地球系统多圈层构造观的基本内涵

地球系统多圈层构造观的基本点是,把地球作为一个活的天体放在宇宙系统之中,更多地考虑地球深部壳-幔-核之间的相互作用,考虑地外天体对地球运动的作用和影响。这一构造观认为:构造运动并不仅仅是岩石圈板块之间的相互作用,而是地球系统的全球动力作用过程;陆与洋是对立统一相互转化的,单纯的大陆增生说是不正确的;地幔对流说至今未被证实,陆块是活动的,但不能大规模漂移;大陆地壳不是单纯地侧向或垂向增生,而是多旋回构造-岩浆作用叠合的产物;地球的构造不是均变式向前发展,而是非均变、非线性、旋回式向前演化的;地球表层在不同地史阶段,均有其受相应深断裂体系控制的不同的构造格局,大西洋—印度洋—太平洋式大洋盆体制,只是在中生代晚期以来才出现的。

从地槽—地台说、板块构造说到地球系统多圈层构造观

从19世纪中叶开始,大地构造理论经历了从地槽—地台说到板块构造说的发展过程。目前,板块构造说虽然仍在盛行,但一个新的大地构造理论——地球系统多圈层构造观(简称多圈层构造观)已在形成中。地槽—地台说,19世纪中叶提出,盛行于20世纪上半叶,是地质学家从理论上研究地壳构造及其演化的开始。地槽—地台说使用的方法是传统的地质学方法;研究领域是大陆地壳,褶皱带(造山带)和克拉通是其研究的核心内容。地槽—地台说大大推动了地质科学的发展,并为地球科学的进一步发展,奠定了良好的基础。板块构造说,起始于20世纪60年代。板块构造使用的方法,除地质学外,加上了地球物理学和地球化学等现代科学和技术手段;研究领域是全球大陆和海洋的岩石圈。板块构造说使大地构造学的研究范围从地球表层扩展到地球内部,从大陆扩展到海洋,极大地推动了地球科学向更高的层次发展。目前,板块构造说虽然仍在盛行,但是不足和缺陷已日益显露出来。地球系统多圈层构造观,孕育于20世纪80年代晚期,目前正在发展中。地球系统多圈层构造观使用的方法更现代化,包括地质学、地球物理学、地球化学以及一切探测地球深部和外层空间的方法、手段;研究领域,已不仅仅是地球表层的地壳或岩石圈,而是地球整体,地球各圈层的相互作用。我们相信,21世纪必将是地球系统多圈层构造观不断发展、不断完善的时代。中国及邻区中、新生代构造演化是全球研究多圈层构造的最理想的切入点之一。我们期待中国地学工作者在新一轮大地构造理论创新中发挥应有的作用。

中国大地构造研究之思考——中国地质学家的责任与担当

19世纪中叶到20世纪中叶盛行的地槽-地台学说,起源于西方学者对大西洋半球的欧洲和北美东部地质的研究。20世纪中叶提出的板块构造学说,虽然起源于对现代海洋的地质、地球物理调查,但用板块学说解释大陆构造的尝试,也是从解剖北美和欧洲大西洋两岸的古生代造山带开始的。二者均缺少太平洋半球的亚洲,特别是中国及邻区的资料基础,因此,其立论基础是不全面的。这就给亚洲,特别是给中国学者提供了很大的发展空间。通过1∶500万国际亚洲地质图的编制和全球构造的对比研究,笔者发现,处于亚洲核心地带的中国及邻区不仅是亚洲也是全球显生宙地质结构和发展历史最复杂的地区。古亚洲洋构造域的乌拉尔—蒙古—兴安巨型造山带是全球规模最大、发育历史最长、地质结构最复杂的古生代造山带;中国西南部,特别是青藏高原是全球特提斯巨型造山带出露宽度最大、地质纪录保存最完整的地段;中国东部的太平洋构造域,既有亚洲东缘的巨型中生代造山带和新生代的沟弧盆体系,又有宽阔的滨太平洋陆缘活化带。这就使中国及邻区成为研究全球显生宙构造不可缺少的重要地段。我们一定要抓住中国在全球构造研究中的区位优势,以地球系统多层圈构造观为指导,用地质、地球物理、地球化学多学科结合的方法,立足实际,抓住特色,构建中国大地构造的新理论、新模型,为国际地球科学,为发展、完善现代大地构造学理论做出应有的贡献!

