额尔古纳—满洲里地区中生代火山岩与铀成矿地质条件研究     

张振强 《国土资源》2000,(4)

与我国相毗邻的蒙古、俄罗斯超大型火山岩型铀矿床的发现促进了我国对额尔古纳—满洲里地区中生代火山岩铀成矿条件的研究。在野外调研、样品分析及资料综合整理基础上，本文从火山岩的火山喷发旋回与演化、岩性组合、岩石铀含量、岩石化学及火山岩形成环境方面分析了该区中生代火山岩的铀成矿地质条件，认为该区与国内外产铀火山岩特征相似，成矿地质条件优越，是我国超大型火山岩型铀矿床极具远景的地区。  相似文献   

热采条件下储集岩的软化及其防治     

李旭 《地球科学与环境学报》1999,(Z1)

许多储集岩经蒸汽和热水处理后，可产生明显的软化作用。这种软化作用主要是由于白云石、高岭石和石英的部分破坏和生成蒙脱石。在这种情况下，软化作用是相当大的，直至足以引起储集岩中支撑裂隙的显著愈合，因而，能导致钻井产能的显著减少。已经发现把一些物质（ＲＡ） 添加到热液中，不仅能够防止岩石软化，而且能使岩石硬化。这一效果来源于岩石中原始粘土矿物的改变和新生矿物相的重结晶和重新取向  相似文献   

Implementation of the European Water Framework Directive: Natural variability associated with the CARLIT method on the rocky shores of the Ligurian Sea (Italy)     

Valentina Asnaghi  Mariachiara Chiantore  Rosa‐Maria Bertolotto  Valeriano Parravicini  Riccardo Cattaneo‐Vietti  Federico Gaino  Paolo Moretto  Davide Privitera  Luisa Mangialajo 《Marine Ecology》2009,30(4):505-513

The Water Framework Directive (WFD) 2000/60/EC, adopted by the European Community in 2000 with the goal of maintaining and improving the aquatic environments, requires that member states achieve and maintain a good ecological status of all water bodies by 2015. In the marine context, the ecological status has to be quantified applying indexes based on appropriate key biological elements, which allow the categorization of water bodies into five Ecological Status (ES) classes. The CARLIT index is a cartographic monitoring tool enabling the Ecological Quality Ratio (EQR) to be calculated using macroalgae in coastal hard bottoms as a key biological element; at present it is being applied in Spain, France and Italy. To detect actual changes of water quality and, consequently, rely on the application of indexes for the assessment of the ecological status in the marine environment, it is necessary to evaluate their sensitivity to natural variability at different temporal and spatial scales. In this study we present a first quantification of natural (spatial and temporal) variability of EQR‐CARLIT quality assessment in 2006 and 2007 along the Ligurian coast (North‐Western Mediterranean, Italy). The EQR‐CARLIT values recorded along the Ligurian coastline show that natural variability of EQR‐CARLIT is low and that it does not affect the attribution of a given stretch of coast to a particular ES class, in agreement with the major human pressures acting in the area (urbanization, river load, sea‐farming). A small‐scale variability was detected, strengthening the use of cartography of the whole rocky shore, whenever possible, or, alternatively, the assessment of the ecological status for long stretches of coast, to encompass the small‐scale variability due to local factors.  相似文献   

广西合浦海草床生态系统服务功能价值评估   总被引：3，自引：0，他引：3  

韩秋影  黄小平  施平  张景平 《海洋通报(英文版)》2008,10(1):87-96

海草床生态系统是生物多样性丰富和生产力高的近岸海洋生态系统，本文以广西合浦海草床为例，结合实地调查、已有的研究成果和当地统计资料，综合运用生态经济学、资源经济学等基本理论和方法，对该地区海草生态系统的服务功能进行了价值评估。结果表明2005年该地区海草生态系统的服务功能价值为6．29×105元／a·ha，其中间接利用价值最大，为4．47×105元／a·ha，占总经济价值的70．97％；其次为非利用价值，为1．54x105元／a·ha，占总经济价值的24．52％；最少的是直接利用价值为2．84×104元／a·ha，仅占总经济价值的4．51％。  相似文献   

曹妃甸浅滩表层砂体插桩深度研究   总被引：1，自引：1，他引：0  

陶常飞  吴建政  亓发庆  张子鹏 《海岸工程》2008,27(4):54-59

曾妃甸浅滩原为古滦河三角洲，三角洲废弃后，海底表层沉积物在波浪潮流的簸选及自重应力作用下，沉积物颗粒粗化，粒度单一，且堆积紧密，工程强度较高。平台在该海医插桩时往往难以贯穿该层，其实际插桩深度较预定深度存在较大偏差。本文对此类砂体的形成机制、插桩过程中土体的压实作用对砂体强度的影响进行了分析，在对砂体力学参数做出适当调整后，运用太沙基地基极限荷载公式进行计算，得到了与实际情况较为一致的结果。  相似文献   

The effect of heterogeneous stress and strain on metamorphic fluid flow,Mary Kathleen,Australia, and a model for large-scale fluid circulation *     

