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Average slip rate, earthquake rupturing segmentation and recurrence behavior on the Litang fault zone, western Sichuan Province, China

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Science China Earth sciences 2005年第8期48卷 1183-1196页

作者： XU Xiwei1. WEN Xueze2. YU Guihua1. ZHENG Rongzhang1. LUO Haiyuan2.& ZHENG Bin2.1. institute of {1., China Earthquake Administration, {2. 1.002., China 2. Earthquake Administration of Sichuan Province, Chengdu 61.041. China 1. institute of{1. China Earthquake Administration 100029 Beijing China 2. Earthquake Administration of Sichuan Province 610041 Chengdu China

The Litang fault zone (LFZ) is an active fault zone within the northwestern Sichuan sub-block. Field investigation reveals new evidence for its late Quaternary offset, neoteric earthquake ruptures and surface-rupturing segmentation, from which long-term slip-rates, char-acteristic earthquake magnitudes and recurrence intervals on the fault zone are estimated. This study shows that the LFZ consists of three subordinate faults, and they are the northern Maoyaba fault, Litang fault and Kangga-Dewu fault, respectively. All of them are dominated by left-lateral strike-slip with reverse dip-slip component on different segments. Based on offset landforms and ages of relevant deposits collected from seven sites, it is estimated that the average left-lateral slip-rate on the LFZ reaches 4.0±1.0 mm/a in the past 1. ka BP, and vertical (reverse) dip-slip rate in the range of 0.1.1.8 mm/a. Three subordinate faults are independent earthquake rup-turing segments, on which the maximum moment magnitude of the characteristic earthquakes is estimated to be 7.0―7.3, and their average recurrence interval to be 500―1.00 a. The latest earthquake ruptures occurred 1.9±2.years ago on the northern Maoyaba fault, about 1.90 AD on the Litang fault, and in 1.48 AD on the Kangga-Dewu fault, and this may indicate a unidirectional migration for surface rupturing earthquakes along the Litang fault zone, related to stress trigger-ing between the segments.

关键词： Litang fault zone, slip rate, earthquake rupturing segmentation, recurrence interval.

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Genesis of ^(2.0)Th excess in basalts from mid-ocean ridges and ocean islands:Constraints from the global U-series isotope database and major and rare earth element geochemistry

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Science China Earth sciences 2010年第10期53卷 1486-1494页

作者： ZHANG GuoLiang1.2.& ZENG ZhiGang1.1.Key Laboratory of Marine {1. and Environment,institute of Oceanology,Chinese {2. of sciences,Qingdao 2.6071.China 2.Graduate University of Chinese {2. of sciences,beijing 1.0049,China 1. Key Laboratory of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Based on 2.0Th-2.8U disequilibrium and major element data from mid-ocean ridge basalts(MORBs) and ocean island basalts(OIBs),this study calculates mantle melting parameters,and thereby investigates the origin of 2.0Th excess.(2.0Th/2.8U) in global MORBs shows a positive correlation with Fe8,Po,Na8,and Fmelt(Fe8 and Na8 are FeO and Na2. contents respectively after correction for crustal fractionation relative to MgO = 8 wt%,Po=pressure of initial melting and Fmelt=degree of melt),while 2.0Th excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle ***,compared with the MORBs,higher(2.0Th/2.8U) in OIBs actually corresponds to a lower melting *** suggests that the 2.0Th excess in MORBs is controlled by mantle melting conditions,while the 2.0Th excess in OIBs is more likely related to the deep garnet *** vast majority of calculated initial melting pressures of MORBs with excess 2.0Th are between 1.0 and 2.5 GPa,which is consistent with the conclusion from experiments in recent years that DU>DTh for Al-clinopyroxene at pressures of >1.0 *** initial melting pressure of OIBs is 2.2.3.5 GPa(around the spinel-garnet transition zone),with their low excess 2.6Ra compared to MORBs also suggesting a deeper mantle ***,excess 2.0Th in MORBs and OIBs may be formed respectively in the spinel and garnet stability *** addition,there is no obvious correlation of K2./TiO2.with(2.0Th/2.8U) and initial melting pressure(Po) of MORBs,so it is proposed that the melting depth producing excess 2.0Th does not tap the spinel-garnet transition *** and MORBs in both(2.0Th/2.8U) vs.K2./TiO2.and(2.0Th/2.8U) *** plots fall in two distinct areas,indicating that the mineral phases which dominate their excess 2.0Th are ***/Yb-Ce curves of fast and slow ridge MORBs are similar,while,in comparison,the Ce/Yb-Ce curve for OIBs shows more influence from *** mechanism

