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921.
922.
1999~2001·勘查地球化学·资源与环境 总被引:17,自引:4,他引:13
1999~2001年,勘查地球化学取得一系列重要进展和成果,在中国西部以资源调查和评价为主推进区域化探,在中国东部以环境调查和评价为主启动多目标区域地球化学填图,逐步形成新世纪勘查地球化学资源与环境并重的发展格局.与此相适应,提出了资源潜力地球化学评价与生态环境地球化学评价为主导的基本思路和方法. 相似文献
923.
通过新发现的古生物资料分析,确定了赣西北修水、武宁地区的武宁、三都及马坳盆地的地层时代。对3个盆地的沉积相进行了详细的划分和描述,查明其为冲积扇沉积类型;划分出22个岩相,归属于泥石流、泥流、颗粒流、水道(包括主水道和分枝水道2个次级类型)、片流、筛积和洪泛7个沉积类型。重力流沉积分布在扇根或主要沉积旋回的底部,其类型的差别与邻近物源区的岩性有关;分枝水道、片流及筛积主要分布在扇中,交错层理及砾石叠瓦状构造发育,主要呈现牵引流特征;扇缘主要为洪泛沉积夹少量决口扇成因的砂砾岩透镜体,钙结壳发育,反映了一种干旱强蒸发的古气候环境。 相似文献
924.
澳门是以博彩业而闻名的旅游城市,但它也拥有独特的地质旅游资源。如以岩洞、大石蛋为主的岩体景观和以红树林为主的海岸景观等。澳门地质旅游资源是构造、岩浆、海岸侵蚀等多种地质作用的产物,因而不仅具有观赏性,还具有科学考察意义。今后,应主要开发黑沙湾、红树林海岸及多种山地,造就山海岩林融为一体的天涯海角旅游胜地。 相似文献
925.
略阳县地质灾害发育特征及其危险性初步评价 总被引:5,自引:2,他引:3
根据野外实地调查,描述并总结了陕西省略阳县地质灾害的发育特征。依据地质灾害点目前的稳定状态和潜在危害程度,定性评价了区内各地质灾害点的危险性。并利用地质灾害的重现性,基于各地质灾害点的危险程度,综合区内的地形地貌、地质条件和人为因素、气象水文条件,对略阳县地质灾害危险性进行了分区,其结果可为当地的土地规划和防灾减灾提供依据。 相似文献
926.
泥河湾保护区地貌特征与地质灾害 总被引:4,自引:0,他引:4
根据泥河湾保护区实地调查,黄土台地、黄土沟梁和河谷地貌是发育在“泥河湾层”及其覆地层上的主要地貌类型,其形态特征和形态测量反映了该区流水地貌的现代演化特征。伴随流水地质作用与地貌演化发生的水土流失、泥石流、崩塌和地面塌陷等地质灾害危及保护区的地层剖面。笔者认为该区域地质灾害是多种致灾因素造成的,其中的主导因素是气候、植被和人为因素,通过控制植被因素可以改变目前的地质环境状况。 相似文献
927.
长江三峡库区(奉节-巴东段)移民工程遥感动态监测 总被引:2,自引:0,他引:2
在长江三峡库区移民工程中 ,我们采用 ETM+、SPOT、IKONOS等多源、多时相、多分辨率航天、航空遥感数据组合 ,监测移民工程的动态变化 ,通过对库区奉节 -巴东段移民搬迁建与安置、新开发用地分布、土地利用与土地结构变化、地质灾害及衍生地质灾害与防治、库区环境及生态平衡与改善经济结构以及移民工程遥感动态监测等 ,取得突破性进展 ,获取了一批重要成果。为三峡移民工程进一步全面、安全地实施、改进规划管理工作及库区经济可持续发展 ,提供了科学依据和决策性建议。 相似文献
928.
地质旅游资源是以地质遗迹为依托的旅游资源 ,开发地质旅游资源可以提高人们的生活质量 ,促进经济发展。必须实行“在保护中开发 ,在开发中保护”的总原则 ,实现地质旅游资源的可持续发展 相似文献
929.
In this part of our study the probabilistic seismic hazard analysis (PSHA) for Tulbagh was performed. The applied procedure is parametric and consists essentially of two steps. The first step is applicable to the area in the vicinity of Tulbagh and requires an estimation of the area-specific parameters, which, in this case, is the mean seismic activity rate, , the Gutenberg-Richter parameter, b, and the maximum regional magnitude, mmax. The second step is applicable to the Tulbagh site, and consists of parameters of distribution of amplitude of the selected ground motion parameter. The current application of the procedure provides an assessment of the PSHA in terms of peak ground acceleration (PGA) and spectral acceleration (SA). The procedure permits the combination of both historical and instrumental data. The historical part of the catalogue only contains the strongest events, whereas the complete part can be divided into several subcatalogues, each assumed complete above a specified threshold of magnitude. In the analysis, the uncertainty in the determination of the earthquake was taken into account by incorporation of the concept of `apparent magnitude'. The PSHA technique has been developed specifically for the estimation of seismic hazard at individual sites without the subjective judgement involved in the definition of seismic source zones, when the specific active faults have not been mapped or identified, and where the causes of seismicity are not well understood. The results of the hazard assessment are expressed as probabilities that specified values of PGA will be exceeded during the chosen time intervals, and similarly for the spectral accelerations. A worst case scenario sketches the possibility of a maximum PGA of 0.30g. The results of the hazard assessment can be used as input to a seismic risk assessment. 相似文献
930.
High and Aswan Dams Authority (HADA) proposed a plan aiming at constructing a rockfill dam in the Kalabsha area, about 60 km south of Aswan High Dam. The aim of this dam is to restrain the overflow of water to the Kalabsha Valley for keeping one billion cubic meters from being lost due to seepage and evaporation. The safety of dams during earthquakes is extremely important because failure of such a structure may have disastrous consequences on life and property. Therefore, different factors were considered as part of a site assessment. Five seismic source zones, close enough to the site to give rise to potentially damaging earthquake ground motions, were identified. Seven active faults that have the potential for producing significant earthquakes and that pass through or near the dam site were also identified. The earthquake loading represented by ground motions at the site was evaluated. Probabilistic seismic hazard procedures were used for assessing the earthquake loading at six individual sites using Area-and Line-Source Models (ASM & LSM). The ASM is based on current observed seismicity, whereas the LSM is based on geological slip rates. The output represents the expected acceleration amplitude with 90 percent probability of not being exceeded in exposure times of 20, 50, and 100 years. The results from the two models appear to be different, the expected ground motions from ASM were twice as high as expected from LSM. This difference is due to the load of the Aswan reservoir (Nasser Lake) triggering earthquakes on those parts of the faults that lie under the lake at Kalabsha area. The hazard at the selected sites is given by the hazard curve that is represented by the relationship between the peak ground acceleration and its annual exceedance probability. By comparing the curves for the six individual sites for the same source model, it can be concluded that the potential ground acceleration level for all the sites is almost the same. Considering the mean results from the two models, the annual exceedance probability of the expected ground acceleration from ASM is approximately ten times higher than the annual exceedance probability from LSM.Since ASM is based on current seismicity, it is more appropriate forrepresenting the actual hazard for the dam site. 相似文献