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Some basic concepts and problems on the petrogenesis of intra-plate ocean island basalts

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Chinese Science Bulletin 2009年第22期54卷 4148-4160页

作者： NIU Yaoling1,2,3.1 Department of Earth Sciences, Durham university, Durham DH1 3.E, UK 2 School of Earth Sciences and Resources, china university of Geosciences, {3. 100083. china 3.School of Earth and Space Sciences, peking university, beijing 100871, china Department of Earth Sciences Durham University Durham DH1 3LE UK School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China School of Earth and Space Sciences Peking University Beijing 100871 China

Basaltic magmatism that builds intra-plate ocean islands is often considered to be genetically associated with "hotspots" or "mantle plumes". While there have been many discussions on why ocean island basalts (OIB) are geochemically highly enriched as an integral part of the mantle plume hypothesis, our current understanding on the origin of OIB source material remains unsatisfactory, and some prevailing ideas need revision. One of the most popular views states that OIB source material is recycled oceanic crust (ROC). Among many problems with the ROC model, the ocean crust is simply too depleted (e.g., [La/Sm]PM > 1) OIB. Another popular view states that the enriched component of OIB comes from recycled continental crust (RCC, i.e.; terrigenous sediments). While both CC and OIB are enriched in many incompatible elements (e.g., both have [La/Sm]PM >>1), the CC has characteristic enrichment in Pb and deletion in Nb, Ta, P and Ti. Such signature is too strong to be eliminated such that CC is unsuitable as source material for OIB. Plate tectonics and mantle circulation permit the presence of ROC and RCC materials in mantle source regions of basalts, but they must be volumetrically insignificant in contributing to basalt magmatism. The observation that OIB are not only enriched in incompatible elements, but also enriched in the progressively more incompatible elements indicates that the enriched component of OIB is of magmatic origin and most likely associated with low-degree melt metasomatism. H2O and CO2 rich incipient melt may form in the seismic low velocity zone (LVZ). This melt will rise because of buoyancy and concentrate into a melt rich layer atop the LVZ to metasomatize the growing lithosphere, forming the metasomatic vein lithologies. Erupted OIB melts may have three components: (1) fertile OIB source material from depth that is dominant, (2) the melt layer, and (3. assimilation of the metasomatic

关键词：岩石成因论海洋 OIB 矿物学

Northernmost paleo-tethyan oceanic basin in Tibet:Geo-chronological evidence from ^(40)Ar/^(3.)Ar age dating of Dur'ngoi ophiolite

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Chinese Science Bulletin 2001年第14期46卷 1203-1205页

作者： CHEN Liang, SUN Yong, PEI Xianzhi, GAO Ming, FENG Tao, ZHANG Zhongqing & CHEN Wen1. Laboratory of Continental Dynamics, Northwest university, Xi’an 710069, china 2. Department of geology, Northwest university, Xi’an, 710069, china 3. Institute of geology, Chinese Academy of Geological Sciences, beijing, 10003., china Laboratory of Continental Dynamics Northwest University Xi’an China Department of geology Northwest University Xi’an China Institute of geology Chinese Academy of Geological Sciences Beijing China

Whole rock 40Ar/3.Ar age dating has been conducted on a basalt sample from Dur’ngoi ophiolite, Qinghai Province, which was reported to be the northernmost pa-leo-tethyan oceanic basin in Tibet. A high temperature pla-teau age (3.5.3.7.9 Ma) with an isochorn age (3.6.6±7.1 Ma) has been obtained, representing the eruption time of oceanic crust Considering related geological settings, the new age provides constraints on the northernmost pa-leo-tethyan suture zone in Tibet and the tectonic evolution of Paleo-tethys in Northeast Tibet and adjacent areas.

关键词： Dur’ngoi ophlolite 40Ar -3.Ar age Paleo-tethys.

Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural Science:Materials International 2005年第10期15卷 46-52页

作者： WANG Shaowu (Department of Atmospheric Science, School of Physics, peking university, beijing 100871, china) Department of Atmospheric Science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in china at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in china as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. Studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

Generalized Chow Forms and Reduction of Semi-Stable Varieties

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Acta Mathematica Sinica,English Series 2000年第2期16卷 219-228页

作者： Qingchun Tian Department of Mathematics,peking university,beijing {3.,P.R.china Department of Mathematics Peking University Beijing 100871 P. R. China

In this note,by using the method of ***[1],we obtain the local version of a theorem of BGS[2]which links Faltings heights of projective varieties with the Philippon heights for the corresponding generalized Chow *** the stable reduction theorem of ***[1],we prove that Chow semistabilities and generalized Chow semistabilities are the same.

