~(40)Ar/~(39)Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai, East 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 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 220 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 213.1±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age o     

Cascaded Evolution of Mantle Plumes and Metallogenesis of Core- and Mantle-derived Elements

Mineral deposits are unevenly distributed in the Earth's crust, which is closely related to the formation and evolution of the Earth. In the early history of the Earth, controlled by the gravitational contraction and thermal expansion, lighter elements, such as radioactive, halogen-family, rare and rare earth elements and alkali metals, migrated upwards; whereas heavier elements, such as iron-family and platinum-family elements, base metals and noble metals, had a tendency of sinking to the Earth's core, so that the elements iron, nickel, gold and silver are mainly concentrated in the Earth's core. However, during the formation of the stratified structure of the Earth, the existence of temperature, pressure and viscosity differences inside and outside the Earth resulted in vertical material movement manifested mainly by cascaded evolution of mantle plumes in the Earth. The stratifications and vertical movement of the Earth were interdependent and constituted the motive force of the mantle-core movement.     

浅析湘南地区锰矿矿源物质来源

简述湘南地区表生氧化锰矿矿源层的分布及岩性特征，讨论矿源层与构造及岩相古地理的关系。     

论桩基施工中流砂现象处理

地下水流动对土体产生渗透力；当渗透力大于土体的抗剪强度，土体破坏，也就是当施工造成地下水水力坡度超过砂层的临界水力坡度即产生流砂现象．运用水文地质工程地质学方面的原理其处理方法有两类：—是莫尔一库仑法：即c法和φ法；二是临界水力坡度法(Ic法)．     

WZY-1型钻参仪的研究与应用

分析了目前钻参仪未能普遍推广应用的原因。介绍了WZY－1型钻参仪的总体构成、测试参数、性能特点及其分别与钻机和水泵的一体化设计。     

差异性风化岩石作为桩基持力层设计应注意的若干问题

基岩中存在软弱夹层为岩石的差异性风化的主要特征。在不均匀性地基土上选用该类地层作为钻孔灌注桩持力层时，它的存在将对桩长、单桩承载力、桩体沉降等带来不同程度的影响。以黄石电厂为例，指出在选用差异性风化岩石作为桩基持力层时应注意的若干问题。     

二维有限元网格的自适应剖分及程序实现

有限单元法在计算岩土力学领域已得到广泛应用。在有限元的分析计算中，前处理工作即准备计算数据耗时费力。如何简化前处理工作、实现网络自动生成对于推广有限元分析至关重要。作者在综合考虑多种算法原理的基础上，对非规则几何图形、复连通域的二维模型提出了一套新的自适应剖分算法。该算法可以同时生成三角形单元和四边形单元，还能对单元形状进行规则性调整。给出了详细的实施步骤，并编写了相应的应用程序，应用程序同时提供了对单元节点进行优化排序的功能。实际应用表明，能够高效快速地给出良好的剖分网格。     

昆明南市区地下热水环境质量评价

昆明市地热田的开发利用已有20多年历史，部分地段长期过量开采诱发的环境地质问题日趋突出。本文用TOPSIS法和综合指数法对昆明市南市区近l0年来地下热水水质演变过程及现状作分析评价，研究结果表明昆明市地下热水已遭受到不同程度的污染，并且有恶化的趋势。     

镇安场变形体特征及稳定性评价

镇安场变形体位于长江左岸的重庆市涪陵区镇安场，是我国地质灾害多发地之一，主要表现为崩塌、滑坡、泥石流等地质灾害。该变形体变形的主要影响因素除地形地貌、地层岩性、物质结构外，还有瀑雨、洪水、地震、植被破坏等外在因素。通过野外勘查，运用探槽、浅井、钻探等工程控制，已查明该变形体已发生过局部变形，尚未形成大范围的变形和滑移，处于潜在滑移变形阶段。在三峡库区水位上升后，特别是在水库水位降低和地震作用下，变形体可能失稳而向下滑动。通过对变形体的稳定性的评价，认为该区沿库岸应采用以支挡工程为主、排水为辅的防治方案。     

内蒙古东乌珠穆沁旗沙麦地区中-新生代伸展构造特征研究

介绍了伸展构造概念与研究现状，沙麦地区中—新生代伸展构造基本特征与形成机制。认为区内中—新生代盆地是地壳呈北西西—南东东向伸展的结果，地壳的伸展演化并不连续，呈现幕式伸展的特点。