation from previous July to current June in the recent 1000 years was re- constructed for Delingha. The reconstruction can capture 63.1% of precipitation variance and the equation was stable over time. For the reconstructed precipitation, wet periods occurred in AD1520—1633 and 1933—2001, whereas dry intervals in 1429—1519 and 1634—1741. In ad- dition, the magnitude in precipitation variation was lower before 1430 with about 15 mm, but it increased to 30 mm during the period of 1430 to 1850. After 1850, the precipitation variance de- creased again. In contrast to the increase in temperature, a decrease in annual precipitation was evident since the 1990s. The agreement in low-frequency variation between the reconstruction and the glacier accumulation and particulate content in Dunde ice cores during the recent several hundred years suggested that the precipitation reconstructed in this study was rather reliable, and represented a regional signal. This 1000-year reconstruction could benefit our understanding of climatic variation in decadal to century-scale in this region, and provide basic data to climate models and to prediction of future climate in the 21st century. | SHAO Xuemei1, HUANG Lei1, LIU Hongbin2, LIANG Eryuan1, FANG Xiuqi3 & WANG Lili1 1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2. National Climate Center, Beijing 100081, China 3. Beijing Normal University, Beijing 100875, China | 2005 | Science China Earth Sciences2005,48,7: | 113 |
| 2 | 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 |
| 3 | Mesozoic subduction-accretion zone in northeastern South China Sea inferred from geophysical interpretations显示文摘A segment of Mesozoic subduction-accretion zone was inferred across the northeastern South China Sea at approximately NE45° orientation. Basic evidence includes the following: A belt of peek gross horizontal Bouguer gravity gradient (PGHGBA) is comparable in size and intensity to that of the Manila subduction-accretion zone. A belt of high positive magnetic anomalies appears to the north and sub-parallel to the PGHGBA, representing the volcanic arc associated to the subduction zone. The PGHGBA crosses obliquely both Cenozoic structures and present seafloor topography, indicating a pre-Cenozoic age. The segment is offset left-laterally by NW-running strike-slip faults, in concord with the Mesozoic stress field of South China. In addition, the existence of the subduction zone is supported by wide-angle seismic data obtained in different years by different institutions. At approximate localities, a north-dipping ramp of Moho surface is indicated by records of ocean-bottom seismometers, and a strong reflector about 8 km beneath the Moho reflector is indicated by both OBS and long-cable seismic records. The identification of a segment of Mesozoic subduction zone in NE South China Sea fills nicely the gap of the Great Late Mesozoic Circum SE Asia Subduction-acrretion Zone, which extended from Sumatra, Java, SE Kalimantan to N Palawan, and from Taiwan, Ryukyu to SW Japan. | ZHOU Di1, WANG Wanyin2, WANG Jialin3, PANG Xiong4, CAI Dongsheng5 & SUN Zhen1 1. Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guang- zhou 510301, China 2. College of Geological and Topographical Engineering, Chang’an University, Xi’an 710054, China 3. Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 4. China National Offshore Oil Co. Limited – Shenzhen Branch, Shenzhen 518067, China 5. China National Offshore Oil Co. Limited – Research Center, Beijing 100027, China | 2006 | Science China Earth Sciences2006,49,5: | 52 |
| 4 | SHRIMP zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications显示文摘The SHRIMP zircon U-Pb geochronology of three typical samples, including two monzo nitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02DX-137) and southern (20JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 206Pb/238U ages of 229.4 ± 3.0 Ma and 230.4 ± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02DX-95) from the Manghuai Formation give a weighted mean 206Pb/238U age of 231.0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~230 Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 206Pb/238U apparent age of 1977±44 Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of devel- opment of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province. | PENG Touping1,2, WANG Yuejun1, FAN Weiming1, LIU Dunyi3, SHI Yuruo3 & MIAO Laicheng4 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 3. SHRIMP isotope Laboratory, Chinese Academy of Geological Sciences, Beijing 100037, China 4. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China | 2006 | Science China Earth Sciences2006,49,10: | 55 |