N. H. S. OLIVER  R. K. VALENTA  V. J. WALL 《Journal of Metamorphic Geology》1990,8(3):311-331

In the Proterozoic Mary Kathleen Fold Belt, northern Australia, infiltration of large volumes of externally derived fluid occurred synchronously with regional amphibolite-facies metamorphism and deformation. This paper develops a model of structurally controlled fluid migration by comparing the distribution of fossil fluid pathways with the inferred stress and strain patterns during the deformation. Intense fluid flow was localized within strong, relatively brittle meta-intrusive bodies, and in discrete, veined, brecciated and altered zones around their margins. In metasediments folded in a ductile manner outside these areas, fluid infiltration was negligible. The direct correlation between structural styles and the magnitude of veining and metasomatism suggests control of permeability enhancement, and hence fluid flow, by deformation. Finite difference modelling of a strong body in a weaker matrix has been used to evaluate the variation of stresses during the deformation, from which it is clear that stress and strain heterogeneities have systematically influenced the development and maintenance of metamorphic fluid pathways. Particular regions in which mean stress may be significantly lower than the average lithostatic pressures include the ‘strain shadow’zones adjacent to the strong bodies, other dilatant zones around the bodies, and the bodies themselves. This geometry is favourable not only for localized brittle deformation under amphilobite facies conditions, but also for focused fluid flow in the low mean stress regions, as evidenced by the abundance of veins. Fluid access through these metamorphic aquifers occurred during tensile failure episodes, with particularly large dilations and decimetre-scale veining in areas of strain incompatibility. It appears likely that fluid circulated many times through the Fold Belt, with flow concentrated in the metamorphic aquifers. A model is developed that explains both the structurally focused fluid flow and the postulated multi-pass recirculation by dilatancy pumping, the ‘pump engines’comprising the low mean stress zones.  相似文献   

Hydrogeology of limited aquifer in a granitic terrain     

V. S. Singh  V. Krishnan  M. R. K. Sarma  C. P. Gupta  R. L. Dhar 《Environmental Geology》1999,37(1-2):90-95

 Detailed hydrogeological studies in a granitic micro-watershed have been carried out to determine the extent, behavior, and characteristics of the aquifer. The study includes analysis of lithologs, drill time log, pumping tests, and slug tests. Realistic field conditions have been taken into account for characterizing the aquifer system. Slug tests were carried out to estimate aquifer parameters at the wells which could not sustain pumping. Received: 20 November 1997 · Accepted: 23 February 1998  相似文献   

Heterogenous zircons from Mesozoic igneous rocks in the North China Craton and their tectonic implications     

MIAO Laicheng  FAN Weiming  ZHANG Fuqin  LIU Dunyi 《东北亚地学研究》2009,(3):122-133

Based on a synthesis of zircon inheritance from Mesozoic igneous rocks in the eastern portion of the North China Craton （NCC） , it is proposed that inherited zircons with Neoproterozoie ages identified from these rocks are of a heterogenous derivation from the Yangtze/South China block, rather than from the NCC itself. The mechanism that introduces these zircons incorporated into the NCC is likely by tectonic underplating during the Triassic continental subduction of the Yangtze block beneath the NCC. Tectonic addition of abundant crustal materials represented by the heterogenous zircons into the NCC, probably along Moho or weak interfaces within the NCC＇s crust, led to the crustal thickening in the NCC. These heterogenous materials, either as （partial） source rocks or as contaminants of the magmas generated during an extension environment following the crustal thickening, were reworked and therefore have significant contribution to petrogenesis of the Mesozoic igneous rocks. The crustal thickening resulted from the tectonic underplating, as indicated by the distribution extent of the heterogenous zircons, is spatially similar to that of the lithospheric thinning, with both mainly occurring in the eastern segment of the NCC. This is probably suggestive of an intrinsic relation between the thickening and thinning events during the Mesozoic evolution of the NCC.  相似文献   

浅层物探技术在近海灾害地质与工程地质调查中的应用     

王舒畋 《海洋地质译丛》2008,(1):6-12

随着海洋资源的开发与滨岸工程的建设,越来越多地遇到海洋地质灾害的影响与危害。为了避免并降低海洋地质灾害的影响程度,应开展海洋灾害地质与工程地质调查。二十多年来的实践经验表明,若采用以高分辨率地震为主,配合浅地层剖面、旁侧声纳、测深及磁力测量等综合浅层物探技术,对于了解海洋地质灾害因素与海底浅部工程地质特性等方面都能取得良好的效果,这是一种既经济又较快速地提供成果资料的好方法。  相似文献   

鄂尔多斯盆地塔巴庙地区上古生界源岩热演化特征     

戴世立  杨智  李弘  杨姣 《海洋地质译丛》2009,(1):15-20

鄂尔多斯盆地北部主力气源岩太原组、山西组煤系地层热成熟史的研究对本区天然气充注过程和有利目标区预测具有重要的参考价值。在对研究区烃源岩评价和一维、二维地质建模研究的基础上。利用BasinMod盆地模拟软件对单井以及研究区内二维剖面、平面进行了煤系烃源岩热演化史模拟研究。研究结果表明：（1）该区在中三叠世进入生烃门限，中侏罗世以后，烃源岩持续埋深，早白垩世末期至最大埋深（4000m左右），绝大多数的天然气都在这一阶段生成，早白垩世末构造抬升以后只有少量天然气生成；（2）研究区上古生界太原组和山西组煤系源岩最大累积生烃强度可达到2200×10^8m^3／km^2，对现今天然气的分布具有较强的控制作用。  相似文献