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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 Geology and Key Laboratory for Continental Dynam- ics of the Education Ministry, Northwest University, Xi’an 710069, China 2. Yunnan geological institute, Kunming 650011, China Department of Geology and Key Laboratory for Continental Dynamics of the Education Ministry Northwest University Xi’an China Yunnan geological institute Kunming China

A response by Han Jian & Hu Shixue to a letter to the editor about their article 'Systematic Position of the Early Cambrian priapulomorph worms' in the 2.04 issue is presented.

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

The upper mantle structure of the Tibetan Plateau and its implication for the continent-continent collision

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Science China Earth Sciences 2005年第8期48卷 1158-1164页

作者： WU Qingju1, ZENG Rongsheng1 & ZHAO Wenjin2.1. institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2. institute of Geology, China Academy of {2. Sciences, Beijing 100037, China institute of Geophysics China Earthquake Administration Beijing China institute of Geology China Academy of Geological Sciences Beijing China

The upper mantle structures of Himalayas-Tibet have been obtained from the mi-gration of receiver functions of the teleseismic events recorded by INDEPTH-III. The result of migration imaging shows a dipping interface subducting northward from the depth of 100 km to the 410-km discontinuity underneath southern Tibet. It indicates that the lithospheric mantle of the Indian continent had been detached from the crust and deeply subducted to the upper mantle of Eurasia during the Indo-Eurasian collision. This kind of continent-continent collision process is fundamentally different from the oceanic collision.

关键词： Tibetan Plateau, receiver function, upper mantle structures, Indo-Eurasian collision, dipping interface.

Lithospheric seismic fabrics of Sulu ultrahigh-pressure metamorphic belt

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Science China Earth Sciences 2005年第5期48卷 585-600页

作者： YANG Wencai 1 , YANG Wuyang 1 , JIN Zhenmin 2.& CHENG Zhenyan 1 1. institute of Geology, Chinese Academy of geological Sciences, Beijing 100037, China 2. China University of Geosciences, Wuhan 430074, China Chinese Academy of geological Sciences Institute of Geology Beijing China China University of Geosciences Wuhan China

Calibration of seismic reflectors appearing in the crust of the Chinese continent sci- entific drilling site can be completed through the correlation studies between direct evidences, such as the drill cores, and geophysical signatures; therefore the interpretation of geophysical data could produce reliable results of crustal structure and composition. On the other hand, there are two Cenozoic volcanoes close to the scientific drilling site; analyzing composition of xenoliths existent in the volcanoes and evaluating their seismic velocities can also offer information about the mantle and lower crust. After the calibration via cores and well-logging data, the seismic re- flectors appearing in the UHP belt can be caused by lithological changes within the UHP rock slice, ductile shearing rock-suites, and later fracture zones. Among these sources, ductile shearing resulted in displacement and detachment of original rock-sheets, producing some rock-interbeds of several hundred meters thick that are named the ductile shearing rock-suites. A suite consists of mylonized gneiss and eclogite slices that underwent shearing, becoming the major mechanism responsible to generate regional strong reflections. The UHP rock-slice is characterized by complicated structures and high density, high seismic velocity and high electri- cal resistivity, its thickness is usually less than 11 km. Velocity and density of the gneiss-layer beneath gradually tend to normal with increasing depth. Based on the xenoliths we can infer that the middle crust contains a lot of gneisses, and the lower crust consists of different granulites. The lithospheric mantle has multi-layer structures and consists mainly of spinal lherzolite and harzburgite, implying late Mesozoic lithospheric thinning. The seismic fabrics with different ori- gins were possible products of different geodynamic processes. For instance, the UHP rock-slice was produced by the UHP metamorphic process and the exhumation of subducted supe

关键词： deep seismic reflection, ultrahigh-pressure belt, Sulu China, calibration of reflectors, lithospheric fabrics.

Kinematics and dynamics of the Mesozoic orogeny and late-orogenic extensional collapse in the Sino-Mongolian border areas

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Science China Earth Sciences 2005年第7期48卷 849-862页

作者： ZHENG Yadong 1 & WANG Tao2.1. Key Laboratory of Orogenic Belts and Crustal Evolution (Peking University), Ministry of Education, Beijing 100871, China 2. institute of Geology, Chinese Academy of geological Sciences, Beijing 100037, China Key Laboratory of Orogenic Belts and Crustal Evolution (Peking University) Ministry of Education Beijing 100871 China institute of Geology Chinese Academy of Geological Sciences Beijinq 100037 China