关键词： Deligne Pairing Faltings Height Chow forms

Direct CP violation in hadronic B decays

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Science china(Physics,Mechanics & Astronomy) 2006年第3期49卷 357-366页

作者： HONG Bihai1,2 & Lü Caidian3.1. Department of Physics, Lishui university, Lishui 3.3.00,china 2. Department of Physics, Shanghai Jiaotong university, Shanghai 20003.,{3. 3. Institute of High Energy Physics, beijing 100049,china Department of Physics Lishui University Lishui 323000 China Department of Physics Shanghai Jiaotong University Shanghai 200030 China Institute of High Energy Physics Beijing 100049 China

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on kT factorization, using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.

关键词： CP violation hadronic B decay factorization.

Diagenesis and Porosity of the Cambrian-Ordovician Carbonate Shoal Fades at Yangjiaping, Shimen, Hunan

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Acta Geologica Sinica(English Edition) 2000年第1期74卷 29-45,116-117页

作者： ZHANG Xiulian, WANG Yinghua and CHEN Xiaolong Department of geology, peking university, beijing 100871 peking Univ Dept Geol Beijing 100871 Peoples R China

Upper Cambrian-Lower Ordovician shoal-facies carbonate rocks are well developed in the Yangjiap-ing section, Shimen, Hunan, and their types are also highly varied. There are both monomictic shoal-facies rocks (e.g. sparite oolitic limestone and sparite calcarenite) and polymictic shoal-facies rocks (e.g. grainstone, whose grain types include sand- and pebble-sized fragments, bioclasts, oolites, algal mats etc.). What is different is that the Upper Cambrian shoal-facies rocks have been mostly strongly dolomitized into shoal-facies dolomite with various residual textures. This paper presents an in-depth study of various kinds of diagenesis and pore space evolution occurring in this section and suggests that the diagenetic sequences of shoal-facies rocks in the study area is dominantly of retrogressive type.

关键词： rock types dolomitization dissolution diagenetic sequence

The Construction of Numerical Scheme forHyperbolic Equation and Exact Considerationof Numerical Diffusion and Dispersion

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Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 156-162页

作者： Qingdong CAI(State Key Laboratory for Turbulence Research, peking university, beijing 100871, china) State Key Laboratory for Turbulence Research Peking University Beijing 100871 China

A new technique in the formulation of numerical scheme for hyperbolicequation is developed. It is different from the classical FD and FE methods. We begin withthe algebraic equations with some undefined parameters, and get the difference equationthrough Taylor-series expansion. When the parameters in the partial difference equationare defined, the equation is what the scheme will simulate. The numerical example ofthe viscous Burgers equation shows the validity of the scheme. This method deals withthe numerical viscosity and dispersion exactly, giving a preliminary explanation to someproblems that the CFD face now.

关键词： modified equation Taylor expansion consistency truncation error

Steady States of Some Models for Van derWaals Fluids

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Communications in Nonlinear Science and Numerical Simulation 1998年第3期3卷 163-167页

作者： Shaoqiang TANG(Department of Mechanics and Engineering Science, peking university, beijing 100871,china) Department of Mechanics and Engineering Science Peking University Beijing 100871 China

We study the steady states of some models for van der Waals fluid. Inparticular, for a mass viscosity model, we show that there is no "cavitation’ wave. Wealso consider the closed orbits, heterocliaic orbits, and the... 详细信息

关键词： steady state phase transition mixed-type problem

china's energy, environment and policy perspective

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Journal of Environmental Sciences 2000年第3期12卷 270-274页

作者： ZHANG Shi\|qiu (Center for Environmental Sciences, peking university, beijing 100871, china) Center for Environmental Sciences Peking University Beijing 100871 China

This paper discusses the specific features of the energy in china, and addresses those key challenges in china is that the co\|exist of (1) higher total energy production and lower per capita level; (2) lower per capita energy resources level with unrational energy consumption structure; (3. lower energy utilization efficiency and higher energy conservation potential; and (4) unequal distribution of energy resources. It reviews the key environmental problems related to the feature of energy production and consumption. Based on the analysis, the author furthers addresses the policy and actions needed.

关键词： energy energy production energy consumption environment policy