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Interactions between hotspots and the Southwest Indian Ridge during the last 90 ma:Implications on the formation of oceanic plateaus and intra-plate seamounts

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Science China Earth Sciences 2011年第8期54卷 1177-1188页

作者： ZHANG Tao 1,2,3,4,LIN Jian 5 & GAO JinYao 3,4 1 Institute of Geodesy and geophysics,Chinese Academy of Sciences,Wuhan 430077,China 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,China 3 The Second Institute of Oceanography,State Oceanic Administrator,Hangzhou 310012,China 4 Key Laboratory of Submarine Geosciences,State Oceanic Administrator,Hangzhou 310012,China 5 department of geology and geophysics,woods hole oceanographic institution,woods hole,ma 0254.,usa 1. Institute of Geodesy and geophysics Chinese Academy of Sciences Wuhan 430077 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. The Second Institute of Oceanography State Oceanic Administrator Hangzhou 310012 China4. Key Laboratory of Submarine Geosciences State Oceanic Administrator Hangzhou 310012 China

This study investigates the relationship between the hotspot-ridge interaction and the formation of oceanic plateaus and seamounts in the Southwest Indian *** first calculated the relative distance between the Southwest Indian Ridge (SWIR) and relevant hotspots on the basis of models of plate reconstruction,and then calculated the corresponding excess magmatic anomalies of the hotspots on the basis of residual bathymetry and Airy *** results reveal that the activities of the marion hotspot can be divided into three main phases:interaction with the paleo-Rodrigues triple junction (73.6-68.5 ma),interaction with the SWIR (68.5-42.7 ma),and intra-plate volcanism (42.7-0 ma).These three phases correspond to the formation of the eastern,central,and western parts of the Del Cano Rise,*** magnitude and apparent periodicity of the magmatic volume flux of the marion hotspot appear to be dominated by the hotspot-ridge *** periodicity of the marion hotspot is about 25 ma,which is much longer than that of the Hawaii and Iceland hotspots (about 15 ma).

关键词： Southwest Indian Ocean hotspot-ridge interaction magmatic volume flux oceanic plateaus seamounts

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Investigation on the Deformation and Failure Patterns of Loess Cut Slope Based on the Unsaturated Triaxial Test in Yan'an,China

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Journal of Earth Science 2024年第1期35卷 235-247页

作者： Lina ma Shengwen Qi Songfeng Guo Qiangbing Huang Xiaokun Hou Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China department of Geological Engineering Chang'an UniversityXi'an 710054China

The large-scale implementation of the Gully Stabilization and Land Reclamation(GSLR)project induces various failures of loess slopes due to excavation in Yan'an,***,the deformation and failure behavior of these excavated loess slopes have not been fully *** this study,field investigation was undertaken for analyzing the distributions and failure features of excavation-induced loess slope *** is found that plastic failure mainly occurs in Q_(3) loess layers and brittle failure in Q_(2).To understand the underlying failure mechanism,a series of triaxial shear tests were conducted on intact Q_(3) and Q_(2) loess samples that with different water contents,namely natural water content(natural),dry side of the natural value(drying 5%),and wet side(wetting 5%).The characteristics of stress-strain curves and failure modes of the samples were *** show that the stress-strain curves of Q_(2) samples are dominated by strain-softening characteristics,while Q_(3) samples mainly exhibit strain-harden features except in the drying ***,shear failures of Q_(3) specimens are mainly caused by shear crack planes(single,X or V-shaped).For Q_(2) loess,the dominance of tensile cracks is observed on the surface of damaged *** disclose the different failure modes of excavated slopes located in different strata,that is,the arc sliding failure of Q_(3) loess slopes and the stepped tensile failure of Q_(2) loess slopes,and are helpful in the design and management of the ongoing GSLR projects in the Loess Plateau.

