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Discovery of eclogite and its geological significance in Qiangtang area, central Tibet

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Science Bulletin 2006年第9期51卷 1095-1100页

作者： LI Cai1, ZHAI Qingguo2. DONG Yongsheng1 & HUANG Xiaopeng11. College of Earth sciences, Jilin University, Changchun 130061, china {2., chinese academy of geological sciences, Bei- jing 100037, china College of Earth sciences Jilin University Changchun 130061 China institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

Eclogite is first discovered from Qiang- tang area, central Tibet, which occurs as a lens in the high-pressure metamorphic belt comprising glauco- phane-muscovite schist and garnet-muscovite schist, along the south margin of Lungmu Co-Shuanghu Paleo-Tethys suture. A glaucophane 40Ar/39Ar age of 2.0 Ma and a phengite 40Ar/39Ar age of 2.1.9 Ma have been obtained from blueschists associated with eclogite. The rock consists of garnet, omphacite, amphibole, phengite, and rutile, etc, and the jadeite content in omphacite ranges from 32.7% to 38.95%. It is estimated that the temperature of the eclogite is 2.35 GPa. The discovery of Qiangtang ecologite fur- ther supports that there is a suture zone of Indo- chinese epoch in central Qiangtang area, and is very important for discssing the evolution of the pa- leo-ocean and paleo-plate tectonics in this area.

关键词： Qianghai-Tibet Plateau Qiangtang eclogite tectonics.

Changchengite—A New Iridium Bismuthide-Sulphide from the Yanshan Mountains

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Acta Geologica Sinica(English Edition) 1997年第4期71卷 486-490,514页

作者： Yu Zuxianginstitute of geology,{2., 2. Baiwanzhuang, beijing 100037

Changchengite occurs in chromite orebodies in dunite and in platinum placer deposits in chromite orebodies nearby. The mineral occurs as massive aggregates or veinlets on margins of iridisite (IrS2. and replaces it. Opaque. Lustre metallic. Colour steel-black. Streak black. Hm = 3.7. VHN2.= 165 kg/ mm2. Isotropic. Cleavage none. Density 11.96 g/ cm3. Seven electron microprobe analyses give the following mean chemical results (wt. %): S 7.2. Cu 0.3, Te 0.4, Ir 41.2. Pt 2.8 and Bi 47.3 with total 99.1. The simplified formula is IrBiS. The strongest X-ray powder diffraction lines (hkl, d, I) are 2.0, 2.75 (70); 2.1, 2.51 (60); 311, 1.860 (100); 440. 1.090 (50) and 600, 1.02. (50). The X-ray powder diffraction pattern is similar to that of mayingite. After the diffraction data are indexed the mineral is determined to be cubic. The space group is P2.3 with a = 0.6164(4) nm, V = 0.2.42.nm3 and Z = 4.

关键词： changchengite new mineral new iridium bismuthide-sulphide Yanshan Mountains chromite ore body platinum placer deposit

Petrology of the Non-mafic UHP Metamorphic Rocks from a Drillhole in the Southern Sulu Orogenic Belt,Eastern-Central china

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Acta Geologica Sinica(English Edition) 2003年第2期77卷 173-186页

作者： ZHANG Zeming, XU Zhiqin and XU Huifeninstitute of geology,{2., 2. Baiwanzhuang Rd., beijing 100037 E-mail: zzm@***. chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

The Drillhole ZK703 with a depth of 558 m is located in the Donghai area of the southern Sulu ultrahigh-pressure (UHP) metamorphic belt, eastern china, and penetrates typical UHP eclogites and various non-mafic rocks, including peridotite, gneiss, schist and quartzite. Their protoliths include ultramafic, mafic, intermediate, intermediate-acidic, acidic igneous rocks and sediments. These rocks are intimately interlayered, which are meters to millimeters thick with sharp and nontectonic contacts, suggesting in-situ metamorphism under UHP eclogite facies conditions. The following petrologic features indicate that the non-mafic rocks have experienced early-stage UHP metamorphism together with the eclogites: (1) phengite relics in gneisses and schists contain a high content of Si, up to 3.52.p.f.u. (per formula unit), while amphibolite-facies phengites have considerably low Si content (2. p.f.u.); (2. jadeite relics are found in quartzite and jadeitite; (3) various types of symplectitic coronas and pseud

关键词： UHP metamorphism non-mafic rock drillhole Dabie-Sulu orogenic belt eastern-central china

Ambient noise near the sea-route

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 40-45页

作者： HE Li1,2. LI ZhengLin1,3 & PENG ZhaoHui1 1 National Laboratory of Acoustics, institute of Acoustics, chinese {2. of sciences, beijing 100190, china 2.institute of geology and Geophysics, chinese {2. of sciences, beijing 10002., china 3 NanHai Laboratory of Acoustics, institute of Acoustics, chinese {2. of sciences, Haikou 5702.6, china National Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing China institute of geology and Geophysics Chinese Academy of Sciences Beijing China NanHai Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Haikou China

Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

关键词： ambient noise model horizontal correlation discrete ships

Event Stratigraphy, Biostratigraphy and Sequence Stratigraphy of Neoproterozoic in North china

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Journal of Earth Science 1999年第2期18卷 3-11页