断裂构造研究进展对工程地质学的启示

在长期地质作用下形成的岩体和岩体结构是工程地质学研究的基本内容,它们的形成和演化主要受控于构造作用,而系统地解析岩体所经历的构造作用是认识岩体结构、抽象和概括岩体工程地质模型的突破口。因此,重视和应用现代构造地质学研究的新理论、新方法必将会对岩体工程地质学研究起着重要的指导意义。本文系统总结了与工程地质研究相关的现代构造地质学理论和思维观的研究进展,在此基础上分析了这些理论方法对工程地质工作的启示和指导意义,希望起到抛砖引玉的作用。

构造体系——关于地质构造相干组合的学说

“构造体系”是1929年李四光教授提出的概念和术语。随后的年代中,李四光以构造体系为核心,创立了地质力学,并以这种理论去解决我国资源和地质灾害的一些重大问题。构造体系把地质构造作为有相干关系的组合来认识,这与现代系统科学的看法是一致的。因此构造体系是我们应该珍视和继承的科学概念。

面向系统能力培养的计算机专业实践教学模式

计算机系统能力培养是目前国内外计算机教育的新动向。系统能力的培养依赖于计算机专业理论与实践教学的有效联动,传统计算机实践教学体系存在实验目标离散、实验内容割裂、实验规模不够、实验平台分离的问题,结合系统能力培养的系统观、构造观、工程观等特征,以设计与实现完整的计算机软硬件系统为顶层目标,重构了面向计算机系统能力培养的一体化实践教学模式,并给出了相应实践教学组织保障体系。

试论"盆""山"的耦合和脱耦及其运动学

"盆""山"耦合和脱耦基于中国大陆是一个经多期碰撞-拼合形成的复合大陆、因而盆地演化与造山作用息息相关而提出,其核心是盆地研究的活动论构造观,包括用造山带地层学的理论和方法研究建造的序列和用造山带古地理学的理论和方法正确进行古构造-古地理的重建,并采用地质构造的力学分析与历史分析相结合的方法和盆地动力学分析的方法。以造山作用为主线,在给予时间约束后,从4个方面(挤压与拉张空间上互为依存、走滑断裂的转换作用、深部过程的制约和构造逸脱)研究了"盆""山"的耦合特征及其运动学。文中以中国大陆中—新生代的构造演化为例分析了"盆""山"脱耦的运动学,提出认识东、西两部侏罗纪以来的分异是理解印支期"盆""山"关系解脱的关键。

Microstructure comparison of ZK60 alloy under casting,twin roll casting and hot compression

The microstructures of ZK60 alloy under conventional direct as-casting (DC),twin roll casting (TRC) and twin roll casting followed by hot compression (TRC-HC) were analyzed by optical morphology (OM),electron backscatter diffraction (EBSD) and X-ray diffraction (XRD).The deformation condition of hot compression is 350 ℃,0.1 s?1.The microstructural evolution under TRC-HC deformation followed by annealing at different temperatures and time was discussed.The results show that TRC provides more modified microstructure compared with DC.Twins are found in TRC processing;dynamic recrystallization (DRX),shear bands and twins are found in TRC-HC.A short annealing time has little effect on hardness,while during a long time annealing,it is found that low annealing temperatures increase the micro-hardness and high temperature decreases it.

Effect of N on microstructure and mechanical properties of as-cast Ti-6Al alloy

In-situ titanium matrix composites with N content of 0. 045-0. 27 wt% have been produced by a easting method. The microstructure and mechanical properties of as-cast materials have been observed and tested. The results show that when N content in Ti-6Al alloy is between 0. 045 wt% and 0. 27 wt%, the reinforcement is a compound of Ti, Al and N, and volume fraction of reinforcements increases with an increase of N content. The hardness, compressive strength and elastic modulus are all higher than that of the matrix alloy. With the increase of N content, the compressive strength, the hardness and the elastic modulus increase. Fracture surface analysis has also shown that the matrix alloy fractures in a ductile model and the composites fracture in a cleavage brittle model with characteristics of dimple and cleavage surface.

Microstructure and mechanical properties of Mg-6Al-0.3Mn-xY alloys prepared by casting and hot rolling

Mg-6Al-0.3Mn-xY(x=0,0.3,0.6 and 0.9,mass fraction,%) magnesium alloys were prepared by casting and hot rolling process.The influence of yttrium on microstructure and tensile mechanical properties of the AM60 magnesium alloy was investigated.The results reveal that with increasing the yttrium content,Al2Y precipitates form and the grain size is reduced.The ultimate strength,yield strength and elongation at room temperature are 192 MPa,62 MPa and 12.6%,respectively,for the as-cast Mg-6Al-0.3Mn-0.9Y alloy.All these properties are improved obviously by hot rolling,and the values are up to 303 MPa,255 MPa and 17.1%,respectively,for the rolled Mg-6Al-0.3Mn-0.9Y alloy.The improvement of mechanical properties is attributed to continuous dynamic recrystallization and the existence of highly thermal stable Al2Y precipitate which impedes the movement of dislocation effectively.

