Heavy metals in stream sediments from copper and gold mining areas in southern Brazil     

Maria Heloisa D. Pestana  Milton L.L. Formoso  Elba C. Teixeir 《Journal of Geochemical Exploration》1997,58(2-3)

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New paleomagnetic results from the Aegean extensional province     

Haubold  Herbert  Scholger  Robert  Kondopoulou  Despina  Mauritsch  Hermann J. 《Geologie en Mijnbouw》1997,76(1-2):45-55

Various Oligocene formations from NE Greece (ignimbrites from the Medousa area, rhyolites from Zagradenia, granodiorites from Elatia) show discordant paleomagnetic signatures, in each case indicating small cw (clockwise) rotation and also inclination flattening. Marls from Pithion were partly remagnetized in a present-day field. Samples that contain ancient magnetization components also indicate small cw rotation and inclination flattening. However, the magnetization of andesites from Peplos reflects a considerably larger rotation, likely owing to local tectonics. In the context of previous work in the area, these results are used to propose a subdivision of NE Greece into four structural zones of distinctive rotational behaviour (from east to west): sites in zone 1, east of the Kavala-Xanthi-Komotini fault (KXK), show various cw and ccw (counterclockwise) rotation angles owing to complex kinematics resulting from the interaction of the KXK and the north-Anatolian fault zone. However, zone 2, between the KXK and the Strymon valley, is structurally homogeneous ( 10° cw rotation). The paleomagnetic signature of the Vertiskos massif (zone 3) implies a larger (> 30°) cw rotation, whereas sites in the Vardar basin (zone 4) contain a paleomagnetic signature similar to that of zone 2. This suggests a motion of the Vertiscos massif, a meta-ophiolitic nappe, relative to underlying strata. Indeed, zones 2 and 4 may be parts of the same structural unit which underlies this nappe.  相似文献   

Impact cratering - a review,with special reference to the economic importance of impact structures and the Southern African impact crater record     

W. U. Reimold 《Earth, Moon, and Planets》1995,70(1-3):21-45

Only since several decades has impact cratering been recognized as an important surface process on all planetary bodies in the Solar System. However, as the process has not yet been effectively introduced into geological curricula, it is necessary to inform a wider public about its importance for (i) planetary formation and (ii) evolution, (iii) the understanding of this process as a geological process, (iv) the terrestrial impact crater record and its limitations, and (v) the recognition criteria for terrestrial impact structures, as well as (vi) the need of improvement of the impact cratering record in the light of the potential danger of an impact catastrophe on this planet. It is, particularly for developing countries, of interest to examine the economic and educational-environmental potential of impact structures. That it is possible to carry out an effective, low-budget geological investigation of impact structures within a Second World environment is demonstrated by the discussion of the progress that has been made in recent years with regard to the Southern African impact crater record. Several recommendations on how to improve, on the one hand, the terrestrial impact crater record and, on the other, their general working situation by activation of workers in Developing Countries are discussed.  相似文献   

Cross-formational hydrocarbon fluid flows in the Tertiary deltaic system of the Beaufort–Mackenzie Basin     

Maowen Li  Yongqiang Xiong  Lloyd R. Snowdon  Dale Issler 《Journal of Geochemical Exploration》2006,89(1-3):214

Molecular and isotopic compositions of crude oils in the Beaufort–Mackenzie Basin confirm three genetic end-member oil groups and suggest extensive cross-formational hydrocarbon fluid flows in the Tertiary deltaic system. Inter- and intra-fractional variations in the geochemistry of the Tertiary-reservoired oils indicate that the oil source/maturity signatures were substantially masked by biomarkers that were picked up along migration pathways. Thus, many of the previously recognized “immature non-marine oils” are in fact thermally mature, probably derived from unpenetrated deeper marine source rocks. Although the effective source rock volumes have not been evaluated and their exact stratigraphic levels remain unknown, the relative timing of oil generation versus trap formation, rather than poor source quality, may be the cause of under-filled traps in the offshore area.  相似文献   

Analysis of the effect of geology, soil properties, and land use on groundwater quality using multivariate statistical and GIS methods     

Jin-Soo Lee Kyung-Seok Ko Tong-Kwon Kim Jae Gon Kim Seong-Hyun Cho In-Suk Oh 《中国地球化学学报》2006,25(B08):152-152