作者： Qiao Xiufu Gao Linzhi Gao Mai institute of geology,{2., beijing 100037

The aim of this study is to discuss the chronostratigraphy, catastrophic event stratigraphy, biostratigraphy and sequence stratigraphy of Neoproterozoic. In the eastern part of the North china, the Neoproterozoic consists of Qingbaikou System (1 000-800 Ma) and Sinian System (800-600 Ma). The Qingbaikou System is widely distributed over the whole area and the Sinian System only in the eastern and southern parts of the plate. In this paper, we discuss the age limit of the formations, and try to establish the Neoproterozoic chronostratigraphic frame, the ages of which are partly based on recently obtained carbonate whole rock Pb Pb isotope. Based on the event records of ancient earthquake, which are well developed in Sinian carbonates, “a vibrational liquefaction seismic sequence” in carbonate rocks is established. We propose a time correlation for the Sinian formation in eastern North china, on the bases of event records of earthquake in combination with biostratigraphy, and thus revise the traditional correlation scheme that has been used for nearly 30 years. Some biostratigraphic results were obtained in fossil microplants, megafossils and metazoans in North china. A large amount of big double layered and complex ornamented acritarchs are found in Qingbaikou and Sinian systems. On the basis of the correlation by earthquake events, the Huainan fauna is regarded as Late Sinian, probably between 700 Ma and 600 Ma. Altogether 16 depositional sequences are distinguished in the Neoproterozoic, with an average time interval of about 15-16 Ma.

关键词： catastrophic event stratigraphy biostratigraphy sequence stratigraphy Neoproterozoic North china.

Structures and physical properties of rigid polyurethane foams with water as the sole blowing agent

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Science china Chemistry 2006年第4期49卷 363-370页

作者： LI Xiaobin1,2. CAO Hongbin1 & ZHANG Yi1 1. institute of Process Engineering, chinese {2. of sciences, beijing 100080, china 2. Graduate School of the chinese {2. of sciences, beijing 100039, china institute of Process Engineering Chinese Academy of Sciences Beijing China Graduate School of the chinese academy of {2. Beijing China

Rigid polyurethane foams blown by varying water level were prepared in this study. The structures and physical properties of rigid polyurethane foams blown by water were measured with FT-IR, universal testing machine (Instron3365), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The results show that polyurea and polybiuret were the typical charac- teristics, and the cream time and gel time were shorter for the fully water blown rigid foams than that for the fully cyclopentane blown foams. The density of foam samples decreased from 45.0 kg/m3 to 2..4 kg/m3 with the increase of water level from 3 pph to 7 pph. Compressive strength exhibited the similar behavior with density. The average cell size of foam samples ranged from 2.1 μm to 356 μm with the increase of water level from 3 pph to 7 pph, respectively. At the same time, poorer dimen- sional stability was encountered with the increase of average cell size due to fast diffusion rate of CO2.out of the foam. The results of thermal analysis show that the glass transition temperature (Tg) shifted to a higher temperature with the increase of isocyanate level when more water was used as chemical blowing agent.

关键词： polyether polyol, polyurethane rigid foam, compressive strength, dimensional stability, cell size, glass transition temperature.

Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media(Ⅱ)

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 422-430页

作者： CAI Ruixian1, GOU Chenhua1, 2.& ZHANG Na1 1. institute of Engineering Thermophysics, chinese {2. of sciences, beijing 100080, china 2. Graduate School, chinese {2. of sciences, beijing 100080, china institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model―an improved Darcy model―describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.

关键词： explicit analytical solution, porous medium, natural convection, Brinkman model, anisotropic.

^(40)Ar/^(39)Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai, East china

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Acta Geologica Sinica(English Edition) 2003年第2期77卷 155-168页

作者： LI Jinyi, YANG Tiannan, CHEN Wen and ZHANG Sihong institute of geology,{2., beijing 100037E-mail: jyli@*** chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East china underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 2.8.0±2.9 Ma and isochron age of 2.9.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 2.0 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 2.3.1±0.3 Ma and isochron age of 2.3.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 2.3.4±0.3 Ma, 2.3.6±0.4 Ma and 2.4.8±2.2.Ma, and isochron ages of 2.4.0±2.0 Ma, 2.0.6±3.1 Ma and 2.4.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 2.4 Ma). The integration of these data with previous chronological ages on the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about 2.0 Ma) to the lower crust (at the depth of about 2.-30km at 2.0 Ma), and at the rate of 1-2.km/Ma to the middle crust (at the depth of about 15 km at 2.3 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km

关键词： ultrahigh-pressure metamorphic rocks structural deformation 40Ar/39Ar dating exhumation Donghai East china

The Coexisting Clinopyroxene-Garnet Acidometer and Acidity Facies of Skarn Deposits

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Acta Geologica Sinica(English Edition) 1990年第3期64卷 299-308页

作者： Lin Wenwei institute of Mineral Deposits, chinese academy of geological sciences, {2. Liu Linqun institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing

On the basis of geological studies of skarn deposits in china and by using thermodynamic models of thesolid solution, the coexisting clinopyroxene-garnet pair in skarn deposits has been analysed and a coexistingclinopyroxene-garnet acidometer developed. They can be used to estimate the medium condition under whichthe skarn was formed. The research on the acidity for the formation of various metallic skarn deposits in chinasuggests that skarns endowed with dissimilar types of mineralization and occurring in diverse environments dif-fer in the acidity conditions for their formation and in the trend of acidity variation of ore-bearing fluid. This,coupled with the study of oxygen fugacity of coexisting minerals, makes it possible to establish the oxygenfugacity-acidity facies of skarn deposits, which reflect the close genetic relationship between the metallizationand the formation of skarn.

关键词： OH The Coexisting Clinopyroxene-Garnet Acidometer and Acidity Facies of Skarn Deposits