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Relation between texture and chemical composition of peridotite xenoliths and its implications: An example from Wangqing, Jilin Province

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chinese Science Bulletin 1998年第10期43卷 837-840页

作者： xu Yigang guangzhou institute of geochemistry, chinese academy of sciences, guangzhou 510640, china guangzhou institute of geochemistry Chinese Academy of Sciences Guangzhou China

Spinel peridotite xenoliths from Wangqing, NE china exhibit correlative variations in texture, temperature, geochemistry and radiogenic isotopes. This suggests that the Wangqing xenoliths may come from a mantle diapir. It is possible that the fertile and undeformed lherzolites were situated in the interior of the diapir, whereas the refractory and deformed harzburgites and clinopyroxene_poor lherzolites were within the diapiric flanks.

关键词： peridotite xenoliths texture geochemistry Wangqing.

Tree wavelet approximations with applications

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Science china Mathematics 2005年第5期48卷 680-702页

作者： xu Yuesheng & ZOU Qingsong Department of Mathematics, Syracuse University, Syracuse, NY 13244, USA institute of Mathematics, academy of Mathematics and System sciences, chinese academy of sciences, Beijing 100080, china Department of Scientific Computing and Computer Science, Zhongshan University, guangzhou 510275, china Department of Mathematics Syracuse University Syracuse USA institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China Department of Scientific Computing and Computer Science Zhongshan University Guangzhou China

We construct a tree wavelet approximation by using a constructive greedy scheme (CGS). We define a function class which contains the functions whose piecewise polynomial approximations generated by the CGS have a prescribed global convergence rate and establish embedding properties of this class. We provide sufficient conditions on a tree index set and on bi-orthogonal wavelet bases which ensure optimal order of convergence for the wavelet approximations encoded on the tree index set using the bi-orthogonal wavelet bases. We then show that if we use the tree index set associated with the partition generated by the CGS to encode a wavelet approximation, it gives optimal order of convergence.

关键词： greedy algorithms tree wavelet approximations Besov spaces.

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Acta Geologica Sinica(English Edition) 1995年第3期69卷 273-287页

作者： Wang Liankui, Zhang Shaoli, xu Wenxin, Liang Yuelong, Deng Gaoqiang, and Sha Liankunguangzhou Branch, institute of geochemistry, chinese academy of sciences, guangzhou, Guangdong Jiang M inxi guangzhou Branch Institute of Geochemistry

The traditional idea proposes that granites on the east and west coasts of the Pacific Ocean are different. According to field investigations of the geology of the western United States coupled with the authors' long-term studies on granites in South china, granites both in eastern china and in the western United States are similar.

关键词： Similarities Between Granites on the East and West Coasts of the Pacific Ocean Ruby West

Identification and analysis of shear waves recorded by three-component OBSs in northeastern South china Sea

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Progress in Natural Science:Materials International 2008年第2期18卷 181-188页

作者： Minghui Zhao ,xuelin Qiu,Shaohong Xia,Ping Wang,Kanyuan Xia,Huilong xu Key Laboratory of Marginal Sea Geology,South china Sea institute of Oceanology,chinese academy of sciences,guangzhou 510301,china Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China

Structure models associated with P-and S-wave velocities contain considerable amount of information on lithology and geophysical properties,which can be used to better understand the complexity of the deep crustal structure. However,records of converted shear waves are less due to the speciality of seismic survey at sea and the rigorous generated conditions. The study on shear waves has always been a weakness for studying the deep crustal structures of South china Sea (SCS). In this paper,eleven three-component OBSs were deployed along the Profile OBS-2001 in northeastern SCS. After the data processing of polarization and band-pass filter,converted S-wave phases were identified in the radical component records of nine OBSs. Taking the OBS7 as an example,identification and analysis of converted shear waves were presented and discussed in detail. A few phase groups,such as PwSc,PgSs,PnSc,PmS,and PwSn,were found coming from the deep crust or Moho interface by simple theoretical model calculation and ray-tracing simulation. The results not only provide the underlying basis for studies of S-wave velocity structure and Poisson’s ratio structure,but also reveal the relationship between crustal petrology and seismology,which will be of importance for making full use of S-wave information in the future.