关键词： excess 2.0Th clinopyroxene garnet spinel-lherzolite mid-ocean ridge ocean island

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The control of syndepositional faulting on the Eogene sedimentary basin fills of the Dongying and Zhanhua sags, Bohai Bay Basin

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Science China Earth sciences 2004年第9期47卷 769-782页

作者： LIN Changsong1. ZHENG Herong2. REN Jianye1. LIU Jingyan1.& Qiu Yigang1.1. Department of Energy {1., China University of Geosciences, {2. 1.0083, China 2. Petroleum Exploration and Production institute, Sino-Petroleum and Chemistry Cooperation, {2. 1.0083, China China Univ Geosci Dept Energy Geol Beijing 100083 Peoples R China Sino Petr & Chem Cooperat Petr Explorat & Prod Inst Beijing 100083 Peoples R China

The Dongying and Zhanhua sags are the major hydrocarbon exploration and produc- tion subbasins in the Bohai Bay Basin. Integrated analysis of the sedimentary basin fills has shown that the syndepositional faults and their arrangement styles exerted an important influ- ence on the development and distribution of the Eogene depositional systems. The sedimentary filling evolution of the subbasins reflects the general control of the episodic rifting process. The major long-term active normal faults formed a series of paleogeomorphic accident or slopebreak zones that commonly delineated the subsidiary palaeostructural units and the depositional facies tracts and constrained the general distribution of sedimentary facies zones. The central sag boundary fault slopebreak zones usually determined the distribution of the depocenters of ter- restrial clastic depositional systems, particularly the lowstand fans or deltaic depositional sys- tems, and have proven to be the economically important targets for the exploration of subtle sandstone reservoirs. A variety of syndepositional fault arrangement patterns, including the par- allel, en echelon, combo-like, broom-like fault systems and the fault overlap or transfer zones, have been recognized in the subbasins. They generated distinctive geomorphic features and exerted a direct influence on sediment dispersal and sandbody distribution during the Eogene synrift stage. It is the key for the prediction of depositional systems tracts and reservoir sand- stones to investigate the activity and distribution of the fault slopebreak zones and reconstruct the structural paleogeomorphy in different basin filling stages of the basin evolution.

关键词： episodic rifting, fault slopebreak zone, depositional pattern, Bohai Bay Basin.

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A new method for spatio-temporal prediction of rainfall-induced landslide

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Science China Earth sciences 2006年第4期49卷 421-430页

作者： DING Jixin1.2. YANG Zhifa2. SHANG Yanjun2. ZHOU Shenghua1.& YIN Juntao3 1. China Non-ferrous Metals Resource geological Survey, {1. 1.001.0} China {2. and Geophysics, Chinese academy of sciences, Key Laboratory of Engineering Geomechanics, {1. 1.002., China 3. School of Geoscience & Environmental Engineering, Central South University, Changsha 41.083, China 1. China Non-ferrous Metals Resource geological Survey Beijing 100012 China 2. institute of geology and Geophysics Chinese Academy of Sciences Key Laboratory of Engineering Geomechanics Beijing 100029 China 3. School of Geoscience & Environmental Engineering Central South University Changsha 410083 China

geological condition and rainfall are two most principal conditions inducing landslides in the Chongqing region. By analyzing the forming conditions of rainfall-induced landslides, a new method for spatio-temporal prediction of rainfall-induced landslide is brought forward on the basis of grading and overlapping geological condition and rainfall factor in this paper. At first, semi-quantitative assessment and grading for the geological condition of a certain area or slope can be carried out with the multi-factor interactive matrix. Then the severity of rainfall in that area is grading according to the maximum daily rainfall and the total rainfall in a rainfall course. Finally, the “landslide probability judgement factor” can be worked out through grading and overlapping “geological condition influenc- ing factor” and “rainfall influencing factor”, by which the landslide can be graded into 4 grades, they are landslide extremely easily happening, landslide easily happening, landslide difficultly happening and landslide hardly ever happening respectively. More accurate spatio-temporal prediction of rain- fall-induced landslides can come true on the ground of detailed geological survey of some dangerous slopes in an area and more precise weather forecast. Finally, the reliability and feasibility of carrying out the spatio-temporal prediction of rainfall-induced landslides with the method of “two factors” grading and overlapping are validated by the example of Jipazi landslide.

关键词： rainfall-induced landslide, geological condition, rainfall, two factors, grading and overlapping, interactive matrix, spatio-temporal prediction.