The Sino-Mongolian border areas underwent two important tectonic events during Mesozoic time after late Paleozoic orogeny: a late Triassic to earlier Jurassic contractional event that resulted in a large-scale south-vergent thrust during the orogeny and a late Jurassic-earlier Cretaceous extensional event in a north-south direction that formed a metamorphic core complex. The kinematic and dynamic analyses show that the thrust sheet moved southwards with a kinematic vorticity number of ca. -0.10 and sub-horizontal maximum compressive stress axis that belongs to a contraction-thickening shear. The upper plate of the late-orogenic detachment relatively moved in a 165°direction. The average kinematic vorticity in its earlier stage was 0.74 that belongs to simple shear dominated shearing and related to the maximum compressive stress axes dipping at ～66°, while the later average kinematic vorticity was ～0.55°that belongs to pure shear dominated shearing with sub-vertical maximum compressive stress axes. This suggests that the thrusting led to the crust thickened and the lower plate rocks that were originally located in the upper crust depressed through a brittle-ductile transition zone into the lower crust and became warmer. The heated rocks trended to uplift since their increasing volume and decreasing density while the loading of the upper-plate rocks increased due to the structural thickening. Under the combined effect of the loading and the thermal-uplifting, the ductile shear zone in between increased in its component of vertical pure shear. Once its pure-shear component exceeded its simple-shear one the ductile shear zone became an extension-thinned shear zone. This progressive transitional process reflects internal and essential temporal and spatial relationships: the extensional factor nucleated during the crust thickening by thrusting and increase of the extensional factor finally led to late-orogenic collapse.

关键词： Mesozoic thrusting,late-orogenic collapse,kinematic vorticity number,stress state.

^(40)Ar/^(39)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance

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Science China Earth Sciences 2004年第9期47卷 794-803页

作者： ZHANG Yueqiao1, CHEN Wen2. 3 & YANG Nong1 1. institute of Geomechanics, Chinese Academy of geological Sciences, Beijing 100081, China 2. institute of Geology, Chinese Academy of geological Sciences, Beijing 100037, China 3. institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 10002., China institute of Geomechanics Chinese Academy of Geological Sciences Beijing China institute of Geology Chinese Academy of Geological Sciences Beijing China institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (12.10 Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 350℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.

关键词： Xianshuihe fault zone, Zheduoshan granitic massif, sinistral shear deformation, 40Ar/39Ar dating, late Cenozoic.

Discovery of double-peaking potassic volcanic rocks in Langshan Group of the Tanyaokou hydrothermal- sedimentary deposit, Inner Mongolia, and its indicating significance

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Science China Earth Sciences 2005年第6期48卷 822-833页

作者： PENG Runmin1, ZHAI Yusheng1, WANG Zhigang2.& HAN Xuefeng2.1. Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology, Ministry of Education, China University of Geosciences, Beijing 100083, China 2. Inner Mongolia geological Prospecting institute, Ministry of Chemical Industry, Hohhot 010074, China Correspondences should be addressed to Peng Runmin Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology Ministry of Education China University of Geosciences Beijing China Inner Mongolia geological Prospecting institute Ministry of Chemical Industry Hohhot China

It is revealed that the protolith of gray-light brown potash-feldspar-leucogranulites and granulites in the 2.d formation of the LG in Tanyaokou deposit are quartz kerotophyre of synsedimentary eruption based on the following facts and features: (1) The rocks look compact and homogeneous without obvious crystals with naked eyes; (2. they contain blastoporphyritic or glomeroporphyritic and blasto-crystalloclastic crystals consisting of quartz with wavy extinction and albite with obvious alteration and deformation; (3) they also contain radiated and fibrous blasto-microspherulitic texture and swallow-tailed bifurcate and blasto-hollow-skeleton crystal texture, representing the rapid cooling characteristic of the magma during submarine volcanic eruption; (4) the major chemical compositions of the rocks are: SiO2.= 70.80%―76.00%, K2. (4.83%―6.2.%)>Na2.(2.78%―3.80%), and K2.+Na2. = 8.63%―9.00%; and (5) their petro-chemical diagrams indicate that they are volcanic rocks. Together with the characteristic that they occur in the same sequence with potassic spilite (SiO2.= 46.12.―50.68%, K2. = 4.2.%―5.93%>Na2. = 2.15%―3.14%, K2.+Na2. = 6.51%―8.08%), it can be confirmed that the vol-canics occurring in the 2.d Formation of the LG in Tanyaokou district are double-peaking potas-sic volcanic rocks. The discovery, together with the tuffs with ore minerals and the distribution of lead isotopic as well as the value of Co/Ni of pyrites >1 showing the obvious endogenic metali-zation, can prove that the Tanyaokou deposit is an untypical SEDEX-type deposit formed in the extension fault basin in the Mesoproterozonic aulacogen of the northern margin of the North China Platform, and its metallogenesis is related to the synsedimentary volcanic activities and the hydrothermal exhalation, and both the ore-forming material source and volcanics came from mantle or lower crust. These facts mentioned above, together with the meta-volcanic rocks (double-peaking) found in the Dongshengmiao and Huog

关键词： extensional rift basin, double-peaking potassic volcanic rocks, Mesoproterozoic, the 2.d formation of LG, Tanyaokou deposit, Inner Mongolia.