关键词： loess slope slope stability failure patterns deformation

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Vermiform trace fossils from the Precambrian Ruyang Group, western Henan

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Chinese Science Bulletin 1997年第3期42卷 251-254页

作者： HU Jianmin, MENG Qingren and LI Wenhou1 Xi’ an College of geology, Xi’an 710054, China 2. Institute of geophysics, Chinese Academy of Sciences, Beijing 100101, China 3 department of geology, Northwest University, Xi’an 710069, China Xi’an College of geology Xi’an China Institute of geophysics Chinese Academy of Sciences Beijing China department of geology Northwest University Xi’an China

THE origin and evolution of Precambrian lives has been a long-standing controversial problem. It is now generally accepted by most paleontologists that the origin of metazoa can be traced back to more than 1000 ma, because the Ediacara and latest pre-Ediacara fauna, such as the Huainan fauna, are featured by their diversification of forms, complicated structures

关键词： Precambrian trace fossil Ruyang Group.

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Imaging of echo data of submarine sedimentary beds layer-by-layer with acoustic wave equation refraction correction method

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Chinese Journal of Acoustics 1995年第3期14卷 200-208页

作者： GENG Jianhua ma Zaitian and HUANG Haigui (department of marins geology and geophysics, Tongji University, 200092)

Wide-angle echo data of submarine sedimentary beds are collected by a system composed of a seismic profiler and a hydrophone streamer towed behind the profiler. Usually the wide-angle echo data are processed with common-depth-point stack method to obtain the stacked section for gcological interpretation. When the acoustic velocity of the sedimentary layers has a lateral variation, the stacked section does not represent the real structure of sedimentary layers. Based on this stacked section, we would probably draw a false *** case of knowing the acoustic velocity of sedimentary beds, we may remove the distortions caused by acoustic velocity lateral variations from the stacked section with acoustie wave equation Kirchhoff integration which continues the wave fields in downgoing and upgoing directions respectively. Thus the accurate image of the structure of submarine sedimentary layers is obtained.

关键词： Imaging of echo data Submarine sedimentary bed Refraction correction

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Structural pattern of eastern Himalayan syntaxis in Namjagbarwa and its formation process

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Science China Earth Sciences 2004年第2期47卷 138-150页

作者： ZHANG Jinjiang, Jl Jianqing, ZHONG Dalai, DING Lin & HE Shundong1. department of geology, Peking University, Beijing 100871, China 2. Institute of geology and geophysics, Chinese Academy of Sciences, Beijing 100029, China Correspondence should be addressed to Zhang Jinjiang (email: zhjj@***) 1. department of geology Peking University 100871 Beijing China 2. Institute of geology and geophysics Chinese Academy of Sciences 100029 Beijing China

The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62-60 ma, ~23 ma and ~13 ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology

关键词： Namjagbarwa, eastern Himalayan syntaxis (EHS), structural pattern, formation process, structural chronology.

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Origin of the Red Earth sequence on the northeastern Tibetan Plateau and its implications for regional aridity since the middle Miocene

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Science China Earth Sciences 2006年第5期49卷 505-517页

作者： WANG Xianyan1,7, LU Huayu1,2, JI Junfeg3, WANG Xiaoyong1,7, ZHAO Jingbo4, HUANG Baochun5 & LI Zhen6 1. SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China 2. department of Urban and Resources Sciences, Nanjing University, Nanjing 210093, China 3. department of Earth Sciences, Nanjing University, Nanjing 210093, China 4. department of Geography, Shaanxi Normal University, Xi’an 710062, China 5. Institute of geology and geophysics, Chinese Academy of Sciences, Beijing 100029, China 6 department of Geography, Qinghai Normal University, Xining 810008, China 7. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China 1. SKLLQG Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 7. Graduate School of the Chinese Academy of Sciences Beijing 100039 China 2. department of Urban and Resources Sciences Nanjing University Nanjing 210093 China 3. department of Earth Sciences Nanjing University Nanjing 210093 China 4. department of Geography Shaanxi Normal University Xi’an 710062 China 5. Institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China 6. department of Geography Qinghai Normal University Xining 810008 China