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Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

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Chinese Science Bulletin 2003年第B06期48卷 37-41页

作者： GE Shulan~(1.2.3), SHI Xuefa~1.& HAN Yibing~1.1. Key Laboratory of Marine Sedimentology and Environmental {1., First {1. of Oceanography, State Oceanic Administration. Qingdao 2.6061. China {2. and Geophysics, Chinese academy of sciences, beijing 1.002.. China 3. Graduate School. Chinese academy of sciences, beijing 1.0039. China 1. Key Laboratory of Marine Sedimentology and Environmental geology First Institute of Oceanography State Oceanic Administration 266061 Qingdao China 2. institute of geology and Geophysics Chinese Academy of Sciences 100029 Beijing China 3. Graduate School Chinese Academy of Sciences 100039 Beijing China

The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 1.2.surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe *** L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East China Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are *** the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

关键词：中国黄海表面沉积物磁化率等值线长江黄河旋涡沉积区循环系统

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Characteristics and origins of primary fluids and noble gases in mantle-derived minerals from the Yishu area,Shandong Province,China

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Science China Earth sciences 2006年第1期49卷 77-87页

作者： MA Jinlong1.2. TAO Mingxin2.3 & YE Xianren2.1. Resources and Environmental School, Lanzhou University, Lanzhou 730000, China 2. Key Laboratory of Gas Geochemistry, institute of {1. and Geophysics, Chinese {2. of sciences, Lanzhou 730000, China 3. College of Resources Science & Technology, beijing Normal University, beijing 1.0875, China 1. Resources and Environmental School Lanzhou University Lanzhou 730000 China 2. Key Laboratory of Gas Geochemistry Institute of Geology and Geophysics Chinese Academy of Sciences Lanzhou 730000 China 3. College of Resources Science & Technology Beijing Normal University Beijing 100875 China

Fluids and noble gases of mantle-derived materials are important tracers forthe mantle information. Compositions of primary fluids and noble gases in mantle-derived mineralsfrom the Yishu area, Shandong Province, China, were tested by the methods of heat-bursting andheat-melting respectively. The fluids are mainly composed of CO_2. CO and H_2. which account forabout 90% of the total, and are similar to the mantle-derived rocks from other areas of easternChina; ratios of ~3He/~4He in almost all samples range from 0.82.Ra to 2.74 Ra, whereas^(40)Ar/^(36)Ar from 2.9.5 to 758.8. Both ranges are much lower than those of the typical oceanmantle-derived samples (such as MORB) and primarily reflect the influences of the atmosphericcomponents and the radiogenic isotopes. Ratios of C/~3He range from 2..6 x 1.~9 to 1.50 x 1.~9,N_2.Ar from 92. to 5661.0} and N_2.~3He from 2.5 x 1.~9 to 2. x 1.~9, similar to those in westernUnited States and New Zealand which belong to the tectonic plate collision regions. The ratios fallin the intersect of mantle-crust-atmosphere in the comprehensive tracer-charts, reflecting theinfluences of the atmosphere and the crusts with organic components. Our results suggest that thecomposition of the primary fluids and the isotopic ratios of the noble gases may either reflect theevolution process of mantle-derived rocks connected with the rise and eruption of magma, or theinfluence of the ancient subduction-plate on the continental mantle of this region.

关键词： noble gases, primary fluids, mantle-derived minerals, Yishu area.

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Paleomagnetic dating of the Cenjiawan Paleolithic site in the Nihewan Basin, northern China

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Science China Earth sciences 2006年第3期49卷 295-303页

作者： WANG Hongqiang1.2. DENG Chenglong1. ZHU Rixiang1.& XIE Fei3 1. Paleomagnetism and Geochronology Laboratory (SKL-LE), {1. of {1. and Geophysics, Chinese {2. of Sci- ences, beijing 1.002., China 2. School of the Earth sciences and Resources, China University of Geosciences, beijing 1.0083, China 3. Hebei Province {1. of Cultural Relics, Shijiazhuang 050000, China 1. Paleomagnetism and Geochronology Laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 2. School of the Earth {1. and Resources China University of Geosciences Beijing 100083 China 3. Hebei Province institute of Cultural Relics Shijiazhuang 050000 China

Rock magnetic and magnetostratigraphic investigations on a lacustrine sequence in the Nihewan Basin, northern China, which bears the Cenjiawan Paleolithic site, indicate that the dominant magnetic mineral and remanence carrier contained in the sediments is magnetite. While hematite co-exists with magnetite in some portions of the Cenjiawan sequence, where characteristic remanent magnetizations are carried by both magnetite and hematite. Measurements of anisotropy of magnetic susceptibility confirm that the Cenjiawan sequence has preserved the original sedimentary features and is suitable for magnetostratigraphic study. Paleomagnetic results indicate that the Cenjiawan Paleolithic site is formed just posterior to the Punaruu normal event, which is dated at about 1.1.Ma. Combined with the paleomagnetic results of the Donggutuo, Xiaochangliang and Majuangou sections, it is concluded that early humans were occupying the Nihewan Basin around 1.6, 1.3 and 1.1.Ma. This integrated result is significant to understanding the ability of migration and adaptation to the envi- ronment of early humans.