The regional survey of groundwater used as a small water supply system was performed to know the effect of geology, soil properties and land use on groundwater quality at Nonsan City, Korea. A total of 126 groundwater samples were collected and analyzed at the study area. The multivariate statistical methods, principal components analysis and discriminant analysis, and GIS technique were used for the quantitative interpretation of groundwater quality. The study area is mainly composed of Precambrian gneiss, Jurassic granite, and Cretaceous volcanics, and metasedimentary rocks of the Ogcheon zone. The land use was grouped as paddy, upland, grassland, resident, point source, industrial area, and water system. The soil properties were classified as 4 major groups, Entisols, Alfisols, Inceptisols, and Ultisols, by the degree of development, and reclassified as 11 subgroups. The modified and simplified geologic map, soil map, and land use map were made by using ARCGIS soft-ware. The area of geology, soil property, and land use affecting the groundwater quality for each well were also calculated by ARCGIS soft-ware to acquire the quantitative parameters for multivariate statistical analysis. The monitoring results of groundwater in the study area showed that 13%-21% of the groundwater samples exceeded the portable water guideline and the main causes were turbidity, bacteria, arsenic and nitrate-N. The spatial distribution of each component showed the close relationship between groundwater quality and geology reflecting the topography, land use.  相似文献   

Engineering geological studies and tunnel support design at Sulakyurt dam site, Turkey   总被引：2，自引：0，他引：2  

H. Basarir 《Engineering Geology》2006,86(4):225-237

This paper presents the results of engineering geological investigations and tunnel support design studies, carried out at the Sulakyurt dam site, northeast of Ankara, Turkey. The Sulakyurt dam will be used for flow control and water storage for irrigation projects. Studies were carried out both in the field and the laboratory. Field studies include engineering geological mapping, intensive discontinuity surveying, core drilling and sampling for laboratory testing. The diversion tunnel will be driven in rock mass, consisting of granite and diorite. Empirical, analytical and numerical methods were combined for safe tunnel design. Rock mass rating (RMR), Rock mass quality (Q) and Geological strength index (GSI) systems were used for empirical rock mass quality determination, site characterization and support design. The convergence–confinement method was used as analytical method and software called Phase², a 2D finite element program, was utilized as numerical method. According to the results acquired from the empirical, analytical and numerical methods, tunnel stability problems were expected in both granite and diorite rock masses. The support system, suggested by empirical methods, was applied and the performance of suggested support system was evaluated by means of numerical modelling. It was concluded that the suggested support systems were adequate, since after applying the suggested support system to granite and diorite, tunnel deformation and the yielded elements around the tunnel decreased significantly. Thus, it is suggested that for more reliable support design empirical, numerical and analytical methods should be combined.  相似文献   

中国能源安全与南海开发   总被引：2，自引：0，他引：2  

于文金  朱大奎 《世界地理研究》2006,15(4):11-16

二十一世纪是海洋经济时代。随着我国经济的发展,能源问题日益突出。由于我国陆上石油资源日益枯竭,海上石油开发成为我国能源的战略重点。南海陆架新生代地层厚约2000～3000m。第三纪沉积有海相、陆相及海陆交互相,具有良好的生油和储油岩系。南海扼海上要冲-马六甲海峡,南海航线是我国能源的海上生命线,具有不可替代的战略地位。我国南海资源和海域主权遭受到极大的侵犯。发展深海油气的勘探和开发技术,开发我国的南海深水石油资源,维护我国海域主权已经刻不容缓。优先进行南海石油开发是破解我国石油能源困局的必选战略。  相似文献   

A north-south section across the Queyras Schistes lustrés (Piedmont zone, Western Alps): Syn-collision refolding of a subduction wedge     

Pierre Tricart  Stephane Schwartz 《Eclogae Geologicae Helvetiae》2006,99(3):429-442

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遥感技术在煤炭地质中的应用现状及前景   总被引：6，自引：0，他引：6  

张文若  康高峰王永 《中国煤田地质》2006,18(2):5-8,59

介绍了遥感技术在煤炭资源调查和评价、煤矿区地质灾害调查和评估、生态环境及污染调查评价和监测以及煤矿三维可视化仿真规划系统建设方面的应用研究现状及所取得的主要成果，并结合遥感技术的发展方向，展望了其在煤炭地质中的应用前景。  相似文献   

皖中泥质岩工程性质探讨     

兰中平  许军才  董业才 《华东地质学院学报》2006,29(1):62-65

历来对半胶结泥质岩风化等级划分都带有许多主观性,从而影响提承载力,有的规范要求可不对半胶结岩石进行风化程度划分,但有时要对这些岩石进行工程地质细分,从而准确确定各分层的承载力与摩阻力。统计了合肥、六安、淮南、安庆地区等大量实践资料,用标准贯入击数、重型圆锥触探实验击数等原位测试手段来划分泥质岩风化等级,并对泥质岩的承载力与摩阻力等工程地质性质做出了评价。  相似文献