The Red Earth deposit around Xining, northeastern Tibetan Plateau, has beenstudied in terms of soil micro-structure, grain-size distribution, major- and trace-elementchemistry and magne-tostratigraphy. Field investigations indicate that the Red Earth sequenceconsists of 25 visually definable yellow-brown and weakly-developed soils interbedded with reddishstrongly-developed soils, and has a similar structure to the aeolian Red Clay deposit on the ChineseLoess Plateau. Grain-size analysis shows that the Red Earth deposit is very fine-grained with anegligible sand fraction ( > 63 μm). Thin-section observations under light microscopy show that thedeposit has a clayey texture and the coarse fraction ( > 10 μm) mainly consists of quartz,feldspar and micas. Pyroxene and hornblende were also observed. This mineralogical composition ofthe coarse fraction is similar to that of the Quaternary loess. In addition, all of the mineralgrains are semi angular semi-angular and are generally finer than 63 μm. There is a good agreementbetween the major and minor trace element chemistry of loess-soil units and the Red Earth *** REE distributions of the loess-soil and the Red Earth deposit are similar in shape, withenriched LREE and fairly flat HREE profiles and a clear negative Eu anomaly. The geochemicalcharacteristics of the Red Earth deposit are also identical to those of upper continental crust,thus indicating a wind-blown origin. magnetostratigraphic investigation shows that onset of the RedEarth deposition predates 11.4 ma BP (13.6 ma at a nearby site). The distribution of the reportedMiocene aeolian loess at Qin''an of the Loess Plateau is still unknown. Our results indicate thatthis aeolian deposit had extended to the northeastern Tibetan Plateau by at least the middleMiocene. The similarity of the element geochemistry between the Red Earth deposit and the overlyingloess shows that they may have similar sources and dynamic transport system, and may indicate thatthe

关键词： Red Earth deposit, Northeastern Tibetan Plateau, aeolian deposit, aridity of Asia, the middle Miocene.

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CENOZOIC LARGE-SCALE STRIKE-SLIP FAULT IN WEST YUNNAN, CHINA

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地学前缘 2000年第S1期7卷 268-269页

作者： Ji Jianqing 1, Zhong Dalai 2, Sang Haiqing 2, Zhang Liansheng 2[WT5,5”BX](1 department of geology, Peking University, Beijing 100871,China 2.Institute of geology and geophysics, Chinese Academy of Sciences, Beijing 100029,China)

During the collision between India and Eurasia, the continental compression and shorten is thought to be absorbed by the way of thickening of the Tibetan plateau crust and strike\|slip extrusion outwardly of blocks surrounding the Tibetan plateau. A series of models have been proposed recently, of which the most typical one is continental blocks extrusion by Tapponnier et al.. Virtually previous studies show that the Red River—Ailaoshan fault is the eastern boundary of extrusion Indochina displaced southward relative to South China about 23 ma ago, and more, the western boundary of extrusion blocks is inferred to be Sijie fault in the eastern Burma. But the movement age of Sijie fault is around 13 ma inferred from the age of Andeman Sea formation and different from that of the Red River—Ailaoshan fault. It is an important scientific problem where the western boundary of extrusion blocks is.

关键词： the western boundary of extrusion blocks Cenozoic dextral strike\|slip fault deformation age West Yunnan

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Dating of the Karakorum Strike-slip Fault

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Acta Geologica Sinica(English Edition) 2001年第1期75卷 10-18页

作者： ZHOU Yong, XU Ronghua, YAN Yuehua, PAN Yusheng,Tsanyao Frank YANG, Wei LO and WU Chunming Laboratory of Lithosphere Tectonic Evolution, Institute of geology and geophysics, Chinese Academy of Sciences, Beijing 100029department of geology, National Taiwan University, 245 Choushan Road, Taipei 106-17, Taiwandepartment of geology, Chinese Culture University, Hwa-kang, Yang-Ming-Shan, Taipei, Taiwan Institute of geology, Chinese Academy of Geological Sciences, Beijing 100037 Laboratory of Lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 department of geology National Taiwan University 245 Choushan Road Taipei 106–17 Taiwan department of geology Chinese Culture University Hwa-kang Yang-Ming-Shan Taipei Taiwan Institute of geology Chinese Academy of Geological Sciences Beijing 100037 [?]5Zhou Yong male born in 1968 graduated from Chengdu College of geology with a master's degree in 1991. From 1991 to 1995 he focused on ore deposit investigation. Since 1995 he has studied structural geology associated with the Qinghai-Tibet plateau. Tel: (010) 62008438.