Features of the M7.9 Earthquake in the Russia-Mongolia-China Boundary Region

At 19:33 p.m on September 27, 2003, an earthquake with M7.9 occurred in the Russia-Mongolia-China boundary Region. It was strongly felt in the Altay region of Xinjiang. The losses caused by the earthquake was 76 million yuan (RMB). Some information about the earthquake was outlined, including basic parameters, focal mechanism, evaluation of earthquake disaster losses and so on. The satellite remote sensing information worked initial analysis for deformation of ground and failure phenomenon.

Contemporary Crustal Motion and Deformation of South America Plate

This paper presents the contemporary motion and active deformation of South America plate and relative motion of Nazca-South America plate using space geodetic data. The South America plate is moving at average 14.5 mm/a with an azimuth of 15.2° and shrinking in the west-east at 10.9 mm/a. The geodetic deformations of sites with respect to the South America plate are in quite good agreement with the estimated deformations from NNR-NUVEL1A, but the deformation of the western South America regions is very large.

Investigation of Spring Waters to Assess the Geo-ecological State of Landscape and Soil

The purpose of the investigation was to assess the opportunity to use spring waters as indicator for the load state of rural landscape ecosystems. In the periods from 2000-2003 and 2011-2012, the physical and chemical water quality of 55 freshwater springs in the German federal state of the Saarland was investigated in monthly intervals. The catchment areas of the springs represented the prevailing geological formations in the Saarland as well as the main land use types such as forest, grassland and arable land. The results show a clear correlation between the nitrate content and the share of arable land in the closer catchment area of the springs. The problem of acidification and related processes occurs mainly at the sites with acid parent rock material and accordingly substrates deficient in lime. Very low pH-values between 4 and 5 are observed and the aluminum concentration levels are consistently increased. Especially at sites with low calcium content in the geological substrate, a progressive destruction of the clay minerals can be assumed. In the extremely acidic spring waters, which showed the highest aluminum contamination during the measurement 10 years ago, the aluminum-values decreased slightly. This indicates that the clay minerals in these locations are already completely destroyed. Thus, it can be concluded that the investigation of spring waters provides information on the geo-ecological conditions in catchment areas. By means of the multi-temporal approach, changes of land use or other influences by human activities can be detected.

New Activity of the Tanlu Fault Zone in the South of Huaihe to the Nvshanhu Segment since the Late Quaternary

Taking the Huaihe to the Nvshanhu segment of the Tanlu( Tancheng-Lujiang) fault zone as the main research target to explore whether there has been new activity since the late Quaternary,and based on the interpretation of remote sensing images and repeated surface investigations,we excavated trenches at the sections where the tectonic landform is significant,identified and recorded the deformation patterns of the fault and analyzed the activity behavior. Samples of new activity and deformation were collected and oriented slices were ground based on the samples ' original state to make the micro structural analysis and demonstration. All of the above research shows very clear linear tectonic geomorphology along the fault,three trenches across the fault zone all revealed new deformation traces since late Quaternary. The latest stratum dislocated by the fault is the late Quaternary and Holocene. The main slip mode is stick slip,as represented typically by fault scarps,wedge accumulation,the faults and the filled cracks and so on. In general,it shows the characteristics of brittle high-speed deformation and belongs to the prehistoric earthquake ruins. The above understanding was confirmed partially by microscopic analysis. In addition,the similarities and differences and the possible reasons for the characteristics of the latest activities of the Tancheng-Lujiang fault zone in the north and south of the Huaihe River regions are also discussed in this paper.

Seismic Monitoring Network and Seismic Activities in Thailand

The details of seismic monitoring network and seismological work in Thailand, including some information on felt earthquakes that occurred from 2000 to August 2001, are reported here.

Advancements in three-dimensional titanium alloy mesh scaffolds fabricated by electron beam melting for biomedical devices: mechanical and biological aspects

We elucidate here the process-structure-property relationships in three-dimensional（3 D） implantable titanium alloy biomaterials processed by electron beam melting（EBM） that is based on the principle of additive manufacturing. The conventional methods for processing of biomedical devices including freeze casting and sintering are limited because of the difficulties in adaptation at the host site and difference in the micro/macrostructure, mechanical, and physical properties with the host tissue. In this regard, EBM has a unique advantage of processing patient-specific complex designs, which can be either obtained from the computed tomography（CT） scan of the defect site or through a computeraided design（CAD） program. This review introduces and summarizes the evolution and underlying reasons that have motivated 3 D printing of scaffolds for tissue regeneration.The overview comprises of two parts for obtaining ultimate functionalities. The first part focuses on obtaining the ultimate functionalities in terms of mechanical properties of 3 D titanium alloy scaffolds fabricated by EBM with different characteristics based on design, unit cell, processing parameters, scan speed, porosity, and heat treatment. The second part focuses on the advancement of enhancing biological responses of these 3 D scaffolds and the influence of surface modification on cell-material interactions. The overview concludes with a discussion on the clinical trials of these 3 D porous scaffolds illustrating their potential in meeting the current needs of the biomedical industry.

