南京新济洲湿地生态恢复研究

以新济洲湿地为例,研究了长江洲滩湿地生态恢复的内涵,提出了生态恢复工程方案。新济洲湿地位于长江下游南京市江宁区段,由于自然因素和人为因素的影响,该湿地结构和功能发生了明显的变化。通过对新济洲湿地的野外研究,分析了退化湿地生态系统的特征,从湿地生境、生物、结构与功能方面阐述了生态恢复的总体构想,研究了湿地恢复的工程手段与可持续利用模式。新济洲湿地生境恢复包括栖息地、基底、水体和土壤的恢复;湿地生物恢复途径有提高植被覆盖率、控制外来物种和保护野生动植物;湿地结构与功能恢复内容包括生态序列重建,生态系统、湿地景观与生物多样性恢复。湿地恢复的工程手段有景观建设、功能区建设、生态定位站、血吸虫防治、植被移植、防护林和河道整治等;湿地可持续利用模式包括桑基鱼塘、生态农业与生态旅游。     

山区公路隧道建设对地下水环境扰动评价研究

由于长大隧道建设期间具有显著地集水廊道效应，施工过程中地下水不断向隧道轴线汇集，进而诱发一系列的水文 地质灾害，给施工人员和隧址区周边的生态环境带来不可估量的损失。为此，在构建山区公路隧道建设对地下水环境扰动 评价体系的基础上，考虑到群决策不同个体实践认知水平的差异，把基于决策人员偏好信息的区间数层次分析模型用于山 区公路隧道建设对地下水的环境影响评价领域，并与模糊综合评判法进行有机结合，对西藏米拉山特长隧道建设对地下水 环境影响进行评价，结果表明，米拉山特长公路隧道建设对地下水的扰动程度属于一般水平。依据评价结果，采取了相 应的工程措施，实现了隧道建设与隧址区环境保护的协调统一，可为类似地区隧道建设的地下水环评工作提供有益的 参考。     

京津唐地区地壳结构与强震的发生──Ⅱ．S波速度结构

利用１９８６－１９９３年发生在京津唐地区的２５１６个地震的２１９２７个Ｓ波到时进行层析成像，得出：（１）公元１０００年以来研究区强震震中在下地壳的投影大多分布在低速块体内或低速块体与高速块体相交地带偏低速块体的一侧；（２）唐山地震震源下方的物质，波速比Ｖｐ／Ｖｓ呈现高值，推测呈部分熔融状态，有热物质流从莫霍界面的下方沿通向震源下方的断裂入侵的迹象。（３）黄骅坳陷中心区的上地壳呈现低Ｖｐ／Ｖｓ值，推测那里为水－汽转变的地热系，这与在该地区所测量的高热流值一致。冀中坳陷区的高Ｖｐ／Ｖｓ值反映出其地下物质可能呈部分熔融状态。     

The Generation and Compaction of Partially Molten Rock

The equations governing the movement of the melt and the matrixof a partially molten material are obtained from the conservationof mass, momentum, and energy using expressions from the theoryof mixtures. The equations define a length scale _c called thecompaction length, which depends only on the material propertiesof the melt and matrix. A number of simple solutions to theequations show that, if the porosity is initially constant,matrix compaction only occurs within a distance _c of an impermeableboundary. Elsewhere the gravitational forces are supported bythe viscous stresses resulting from the movement of melt, andno compaction occurs. The velocity necessary to prevent compactionis known as the minimum fluidization velocity. In all casesthe compaction rate is controlled by the properties of the matrix.These results can only be applied to geological problems ifthe values of the permeability, bulk and shear viscosity ofthe matrix can be estimated. All three depend on the microscopicgeometry of the melt, which is in turn controlled by the dihedralangle. The likely equilibrium network provides some guidancein estimating the order of magnitude of these constants, butis no substitute for good measurements, which are yet to becarried out. Partial melting by release of pressure at constantentropy is then examined as a means of produced melt withinthe earth. The principal results of geological interest are that a meanmantle temperature of 1350?C is capable of producing the oceaniccrustal thickness by partial melting. Local hot jets with temperaturesof 1550?C can produce aseismic ridges with crustal thicknessesof about 20 km on ridge axes, and can generate enough melt toproduce the Hawaiian Ridge. Higher mantle temperatures in theArchaean can produce komatiites if these are the result of modestamounts of melting at depths of greater than 100 km, and notshallow melting of most of the rock. The compaction rate ofthe partially molten rock is likely to be rapid, and melt-saturatedporosities in excess of perhaps 3 per cent are unlikely to persistanywhere over geological times. The movement of melt througha matrix does not transport major and trace elements with themean velocity of the melt, but with a slower velocity whosemagnitude depends on the distribution coefficient. This effectis particularly important when the melt fraction is small, andmay both explain some geochemical observations and provide ameans of investigating the compaction process within the earth.     