Gymnosperms on the eve of the terminal Permian mass extinction in North China and their survival strategies

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Chinese Science Bulletin 1998年第11期43卷 889-897页

作者： WANG Ziqiang+1 and ZHANG Zhiping+2. 1. Tianjin institute of Geology and Mineral Resources, Chinese Academy of geological Sciences, Tianjin 300170, China 2. Tianjin Centre of Physical and Chemical Techniques, Tianjin 300050, China Tianjin institute of Geology and Mineral Resources Chinese Academy of Geological Sciences Tianjin China Tianjin Centre of Phyhical and Chemical Techniques Tianjin China

Main characteristics of the Permian redbed gymnosperms in North China have been summarized: dominant peltasperms and conifers, numerous enigmatics such as Gigantonoclea and Psygmophyllum, and abundant precursors of Mesozoic gymnosperms. Furthermore, stresses affecting these plants survival are suggested to be paleoatmospheric CO-2.concentration, water stress, wind and fire activities, and fungal infection. Consequently, a preliminary analysis accounts for the ecological strategies of these gymnosperms to the P-Tr event.

关键词： North China Permian gymnosperms mass extinction.

Distribution and characteristics of gravelly soil liquefaction in the Wenchuan M_s 8.0 earthquake

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 167-175页

作者： Cao Zhenzhong1,Hou Longqing2.Xu Hongmei2.and Yuan Xiaoming1 1. institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China 2. East China institute of Technology,Fuzhou 344000,China institute of Engineering Mechanics China Earthquake Administration Harbin China East China institute of Technology Fuzhou China institute of Engineering Mechanics Chinese Earthquake Administration Harbin China

In this paper,a distribution map of gravelly soil liquefaction that was caused by the Wenchuan M8.0 earthquake in China is proposed based on a detailed field investigation and an analysis of geological soil profiles. The geological background of the earthquake disaster region is summarized by compiling geological cross sections and borehole logs. Meanwhile,four typical liquefied sites were selected to conduct sample drillings,dynamic penetration tests (DPT),and shear wave velocity tests,to understand the features of liquefied gravelly soil. One hundred and eighteen (118) liquefied sites were investigated shortly after the earthquake. The field investigation showed:(1) sandboils and waterspouts occurred extensively,involving thousands of miles of farmland,12. villages,eight schools and five factories,which caused damage to some rural houses,schools,manufacturing facilities and wells,etc.; (2. the Chengdu plain is covered by a gravelly soil layer with a thickness of 0 m to 541 m according to the geological cross sections; (3) there were 80 gravelly soil liquefied sites in the Chengdu plain,shaped as five belt areas that varied from 2. km to 40 km in length,and about ten gravelly soil liquefied sites distributed within Mianyang area; and (4) the grain sizes of the sampled soil were relative larger than the ejected soil on the ground,thus the type of liquefied soil cannot be determined by the ejected soil. The gravelly soil liquefied sites are helpful in enriching the global database of gravelly soil liquefaction and developing a corresponding evaluation method in further research efforts.

关键词： gravelly soil liquefaction borehole soil profile geological cross section grain size distribution Wenchuan earthquake

Discovery of low grade metamorphic volcanic rock sheets within UHP in Dabie Mts. and its implications

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Chinese Science Bulletin 1997年第14期42卷 1199-1203页

作者： DONG Shuwen, WANG Xiaofeng and HUANG Dezhi1. Chinese Academy of geological Sciences (CAGS), Beijing 100037, China 2. institute of Geomechanics of CAGS, Beijing 100081 China 3. Anhui institute of geological Sciences, Hefei 2.0001 Chinese Academy of geological Sciences (CAGS) Beijing China institute of Geomechmics of CAGS Beijing China Anhui institute of geological Sciences Hefei

THE ultrahigh-pressure metamorphic zone (UHP), outcropping in the central and southernDabie Mts. with an area of about 1000 km^2. may be the largest one in the world. The forma-tion and exhumation mechanism of the UHP rocks become a hot point in the study of continen-tal orogen. The first finding of the Shiqiao structural window, which is composed of low

关键词： ultrahigh-pressure metamorphic zone (UHP) low grade metamorphic rock sheets Dabie Mts.