| 5 | Mianlüe tectonic zone and Mianlüe suture zone on southern margin of Qinling-Dabie orogenic belt显示文摘The Mianle tectonic zone (Mianle zone), an ancient suture zone in addition to the Shangdan suture in the Qinling-Dabie orogenic belt, marks an important tectonic division geo-logically separating north from south and connecting east with west in China continent. To de-termine present structural geometry and kinematics in the Mianle tectonic zone and to recon-struct the formation and evolution history involving plate subduction and collision in the Qinling-Dabie orogenic belt, through a multidisciplinary study, are significant for exploring the mountain-building orogenesis of the central orogenic system and the entire process of the major Chinese continental amalgamation during the Indosinian. | ZHANG Guowei1, DONG Yunpeng1, LAI Shaocong1, GUO Anlin1, MENG Qingren2, LIU Shaofeng3, CHENG Shunyou1, YAO Anping1, ZHANG Zongqing4, PEI Xianzhi5 & LI Sanzhong6 1. Department of Geology, Northwest University, Xian 710069, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101, China 3. Earth Science and Resource Faculty, China University of Geosciences, Beijing 100083, China 4. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 5. Changan University, Xian 710054, China 6. Qingdao University of Oceanography, Qingdao 266003, China | 2004 | Science China Earth Sciences2004,47,4: | 57 |
| 6 | Geomorphologic evidence of phased uplift of the northeastern Qinghai-Tibet Plateau since 14 million years ago显示文摘A typical sequence of fluvial terraces and aeolian deposits overlying these terraces were multidisciplinary investigated. New evidences for uplift process of the northeastern Qinghai-Tibetan Plateau in the past 14 million years were obtained. At least 11 river terraces along Huangshui, the first-class tributary of Yellow River, at the Xining-Huzhu region are identified. While the first one (T1) is classified as an accumulation terrace, the others are all basement river terraces, which consist of the Tertiary sandstone and siltstone bedrock, fluvial gravel and pebbles and the overlying aeolian loess-Red Clay deposit. Samples from the aeolian deposits were examined for paleomagnetic stratigraphic reconstruction (1030 samples), luminescence dating (16 samples), magnetic susceptibility and grain-size distribution (more than 4000 samples). The luminescence dating and stratigraphic correlation suggest that terraces of T11, T10,T8, T7, T3, T2, T1 were formed at 14, 11.3, 1.55, 1.2, 0.15, 0.07 and 0.01 million years ago, respectively. Sedimentological analysis and geomorphological observation indicate that formation and evolution of these terraces were mainly driven by tectonic uplift. Therefore, the terrace sequence provides an ideal geological record of the uplift process of the northeastern Qinghai-Tibet during the past 14 million years, and the timings of the terraces formation are regarded as the timings of tectonic uplift. The significant uplifting events took place at 14, 11.3, 1.2 and 0.15 million years ago, respectively. The fluvial incision at the Xining-Huzhu region is less than 100 m during a period of ~12 million years in the Miocene era (between the T11 and T9), while the Huangshui River had incised 432 m during the past 1.2 million years (from T7 to the present floodplain). The river incision process clearly demonstrates that accelerated rising of the northeastern Qinghai-Tibet Plateau during the late Cenozoic, and provides new evidence of previous thoughts. There was a significant readjustment of the fluvial catchment during 1.55-1.2 million years ago: before this time, the paleoriver flowed to southwest. After this time the Huangshui River flows to southeast. A tectonic movement dominates reorganization of this fluvial system. | LU Huayu1, WANG Xiaoyong1, AN Zhisheng1, MIAO Xiaodong1, ZHU Rixiang3, MA Haizhou2, LI Zhen4, TAN Hongbing2 & WANG Xianyan1 1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075 China 2. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences. Xining 810008, China 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 4. Department of Geography, Qinghai Normal University, Xining 810008, China | 2004 | Science China Earth Sciences2004,47,9: | 51 |