The Generation of Kimberlites, Lamproites, and their Source Rocks

Measurements of rare earth element (REE) concentrations in SouthAfrican kimberlites and in the Argyle lamproite from WesternAustralia constrain the composition of the source rocks fromwhich these melts originate. To account for the concentrationsof Tm, Yb, and Lu in these magmas, their sources must firsthave been strongly depleted by 20% melting in the garnet stabilityfield, and then enriched by a metasomatic melt rich in lightREE and other incompatible elements. The calculated source compositionsclosely resemble those of coarse, low-temperature, depletedperidotite nodules that are the commonest nodules in kimberlites.Rarer nodule types have undergone either more or less depletionthan have the source regions of kimberlites and lamproites.The REE composition of the metasomatic melt calculated fromthe diopsides and garnets in the sheared nodules, from the diopsidemegacrysts, and from majorite garnet inclusions in diamonds,is in excellent agreement with that expected for a melt producedby melting 0.5% of the source region of ocean ridge basalts.The initial depletion event requires the extraction of 20% meltfrom a region in which garnet and chrome-spinel were stable.The melt distribution obtained from inversion of komatiite compositionssatisfies both these conditions. Kimberlite source rocks areshallower than the layer from which fertile nodules originate.Such nodules must therefore be transported by entrainment ofthe lower boundary of the layer that becomes unstable. Thisproposal can account for their strong fabric.     

慢速—超慢速扩张西南印度洋中脊研究进展

西南印度洋中脊具有慢速—超慢速扩张速率和斜向扩张的特征,是全球洋中脊系统研究的热点之一,也是研究海底构造环境、热液活动、地幔深部过程及其动力学机制的重要区域。在前人工作的基础上较为详细地介绍了西南印度洋中脊的研究历史、地形划分、扩张速率及其构造特征,归纳了西南印度洋中脊热液活动及岩石地球化学特征,探讨了超慢速扩张洋脊和超镁铁质岩系热液系统的特殊性,并认为超慢速扩张洋脊广泛暴露的地幔岩及其蛇纹石化作用、超镁铁质岩系热液系统以及热液硫化物成矿作用是西南印度洋中脊今后研究的重要内容。     

2008年度大气科学领域项目评审与研究成果分析

12008年项目申请、送审与资助情况2008年地球科学五处共受理各类项目706项。其中:面上项目356项,青年科学基金210项,地区科学基金22项,上述三类项目共588项;“天气与气候系统变化过程与机制”优先发展领域重点项目23项(其中大气学科22项),“全球变化及其区域响应”优先发展领域     

Gravity studies of the Rockall and Exmouth Plateaux using SEASAT altimetry

Abstract SEASAT altimetric measurements are used to determine the gravity anomalies across two passive continental margins: the western margin of the Rockall Plateau, UK, and the Exmouth Plateau off north-west Australia. The small gravity anomalies observed over the starved western margin of the Rockall Plateau require the existence of a major density contrast within the crust, as well as the Moho, and show that the elastic thickness is less than 5 km at the time of rifting. The gravity anomaly over the Exmouth Plateau is compared with the gravity anomaly calculated from the sediment loading of a thin elastic plate, taking account of the variation in crustal thickness. This comparison shows that the Exmouth Plateau also has a small effective elastic thickness of 5 km, even for loads emplaced between 60 and 120 Myr after rifting. Elastic thicknesses of about 5 km have also been reported for other sedimentary basins, and are to be expected if the rheological properties of the crust and mantle depend on the ratio of the present temperature to the melting temperature. Flexural effects are therefore likely to be of minor importance in sedimentary basins.     

油气田开发中后期的储层三步建模法——以赵凹油田为例

三步建模法强调建立等时地层对比格架是储层建模的关键,即首先借助地震、测井和钻井岩心等资料,利用高分辨率层序地层学理论建立精细的等时地层对比格架,继而在格架内以不同层次的旋回层序建立沉积微相模型,从而在沉积微相的约束下建立储层物性模型.三步建模法应用于赵凹油田的结果显示,所建立的模型较好地反映了储层地下特征,经验证效果较好.