关键词： Nihewan Basin, Early Pleistocene, Cenjiawan, Paleolithic site, paleomagnetism.

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Quaternary marine transgressions in eastern China

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Journal of Palaeogeography 2012年第2期1卷 105-125页

作者： Lin Jingxing1. 3, Dai Luping2. 3 1. {1. of {1., Chinese {2. of geological sciences, beijing 1.0037, China 2. Key Laboratory of Marine Ecology and Environmental sciences, {1. of Oceanology, Chinese {2. of sciences, Qingdao 2.6071. China 3. College of Earth Science, Graduate University of Chinese {2. of sciences, {1.} 1.0049, China institute of{1. Chinese Academy of Geological Sciences Beijing 100037 China College of Earth Science Graduate University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory of Marine Ecology and Environmental sciences Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China

Based on the data from 1.7 holes (91.1.samples) and the research on ecology and palaeoecology of Foraminifera combined with that on Ostracoda, diatoms, pollen and spores, eight marine transgressions have been recognized in the great plain regions through the Quaternary sequences and two marine transgressions have been found since the Late Pleistocene in the coastal plain (bedrock coast) areas. In the North China Plain, these are in ascending order:the Bohai transgression in the Early Pleistocene, the Haixing and Huanghua transgressions in the Middle Pleistocene, the Baiyangdian and Cangzhou transgressions in the Late Pleistocene, and the Tianjin transgression in the Holocene. In the Yangtze River Delta region the Rugao and Zhoupu transgressions occurred in the Early Pleistocene, the Shanghai, Jiading, and Wangdian transgressions in the Middle Pleistocene, the Jiangyin and Ge Hu transgressions in the Late Pleistocene, and the Zhenjiang transgression in the Holocene. In the coastal plain (bedrock coast) areas of North China, the Cangzhou transgression was recorded in the Late Pleistocene and the Tianjin transgression in the Holocene, whereas in South China the Fuzhou transgression took place in the Late Pleistocene and the Changle transgression in the Holocene. The transgressions correspond to warm periods and regressions to cold periods. The younger transgressions were not only of shorter duration, but also of larger magnitude. These findings point to the existence of four flood event strata since the Middle Pleistocene: two in the late Middle Pleistocene and another two in the Late Pleistocene.

关键词： Quaternary marine transgressions palaeoclimate eastern China

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SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

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Science China Earth sciences 2010年第5期53卷 657-664页

作者： ZHAI QingGuo1.WANG Jun1. LI Cai2.& SU Li3 1.{1. of {1., Chinese {2. of geological sciences, beijing 1.0037, China 2.College of Earth sciences, Jilin University, Changchun 1.0061. China 3 The geological Laboratory Center and State Key Laboratory of geological Processes and Mineral Resources, China University of Geo- sciences, {1.} 1.0083, China 1. institute of{1. Chinese Academy of Geological Sciences Beijing 100037 China2. College of Earth Sciences Jilin University Changchun 130061 China3. The Geological Laboratory Center and State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 1.6Hf/1.7Hf ratios range from 0.2.2.1. to 0.2.2.57, with εHf(t) values of 5.02.0.2., indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

关键词： Qiangtang cumulate gabbro SHRIMP dating Hf isotope

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Response to“Discussion on the systematic position of the Early Cambrian priapulomorph worms”

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Science Bulletin 2006年第2期51卷 250-256页

作者： HAN Jian1.& HU Shixue2.1. Department of {1. and Key Laboratory for Continental Dynam- ics of the Education Ministry, Northwest University, Xi’an 71.069, China 2. Yunnan {1. {2., Kunming 65001., China Department of geology and Key Laboratory for Continental Dynamics of the Education Ministry Northwest University Xi’an China Yunnan geological{1. Kunming China

Due to the combination of complex states of preservation and taphonomies inChengjiang fossils, Huang et al.) expressed different opinions to those of Han et al.) on themorphology and systematic position of the fossil priapulomorph worms (Priapulomorpha) based on theiradditional materials. These diverse opinions are critical in any investigation of the diversity ofthe Introverta in the Cambrian explosion. However, some of their ideas need to be discussed infurther detail.

关键词： Response to Discussion on the systematic position of the Early Cambrian priapulomorph worms

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