| 7 | Research on the dynamics of the South China Sea opening:Evidence from analogue modeling显示文摘Independent of Indochina extrusion, the South China Sea experienced a process from passive continental rifting to marginal sea drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32 to 26 Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 24 Ma on, the sea spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South China Sea developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South China Sea evolu- tion. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2 depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South China Sea is accompanied with roughly 15° clockwise rotation, while the SE sub-sea basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground), while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South China Sea might be caused by slab pull from the proto South China Sea subducting toward Borneo and/or mantle flow caused by India-Asia collision. | SUN Zhen1,2, ZHOU Di1, ZHONG Zhihong3, XIA Bin2, QIU Xuelin1, ZENG Zuoxun4 & JIANG Jianqun5 1. CAS Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China 2. CAS Key Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 3. Department of Technology, Shenzhen Branch of CNOOC, Guangzhou 510240, China 4. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 5. Hainan Oil & Gas Exploration Company, Liaohe Oilfield PetroChina, Panjin 124010, China | 2006 | Science China Earth Sciences2006,49,10: | 45 |
| 8 | Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau显示文摘Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the per- mafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively serious degradation. Furthermore, from the angles of grassland coverage and biological production the variation characteristics of high-cold eco- systems in different representative regions and different geomorphologic units under different climatic conditions were quantitatively assessed. In the future, adopting effective measures to protect permafrost is of vital importance to maintaining the stability of permafrost engineering and alpine cold eco- systems in the plateau. | WANG Genxu1,3 , LI Yuanshou2 , WU Qingbai2 & WANG Yibo3 1. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China 2. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 3. Resource and Environment School, Lanzhou University, Lanzhou 730000, China | 2006 | Science China Earth Sciences2006,49,11: | 41 |
| 9 | 套管磨损机理及其防磨措施研究显示文摘在大位移井、大斜度井、水平井和深井钻井中 ,或者在狗腿严重度较大的井段以及在技术套管下入后的长裸眼钻井过程中 ,常常出现套管磨损问题。由此而诱发的套管抗挤强度和抗内压强度降低问题影响了油气井的后续完井测试作业、降低了油气井寿命 ,严重时还会导致某段油气井报废或整口油气井报废。为此 ,文章提出分别以水基泥浆、油基泥浆、清水作为润滑介质 ,用实验手段分别研究了法向载荷、温度、转盘转速、摩擦副材料特性对套管磨损的影响。同时 ,在对国内外防磨措施进行研究后 ,指出敷焊耐磨带是一种经济可行的防磨措施 ,在深井钻井、大位移井钻井和大斜度钻井中应重点推广。 | 林元华 3.付建红 施太和 严仁俊 贺志刚 董伟 李润方 | 2004 | 天然气工业2004,24,7: | 49 |
| 10 | Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring显示文摘The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean me- ridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres. | FAN Ke1,2,3 & WANG Huijun2 1. Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2. Department of Atmospheric Science, Yunnan University, Kunming 650091, China 3. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China | 2006 | Science China Earth Sciences2006,49,5: | 36 |
| 11 | A three-dimensional variational ocean data assimilation system:Scheme and preliminary results显示文摘A new 3DVAR-based Ocean Variational Analysis System (OVALS) is developed. OVALS is capable of assimilating in situ sea water temperature and salinity observations and satellite altimetry data. As a component of OVALS, a new variational scheme is proposed to assimilate the sea surface height data. This scheme considers both the vertical correlation of background errors and the nonlinear temperature-salinity relationship which is derived from the generalization of the linear balance constraints to the nonlinear in the 3DVAR. By this scheme, the model temperature and salinity fields are directly adjusted from the altimetry data. Additionally, OVALS can assimilate the temperature and salinity profiles from the ARGO floats which have been implemented in recent years and some temperature and salinity data such as from expendable bathythermograph, moored ocean buoys, etc. A 21-year assimilation experiment is carried out by using OVALS and the Tropical Pacific circulation model. The results show that the assimilation system may effectively improve the estimations of temperature and salinity by assimilating all kinds of observations. Moreover, the root mean square errors of temperature and salinity in the upper depth less than 420 m reach 0.63℃ and 0.34 psu. | ZHU Jiang1,2, ZHOU Guangqing1, YAN Changxiang1, FU Weiwei1 & YOU Xiaobao1,3 1. International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 2. Jiangsu Key Laboratory of Meteorological Disaster, Nanjing University of Information Science and Technology, Nanjing 210044, China 3. Beijing Institute of Applied Meteorology, Beijing 100029, China | 2006 | Science China Earth Sciences2006,49,11: | 35 |