关键词： Converted shear wave Deep crustal structure Three-component ocean bottom seismometer Northeastern South china Sea

Distribution and identification of the low-velocity layer in the northern South china Sea

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Progress in Natural Science:Materials International 2007年第5期17卷 591-600页

作者： Zhao Minghui, Qiu xuelin, xu Huilong, Shi Xiaobin, Wu Shimin , Ye Chunming and Xia Shaohong (Key Laboratory of Marginal Sea Geology, South china Sea institute of Oceanology, chinese academy of sciences, guangzhou 510301, china Earthquake Administration of Guangdong Province, guangzhou 510070, china) Key Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China Earthquake Administration of Guangdong Province Guangzhou 510070 China

The low-velocity layer (LVL), closely related with tectonic activities and dynamic settings, has always been a hot topic in the deep crustal structure studies. The deep seismic (OBS/OBH) and onshore-offshore experiments have been extensively implemented in the northern South china Sea (SCS) since the 1990s. Six seismic profiles were finished on the northern margin of SCS by domestic and international cooperations. The features of crustal structures were revealed and five velocity-inversion layers were discovered. Among them three LVLs with 3.0—3. 5 km·s-1 velocity are located in the sedimentary structure (2.0—6.0 km in depth and 2.0—4. 6 km in thickness) of the Yinggehai Basin and Pearl River Mouth Basin. They were identified by the reflective and refractive phases for their shallow depth. The other two LVLs with 5.5—6.0 km·s-1 velocity generally existed in the middle crust (7.0—18.0 km in depth) with an about 2.5—6.0 km thickness in the transitional crustal structure of the northeastern and northwestern SCS. They were detected by the refractive phase from their overlain and underlying layers. We explored the possible tectonic formation mechanisms combining with previously reported results, which provided evidence for the formation and evolution of SCS.

关键词： low-velocity layer deep crustal structure the northern South china Sea OBS/OBH and onshore-offshore seismic experiments.

Preliminary Response of Soil Fauna to Simulated N Deposition in Three Typical Subtropical Forests

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Pedosphere 2006年第5期16卷 596-601页

作者： xu Guo-Liang MO Jiang-Ming ZHOU Guo-Yi FU Sheng-Lei institute of Ecology South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 （China） Graduate School of the chinese academy of sciences Beijing 100039 （China）

A field-scale experiment arranged in a complete randomized block design with three N addition treatments including a control (no addition of N), a low N (5 g m-2 year-1), and a medium N (10 g m-2 year-1) was performed in each of the three typical forests, a pine (Pinus massoniana Lamb.) forest (PF), a pine-broadleaf mixed forest (MF) and a mature monsoon evergreen broadleaf forest (MEBF), of the Dinghushan Biosphere Reserve in subtropical china to study the response of soil fauna community to additions of N. Higher NH4+ and NO3- concentrations and a lower soil pH occurred in the medium N treatment of MEBF, whereas the NO3- concentration was the lowest in PF after the additions of N. The response of the density, group abundance and diversity index of soil fauna to addition of N varied with the forest type, and all these variables decreased with increasing N under MEBF but the trend was opposite under PF. The N treatments had no significant effects on these variables under MF. Compared with the control plots, the medium N treatment had significant negative effect on soil fauna under MEBF. The group abundance of soil fauna increased significantly with additions of higher N rates under PF. These results suggested that the response of soil fauna to N deposition varied with the forest type and N deposition rate, and soil N status is one of the important factors affecting the response of soil fauna to N deposition.

关键词： Dinghushan Biosphere Reserve N deposition soil fauna subtropical china

Regional patterns of particulate spectral absorption in the Pearl River estuary

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chinese Science Bulletin 2003年第21期48卷 2344-2351页

作者： CAO Wenxi, YANG Yuezhong, xu Xiaoqiang, HUANG Liangmin & ZHANG Jianlin LED Laboratory, South china Sea institute of Oceanology, chinese academy of sciences, guangzhou 510301, china Correspondence should be addressed to Cao Wenxi (e-mail: wxcao@ ***) LED Laboratory South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China