This paper mainly discusses the timing of the Karakorum strike-slip fault, and gives a brief introduction of its structures, offset, and deformational style. This fault strikes NNW-SSE. Asymmetrical folds, stretching lineation, S-C fabrics, feldspar and quartz s?-porphyroclasts, domino structure, shear cleavages and faults in the fault zone are products of tectonic movements. They all indicate a dextral slip sense of faulting. Mylonitic bands are widely developed along this fault. Phengite appears, indicating rather high deformational pressure. Geochronological data indicate that the Karakorum strike-slip faulting occurred from 6.88±0.36 to 8.75±0.25 ma. The cumulative displacement from Muztag Ata to Muji is about 135 km.

关键词： Karakorum fault kinematics timing displacement

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Anisotropy of magnetic susceptibility of Hannuoba basalt,northern China:Constraints on the vent position of the lava sequences

Anisotropy of magnetic susceptibility of Hannuoba basalt,nor...

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中国科学院地质与地球物理研究所2003学术年会

作者： Rixiang Zhu and Caidong Shi Institute of geology and geophysics,Chinese Academy of Sciences,Beijing,China Qingsong Liu Institute for Rock magnetism and department of geology and geophysics,University of Minnesota,Minneapolis, Minnesota,usa

Anisotropy of magnetic susceptibility(AMS) was determined for Hannuoba basaltic samples from 17 flows (21.4±0.7ma) distributed in three sections(Jianshaba, Yuershan and manjing) around Zhangbei,northern China. The results show normal‘flow’ fabrics with horizontal foliation *** typical ratios of the principal AMS axes are 1.01 for the magnetic lineation(L) and 1.02 for the foliation(F),*** hysteresis loop, isothermal remanence,thermomagnetic properties,and optical observations indicate that pseudo-single domain (PSD) low-titanium magnetite particles dominate the low-field susceptibility of *** the AMS of the magma at this area is believed to be originated from the lineation of the low-Titanium magnetite particles driven by the lava flow. Since the K trends coincide well with the observed flow directions,the intersection of the mean K trends from: these three sites perfectly defines the previously known vent position of the lava sequences.

关键词： 1518 Geomagnetism and Paleomagnetism:magnetic fabrics and anisotropy 1519 Geomagnetism and Paleomagnetism:magnetic mineralogy and petrology 9604 Information Related to Geologic Time:Cenozoic

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Paleotemperature changes over the past 3000 years in eastern Beijing, China: A reconstraction based on Mg/Sr records in a stalagmite

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Chinese Science Bulletin 2003年第4期48卷 395-400页

作者： ma Zhibang1, LI Hongchun2, XIA Ming1, KU Tehlung2, PENG Zicheng3, CHEN Yushu4 & ZHANG Zhaofeng3 1. Institute of geology and geophysics, Chinese Academy of Sciences, Beijing 100029, China 2. department of Earth Sciences, University of Southern California, Los Angeles, CA90089-0740, usa 3. department of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China 4. Beijing Foshan Tourist Service Centre, Beijing 101201, China Institute of geology and geophysics. Chinese Academy of Sciences Beijing 100029 China

The Mg/Sr ratio in a stalagmite, which is di-rectly proportional to DMg/Ca, the solid-liquid distribution coefficient of Mg, is proposed as a geochemical thermometer to estimate paleotemperature changes. The paleotempera-ture change in eastern Beijing over the past 3000 years has been reconstructed by using this thermometer in the stalag-mite ZFFS-1 from Jingdong Cave. The records can be di-vided into two periods: 3000—2000 aBP, cool and wet, the air temperature averaging 9.8℃; and 2000 aBP—present, hot and dry, the air temperature being 1℃ higher than the mean value (11.7℃) of the past 3000 years. During 500—200 aBP, the air temperature was about 1.2℃ lower than that of the present, corresponding to the Little Ice Age in Europe. Like d 18O and d 13C, Mg/Sr (or DMg/Ca) reflects an obviously warming trend of the past 200 years. These results are sup-ported by historic records.

关键词：北京京东溶洞石笋 Mg/Sr记录古气温测年 3000年

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