| 12 | Petrogenesis and dating of the Kangding complex,Sichuan Province显示文摘An analysis of major and trace element geochemistry and SHRIMP U-Pb zircon dating of mafic, intermediate, and felsic rocks from the Mianning metamorphic complex of Si- chuan Province was conducted. One of our conclusions is that a majority of the zircons crystal- lized between 721 and 773 Ma in a magmatic regime. The complexes contain early to late Pa- leo-proterozoic relict zircons from ancient continental crust. The oldest age, 2468 Ma, may rep- resent the basement of the Yangtze block. Overgrowth zircon rims and palingenetic zircons have been observed and dated, and are believed to have formed after crystallization, during Paleozoic and Mesozoic metamorphic-anatexis. We also conclude that depletion of Nb, Ta, HREE, in a spider-diagram normalized to primitive mantle and calc-alkaline association, implies that they formed in island-arc or under-plating settings. | CHEN Yuelong 1 , LUO Zhaohua 1 , ZHAO Junxiang, LI Zhihong, ZHANG Hongfei & SONG Biao 3 1. Faculty of Earth Sciences and Natural Resources, China University of Geosciences, Beijing 100083, China 2. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 3. Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China | 2005 | Science China Earth Sciences2005,48,5: | 40 |
| 13 | Ultrahigh pressure (>7 GPa) gneissic K-feldspar (-bearing) garnet clinopyroxenite in the Altyn Tagh, NW China: Evi- dence from clinopyroxene exsolution in garnet显示文摘The exsolution of clinopyroxene and rutile in coarse-grain garnet is found in the gneissic K-feldspar(-bearing) garnet clinopyroxenite from Yinggelisayi in the Altyn Tagh, NW China. The maximum content of the exsolved clinopyroxene in the garnet is up to >5% by volume. The reconstructed precursor garnet (Grt1) before exsolution has a maximum Si content of 3.061 per formula uint, being of supersilicic or majoritic garnet. The peak-stage metamorphic pressure of >7 GPa is estimated using the geobarometer for volume percentage of exsolved pyroxene in garnet and the Si-(Al+Cr) geobarometer for majoritic garnet, and the temperature of about 1000℃ using the ternary alkali-feldspar geothermometer and the experimental data of ilmen- ite-magnetite solid solution. The protoliths of the rocks are intra-plate basic and intermediate ig- neous rocks, of which the geochemical features indicate that they are probably the products of the evolution of basic magma deriving from the continental lithosphere mantle. The rocks are in outcrops associated with ultrahigh pressure garnet-bearing lherzolite and ultrahigh pressure garnet granitoid gneiss. All of these data suggest that the ultrahigh pressure metamorphic rocks in the Altyn Tagh are the products of deep-subduction of the continental crust, and such deep- subduction probably reaches to >200 km in depth. This may provide new evidence for further discussion of the dynamic mechanism of the formation and evolvement of the Altyn Tagh and the other collision orogenic belts in western China. | LIU Liang1,3, CHEN Danling1, ZHANG Anda1, SUN Yong1, WANG Yan1, YANG Jiaxi1,2 & LUO Jinhai1 1. Key Laboratory of Continental Dynamics of the Ministry of Education of China, Northwest University, Xi’an 710069, China 2. College of Earth Science and Land Resources, Chang’an University, Xi’an 710054, China 3. The Laboratory of Orogen and Basin of the Ministry of Education, Peking University, Beijing 100871, China | 2005 | Science China Earth Sciences2005,48,7: | 38 |
| 14 | The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan,Yunnan显示文摘The fault belts in Sanjiang mainly include Jinshajiang-Honghe fault, Lancangjiang fault and Nujiang fault (called Sanjiang faults) in western Yunnan Province, China. By interpreting the wide-angle seismic reflection/refraction profile between Zhefang and Binchuan, which crosses Tengchong and Baoshan blocks in Dianxi (western Yunnan) tectonic zone, we recon- struct the crustal structure with seismic traveltime tomography for crustal P-wave velocity and the seismic scattering image for crustal seismic reflection structure. In this paper, we firstly present the crustal structure images of P-wave velocity and seismic reflection under the wide-angle seismic profile. These results demonstrate that, the crustal velocity structure and seismic reflec- tion structure along the profile can be divided into 3 segments, and there is an obvious difference of crustal structure among the eastern, the western and the middle segment. Generally, crustal P-wave velocities in the Baoshan segment are 0.1―0.2 km/s slower and seismic reflection am- plitudes from Moho discontinuity are stronger than the other 2 segments. In the studied area, crustal thickness is about 40 km, and shows the thickening tendency from west to east along the profile. Additionally, it can be seen that there is one strong-amplitude seismic reflection event as bright points at the depths of 8―10 km, along the segment of 80―115 km of the profile (south- ward of Tengchong); and seismic reflection wave-field from Moho discontinuity varies obviously along the lateral direction. Finally, we make some discussions on the crustal thickening pattern in the Sanjiang fault belt, structural environment of earthquake development and the contact rela- tionship between the Tengchong block, Banshan block and Luxi trough. | ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3, LI Jiliang1, LIU Yifeng1 & LIU Zhenkuan4 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2. Institute of Geophysics, China Seismological Bureau, Beijing 100085, China 3. Institute of Deposition Resource, Chinese Academy of Geosciences, Beijing 100037, China 4. School of Exploration and Information, China University of Geosciences, Beijing 100083, China | 2005 | Science China Earth Sciences2005,48,9: | 39 |