Spectral absorption coefficients of the total particulate, ap(l ), nonalgal particulate, ad(l ), and phyto-plankton pigment, aph(l ), in the Pearl River estuary and its vicinity waters were determined using the quantitative filter technique. The particulate absorption ap(443) ranged from 0.04 to 1.82 m-1, with the corresponding aph(443) ranging from 0.016 to 0.484 m-1. Two typical spectral patterns are found for the total particulate absorption. For the first typi-cal spectral pattern, the total particulate absorption spectra are similar to that of nonalgal particulate, with values of absorption coefficient decreasing with wavelength. In con-trast, for the second spectral pattern the spectral absorptions by total particulate are very similar to that of phytoplankton pigment. The spectral dependency of absorption by nonalgal particulate follows an exponential increase toward short wavelengths, with an average slope of 0.012±0.002 nm-1. The nonalgal absorption and the fraction of the nonalgal particulate absorption to the total particulate absorption exhibit a distinct trend of decreasing with salinity of the sur-face water. Phytoplankton pigment absorption exhibits a clear trend of increasing nonlinearly with chlorophyll a con-centration. The relationships between the phytoplankton pigment absorption and chlorophyll a concentration can be described by power law, with the determination coefficient r2 of 0.82. But only weak relationships between ap(l ) and chlorophyll a concentration are observed, with the determination coefficient r2 of 0.42. The relatively large scatter around ap(443) versus chl-a relationship would be attributed to the effects of loading of the nonalgal particulate absorption. Our analysis indicated that such relationships similar to that for Case Ⅰ waters can be applicable to optically complex Case Ⅱ waters if the effects caused by nonalgal are corrected. The chlorophyll-specific absorption coefficients of phytoplankton pigment are not constant, it

关键词：光谱吸收系数浮游植物色素叶绿素珍珠河

The Formation of Yanshanian Granitic Magma in Dabie Mountains:Dehydration or Aquifer Melting-with Tiantangzhai and Jiuzihe Granites as Examples

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Continental Dynamics 2001年第2期6卷 39-47页

作者： WANG Qiang, ZHAO Zhenhua, QIU Jiaxiang, WANG Renjing, xu Jifeng guangzhou institute of geochemistry, chinese academy of sciences, guangzhou P.R.C 510640 china University of Geosciences, Wuhan, P.R.C 430074 guangzhou institute of geochemistry Chinese Academy of Sciences Guangzhou P.R.C 510640 china University of Geosciences Wuhan P.R.C 430074

There are large-areas of late Yanshanian granites in the Dabie Orogen, but the formation mode of the relevant granitic magma is still under discussion. Taking the typical Yanshanian granites in the North Dabie Block - The TG and JG as examples, the Writers endeavor to discuss contain aspects of the formation mode of the granitic magma by studying the characteristics of the chemical compositions of biotite and amphibole of the granites and petrological features of enclaves in the intrusions, in the light of recent results of experimental petrology on dehydration melting and aquifer melting. It is suggested that: (1) Some biotites in the Tiantangzhai and the JGs and their enclaves were residual minerals; (2) Some of the amphiboles could be new-born minerals, and others, residual ones. (3) the banded bodies in granites were residuals of anatexis. (4) The TG and JG were formed by aquifer melting, and the South Dabie Block could be the important source region of water.

关键词： petrogenesis of granite dehydration melting aquifer melting enclaves characteristics aquifer fluid the Dabie Orogen

A REAL-TIME MATHEMATICAL MODEL FOR TWO DIMENSIONAL TIDAL FLOW AND WATER QUALITY

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Journal of Hydrodynamics 1991年第3期3卷 35-40页

作者： Zeng Fan-tang xu Zhen-cheng Chen Xian-cheng, South china institute for Environmental sciences, NEPA, Yuancun, guangzhou 510655, P.R.china South china Inst for Environmental Sciences Guargzhou China

A real-time mathematical model for two dimensional tidal flow and water quality is presented in this paper. The control-volume-based-finite-difference method and the 'power interpolation distribution' advocated by Patankar [4] have been employed, and new boundary condition for tidal flow is recommended. The model is un- conditionally stable and convergent, and able to deal with irregular estuarine topography and movable boundary problems. Practical application of the model is illustrated by an example for the Swatou Bay. A fair agreement be- tween the values measured and computed demonstrates the validity of the model developed.

关键词： A REAL-TIME MATHEMATICAL MODEL FOR TWO DIMENSIONAL TIDAL FLOW AND WATER QUALITY