Fabrication and applications of the protein patterns

Protein has been widely used for fabricating patterned structures since it is one of the most important macromolecules in living organisms,and protein patterns possess potential applications in many fields such as medical diagnosis,tissue engineering,biosensors,and medical screening.At present,there are two fashions to fabricate protein patterns:one is grafting the protein to the microstructure which is prepared by micro-fabrication techniques;the other one is achieving the patterned protein structures directly.Here we provide an overview on current status of the fabrication techniques and the applications of the protein patterns,and then give an outlook on the development of the fabrication techniques and the prospective applications of the protein patterns in future research.

Electron backscatter diffraction investigation of duplex-phase microstructure in a forged Zr-2.5Nb alloy

Microstructural features of a duplex-phase Zr-2.5Nb alloy were investigated in detail using electron channeling contrast （ECC） imaging and electron backscatter diffraction （EBSD） technique in an emission gun scanning electron microscope （FEGSEM）. The excellent resolution provided by the FEGSEM promises the combined utilization of both techniques to be quite adequate for characterizing the duplex-phase microstructures. Results show that the microstructure of the Zr-2.5Nb alloy is composed of bulk a grains （majority） in equiaxed or plate shape and thin 13 films （minority） surrounding the bulk grains, with their average grain size and thickness measured to be 1.4 prn and 72 nm, respectively. Analyses on a-grain boundaries reveal a number of low angle boundaries, most of which belong to deformation-induced dislocation boundaries. Measurements on relative propor- tions of various Burgers boundaries suggest very weak （if any） variant selection during 13 ~ a cooling, which should be re- lated to deformation-induced higher nucleation rate of a phases. Compared to earlier attempts, more satisfactory indexing of fine β phases （down to nanoscale） is attained by the FEGSEM-based EBSD. Examples are presented to clearly reveal well-obeyed Burgers orientation relationships between adjacent α and β phases. Finally, it is deduced that continuing applica- tion of the FEGSEM-based EBSD to duplex-phase Zr alloys could help clarify controversies like the deformation priority of the two phases.

Structure and coalbed methane occurrence in tectonically deformed coals

Research on structure of tectonically deformed coals(TDC) is a key issue in coal and gas outburst prevention and coalbed methane(CBM) exploitation.This paper presents a summary on the research progress in TDC's structural-genetic classification,tectonic strain influence on coal microstructure,coal porosity system,coal chemical structure and constituents,and their relationship with the excess coalbed methane.Previous studies suggested that tectonic deformation had significant influence on coal microstructure,coal super microstructure,and even chemical macromolecular structure.The main mechanisms of coal deformation are the tectonic stress degradation and polycondensation metamorphism(dynamical metamorphism).Besides,under different deformation mechanisms,the ultra-and micro-structure and chemical constituents of TDC presented distinct characteristics.Based on these achievements,we propose one possible evolutionary trend of TDC with different deformation mechanisms,and suggest that the coal and gas outburst in the TDC,especially in the mylonitic coals,may be not only controlled by geological structure,but also influenced by the tectonic stress degradation of ductile deformation.Therefore,further study on TDC should be focused on the controlling mechanism of deformation on structure and composition of coal,generation conditions and occurrence state of excess coalbed methane from deformation mechanism of coal.

The coupling effect of slow-rate mechanical motion on the confined etching process in electrochemical mechanical micromachining

By introducing the mechanical motion into the confined etchant layer technique(CELT), we have developed a promising ultraprecision machining method, termed as electrochemical mechanical micromachining(ECMM), for producing both regular and irregular three dimensional(3 D) microstructures. It was found that there was a dramatic coupling effect between the confined etching process and the slow-rate mechanical motion because of the concentration distribution of electrogenerated etchant caused by the latter. In this article, the coupling effect was investigated systemically by comparing the etchant diffusion, etching depths and profiles in the non-confined and confined machining modes. A two-dimensional(2 D) numerical simulation model was proposed to analyze the diffusion variations during the ECMM process, which is well verified by the machining experiments. The results showed that, in the confined machining mode, both the machining resolution and the perpendicularity tolerance of side faces were improved effectively. Furthermore, the theoretical modeling and numerical simulations were proved valuable to optimize the technical parameters of the ECMM process.