| 15 | Carbon isotope composition of the Lower Triassic marine carbonates, Lower Yangtze Region, South China显示文摘Studies on three Lower Triassic sections located on the shallow water platform, the deep water slope and in the deep water basin in the Lower Yangtze Region, South China, show the similar trend of carbon isotope evolution. Biostratigraphic correlations among the Lower Triassic sections on the basis of standard conodont zones indicate that three negative shifts occurred in the Griesbachian, the Smithian and the late Spathian stages respectively, and one distinctly positive shift occurred in the early Spathian stage. Trend of carbon isotope evolution of the Lower Triassic reflects some significant changes in the global carbon cycle. Moreover, δ 13C background values are intensively controlled by palaeogeographic environment. In general, δ 13C values from deep-water slope carbonates are lighter than those from carbonate platform and heavier than those from deep-water basin carbonates. The positive carbon isotope excursion may be induced by a significant amount of organic carbon burial in marine sediments and increase in primary productivity. The large negative carbon isotope excursions during the Early Triassic in Lower Yangtze Region are interpreted to relate to volcano eruptions based on tuffaceous claystone interlayers observed near the Permian-Triassic boundary, the Induan- Olenekian boundary and the Lower Triassic-Middle Triassic boundary. | ZUO Jingxun1,2, TONG Jinnan3, QIU Haiou4 & ZHAO Laishi3 1. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China 2. Henan Institute of Geological Survey, Zhengzhou 450007, China 3. State Key Laboratory of Geological Processes and Mineral Resources at China University of Geosciences, Wuhan 430074, China 4. Faculty of Material Sciences and Chemical Engineering, China University of Geosciences, Wuhan 430074, China | 2006 | Science China Earth Sciences2006,49,3: | 32 |
| 16 | Grain-size features of a Miocene loess-soil sequence at Qinan: Implications on its origin显示文摘In this study, grain-size of 507 bulk samples from the QA-I Miocene loess-soil sequence at Qinan were analyzed, and the grain-size features are compared with those of typical Quaternary loess and soil samples, representative lacustrine and fluvial samples. The results indicate that the grain-size distribution pattern of the Miocene loess is essentially similar to that of Quaternary loess, but greatly differs from the lacustrine and fluvial sediments. Loess layers are regularly coarser than soil layers, indicating cyclical climate changes. Median grain-size along the 253.1 m sequence varies from 6 to 13 μm and the >63 μm fraction represents only 5.3% in maximum, 0.9% in average. Long-term grain-size variations are consistent with the loess accumulation rate at Qinan and with the eolian mass accumulation rate in the North Pacific. These features firmly indicate an eolian origin of the studied sequence, and also reveal a coeval changes between the long-term changes of eolian grain-size and continental aridity in the dust source regions. | QIAO Yansong1,3, GUO Zhengtang2,1, HAO Qingzhen1, YIN Qiuzhen1, YUAN Baoyin1 & LIU Tungsheng1 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2. Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China 3. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China | 2006 | Science China Earth Sciences2006,49,7: | 33 |
