龙门山构造带南段向西南延伸的遥感影像证据及地震地质意义

在系统总结活动断裂遥感影像解译标志的基础上,利用Landsat ETM、Google Earth及ASTER GDEM等影像资料,结合前人研究成果,重点分析了龙门山构造带南段主要活动断裂的空间展布及几何学与运动学特征。研究结果表明,龙门山构造带在向南延伸过程中发生了明显的断裂分散现象,整个断裂带逐渐展宽,主要包括5条断裂带且其中包含多条次级断裂,至最南端被北西向鲜水河左旋走滑断裂带阻挡。其中活动性较为明显的断裂自西向东主要有4条:泸定断裂、天全断裂、芦山断裂和大邑-名山断裂,前两者是北川-映秀断裂的南延分支,而后两者是安县-灌县断裂的南延部分。由于龙门山构造带南段的构造变形被分解至多条次级断裂上,导致单条断裂错断地表的活动迹象明显变弱,因此单条断裂的潜在发震频率和强度也将相应变小,但潜在震源区会更为分散。结合已有的地震地质资料认为,未来应注意泸定和雅安2个地区的地壳稳定性及未来强震危险性问题。      

苏锡常地区主要地质灾害及防治措施

自20世纪80年代初以来,苏锡常地区由于超量开采深层地下水,相继出现了地面沉降、地裂缝等地质灾害,已造成了大量的经济损失,成为影响本地区经济社会发展的重要制约因素。本文在分析苏锡常地区地质环境条件的基础上,总结出本地区地质灾害主要类型、分布特征以及形成条件等,并对人类活动可能遭受地质灾害的危险性进行分析,进而提出地质灾害的防治措施。     

西藏纳当地区永珠组构造变形特征

西藏纳当地区石炭系永珠组主要为浅变质的砂板岩组合,断层和褶皱非常发育的特征。依据岩石和构造特征可以把区内永珠组分成上、中、下三段。永珠组形成于拉张的被动大陆边缘向裂谷转换的次深海环境,并于中晚二叠世至晚三叠世期间经历了三个构造演化阶段。     

南岭地区前震旦纪基底特征及其对铀成矿的贡献

南岭地区是我国很重要的铀矿产地,该区是否存在前震旦纪基底一直的是研究的热点。本在大量野外调查和室内分析的基础上,厘定了南岭地区前震旦纪基底的存在,详细论述了前震旦纪基底地层——寻乌岩组的地球化学特征,分析了寻乌岩组成岩环境及其对铀成矿的贡献,为南岭地区富大铀矿的寻找提供依据。     

巴东北部地区地表水的环境化学特征及水质评价

对巴东北部地区地表水的环境化学特征进行了初步研究,并且定量分析了此区域的水质.研究表明,该地区地表水属于典型的碳酸盐地表水,元素含量都处于低水平,没有明显的重金属污染,测定7个水样中的元素含量的平均值可以作为巴东北部地区地表水的背景值.     

Hydrochemical and isotopic characteristics of groundwater in the Souss Upstream Basin, southwestern Morocco

Heterogeneous shallow Plio-Quaternary formations of the Souss Plain represent the most important aquifer in southern High Atlas Mountains in Morocco. The present work was conducted in the Souss Upstream Basin to identify the chemical characteristics and the origin of groundwater in an aquifer under semi-arid climate. Isotopic and hydrochemical compositions combined with geological and hydrogeological data were used for this purpose. The total dissolved solids vary from 239 to 997 mg l⁻¹, and the following groundwater types are recognized: Ca²⁺–Mg²⁺–HCO₃⁻, Ca²⁺–Mg²⁺–SO₄²⁻ and Ca²⁺–Mg²⁺–Cl⁻. The groundwater is saturated and slightly supersaturated with respect to carbonate minerals and undersaturated with respect to evaporite minerals, which means that the groundwater composition is largely controlled by the dissolution of carbonate rocks known in the basin. The isotopic contents of groundwaters ranged from −8‰ to −5.2‰ for δ¹⁸O, from −52‰ to −34‰ for δD, and from 0 to 5.5 TU for tritium. The hydrogen (δD) and oxygen (δ¹⁸O) isotope signatures reveal a significant infiltration before evaporation takes place, indicating a major recharge directly from fractures in the crystalline and limestone formations of Atlas Mountains (above 800 m a.s.l.) and infiltration of surface water in the alluvial cones at the border of the Atlas basins. The very low tritium values suggest that the groundwater recharge follows a long flow path and a mixing between old and modern water is shown. However, a slight evaporation effect is noted in the southern part of the basin close to the Anti-Atlas Mountains.     

三峡库区泥灰质岩石斜坡带构造对岩溶地质灾害的控制机理

三峡库区三叠系巴东组(T26)泥灰质岩石岩溶是移民迁建中发现的重大工程地质问题。泥灰质岩石中的构造非常复杂，包括老构造、新构造和表生构造，它们共同控制了岩溶作用。老构造中，褶皱和断裂带等局部构造控制着岩溶的重要部位和重要层位，节理和层理等小构造使岩溶普遍存在。新构造时期地表隆升和河流切割使岩体卸荷松动，岩溶通道扩宽。表生岩溶构造加密了岩溶通道，使岩溶作用增强。三峡库区泥灰质岩石斜坡带地质灾害形成的机理遵循着构造控制下岩溶发育的规律性，致使岩溶地质灾害具有范围广、规模大和结构复杂的特点。岩溶地质灾害的形式包括地面不均匀沉降、地裂缝、滑坡、崩塌、泥石流和地面塌陷。     

鲁中南岱崮地貌的成因及演化——以抱犊崮为例解析

鲁中南抱犊崮地区,山体陡峭挺拔,风景秀丽,以有鲁南小泰山之称的抱犊崮为代表,山体顶部主要由古生代寒武纪九龙群张夏组灰岩组成,其下分布由长清群馒头组砂岩、砂质页岩、泥质灰岩、薄层灰岩及朱砂洞组灰岩、泥质灰岩等。“崮”的成因主要是古生代寒武纪灰岩经受了强烈的地壳切割和抬升运动,并遭受长期的侵蚀、溶蚀、重力崩塌和风化剥蚀等多重地质作用而形成抱犊崮所具有的岱崮地貌,作为地质遗迹和地质地貌景观,具有重要的地学研究价值,也是潜力巨大的旅游资源。     

Morphotectonic evaluation of the Delhi region in northern India,and its significance in environmental management

This paper deals with the morphotectonic evaluation of the Delhi region in northern India to understand its impact on land use and urban development. To accommodate heavy urbanization and population rise (being the capital of India), the area has undergone tremendous environmental degradation resulting from a mismatch between adopted land use and morphotectonic considerations. The geomorphic and drainage signatures of the region have evolved out of interaction of varied geological parameters including neotectonic activities. We have evaluated the changes in the drainage pattern of the Yamuna River in the Delhi region to underline its significance in geomorphic evolution and subsequent land use and/or land suitability. The Yamuna River has shown variations both in channel position and geometry over the last two centuries. The observed migration pattern of the river (shifting of confluences, position and disposition of palaeochannels, etc.,) cannot be attributed to normal river phenomenon and appears to have been effected by neotectonic changes. In addition, some case studies are discussed to underline the significance of geomorphic factors in urban development.