| 17 | A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin显示文摘The surface water and groundwater are important components of water cycle, and the interaction between surface water and groundwater is the important part in water cycle research. As the effective tracers in water cycle research, environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively. The study area is the Huaisha River basin, which is located in Huairou district, Beijing. The field surveying and sampling for spring, river and well water were finished in 2002 and 2003. The hydrogen and oxygen isotopes and water quality were measured at the laboratory. The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed. The altitude effect of oxygen isotope in springs was revealed, and then using this equation, theory foundation for deducing recharge source of spring was estimated. By applying the mass balance method, the annual mean groundwater recharge rate at the catchment was estimated. Based on the groundwater recharge analysis, combining the hydrogeological condition analysis, and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin, part of the runoff in the Huaisha River basin is recharged outside of this basin, in other words, this basin is an un-enclosed basin. On the basis of synthetically analyses, combining the compositions of hydrogen and oxygen isotopes and hydrochemistry, geomorphology, geology, and watershed systems characteristics, the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated, and the interaction between surface water and groundwater was re- vealed lastly. | SONG Xianfang1, LIU Xiangchao1, 2, XIA Jun1, YU Jingjie1 & TANG Changyuan1, 3 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Re- sources Research, Chinese Academy of Sciences, Beijing 100101, China 2. College of River and Ocean, Chongqing Jiaotong University, Chongqing 400074, China 3. Chiba University, Chiba 263-8522, Japan | 2006 | Science China Earth Sciences2006,49,12: | 34 |
| 18 | Development of distributed time-variant gain model for nonlinear hydrological systems显示文摘In this paper, a rainfall-runoff modeling system is developed based on a nonlinear Volterra functional series and a hydrological conceptual modeling approach. Two models, i.e. the time-variant gain model (TVGM) and the distributed time-variant gain model (DTVGM) that are built on the platform of Digital Elevation Model (DEM), Remote Sensing (RS) and Unit Hydro-logical Process were proposed. The developed DTVGM model was applied to two cases in the Heihe River Basin that is located in the arid and semiarid region of northwestern China and the Chaobai River basin located in the semihumid region of northern China. The results indicate that, in addition to the classic dynamic differential approach to describe nonlinear processes in hy-drological systems, it is possible to study such complex processes through the proposed sys-tematic approach to identify prominent hydrological relations. The DTVGM, coupling the advan-tages of both nonlinear and distributed hydrological models, can simulate variant hydrological processes under different environment conditions. Satisfactory results were obtained in fore-casting the time-space variations of hydrological processes and the relationships between land use/cover change and surface runoff variation. | XIA Jun1, 2, WANG Gangsheng1, TAN Ge1, YE Aizhong2 & G. H. Huang3 1. Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2. State Key Laboratory of Water Resources & Hydropower Engineering Sciences, Wuhan University, Wuhan 430072, China 3. Faculty of Engineering, University of Regina, 3737 Wascana Parkway, Regina, Sask., S4S 0A2, Canada Correspondence should be addressed to Xia Jun | 2005 | Science China Earth Sciences2005,48,6: | 32 |
| 19 | Contemporary crustal movement of continental China obtained by global positioning system(GPS) measurements显示文摘We obtain a unified horizontal velocity field of continental China and vicinity through measurements at 81 GPS stations provided by the National Key Infrastructure Project, Crustal Movement Observation Network of China. The velocity field delineates patterns of movements and deformation of active crustal blocks in continental China under the Eurasia-fixed reference frame. The space-based geodesy also clearly shows for the first time the horizontal movementand deformation of continental China induced by indentation of the Indian plate. The data provide kinematic constraints for simulating dynamic process of continental litho-spheric deformation. | MA Zongjin, CHEN Xinlian, YE Shuhua, LAI Xian, WEI Ziqing, CHEN Junrong, NING Jinsheng, XU Huoze & DING Guoyu1. Insitute of Geology, China Seismological Bureau, Beijing 100029, China (e-mail: disgroup@publi.bta.net.cn)2. Center for Analysis and Prediction, China Seismological Bureau, Beijing 100036, China 3. Shanghai Astronomic Observatory, Chinese Academy of Sciences, Shanghai 200030, China 4. Institute of Seismology, China Seismological Bureau, Wuhan 430077, China 5. Institute of Survey and Mapping, Xi’an 710054, China 6. National Bureau of Survey and Mapping, Beijing 100830, China 7. Wuhan University, Wuhan 430077, China 8. Institute of Geodesy and Geophysics, Wuhan 430077, China 9. China Seismological Bureau, Beijing 100036, China | 2001 | Chinese Science Bulletin2001,46,18: | 34 |
| 20 | Early 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 | 2006 | Science China Earth Sciences2006,49,8: | 30 |