三峡库区大型单斜顺层新生滑坡变形特征与失稳机理研究

以三峡库区巫山轿顶峰2号滑坡为例,结合库水位变化、地质环境条件资料,通过现场调查测绘、无人机航空摄影测量、工程地质钻探、地表及深部位移监测等方法,详细分析了该滑坡的变形特征、成因机制与发展趋势.该滑坡体积约250×104 m3,为大型单斜顺层新生岩质滑坡.滑坡前后缘高差约380 m,前缘剪出口高陡临空,位于库区蓄水位以...     

勘查隐伏金属矿的新方法

在总结目前金属矿勘查基本现状的基础上,阐明了勘查技术方法对寻找金属矿的重要作用,论述了近十年来勘酷暑隐伏矿新方法,新技术的进展     

Tidal and meteorological forcing of sediment transport in tributary mudflat channels

Field observations of flow and sediment transport in a tributary channel through intertidal mudflats indicate that suspended sediment was closely linked to advection and dispersion of a tidal salinity front. During calm weather when tidal forcing was dominant, high concentrations of suspended sediment advected up the mudflat channel in the narrow region between salty water from San Francisco Bay and much fresher runoff from the small local watershed. Salinity and suspended sediment dispersed at similar rates through each tidal inundation, such that during receding ebbs the sediment pulse had spread spatially and maximum concentrations had decreased. Net sediment transport was moderately onshore during the calm weather, as asymmetries in stratification due to tidal straining of the salinity front enhanced deposition, particularly during weaker neap tidal forcing. Sediment transport by tidal forcing was periodically altered by winter storms. During storms, strong winds from the south generated wind waves and temporarily increased suspended sediment concentrations. Increased discharge down the tributary channels due to precipitation had more lasting impact on sediment transport, supplying both buoyancy and fine sediment to the system. Net sediment transport depended on the balance between calm weather tidal forcing and perturbations by episodic storms. Net transport in the tributary channel was generally off-shore during storms and during calm weather spring tides, and on-shore during calm weather neap tides.     

基于Johnson分布体系黄土滑坡影响范围的概率预测

通过在甘肃省天水市进行大量的现场调查,收集已经发生的黄土滑坡数据并建立数据库,利用Johnson分布体系建立了多维滑坡变量模型并预测潜在滑坡发生后的堆积区滑体长度、滑坡体的面积和滑坡体的宽度。通过对比预测结果与验证组中滑坡体真实数据发现预测模型具有较好的精准度,以预测结果90%置信区间上边界作为影响范围的安全值,推导出研究区域内潜在黄土滑坡影响范围的预测公式,并以研究区域以外的同类型黄土滑坡数据加以验证发现预测公式对天水市内其他区域同类型的黄土滑坡的评估具有一定的适用性。预测公式中只有不稳定边坡高度作为自变量,这对现场快速评估不稳定黄土潜在滑坡危害、影响范围提供了极大便利。     

加权中位数法的基本理论,方法及其应用

物化探及其他地学数据常呈现非正态分布特征,例如数据中存在特异值或在研究区有几种矿化类型时,致使数据呈现出长尾巴分布。为了提高数据处理的质量和矿石储量计算的精度,本文介绍一种地质统计学方法——加权中位数法。文中讨论了方法的理论,重点研究了方法步骤,包括距离权、丛集权和综合权的计算方法,最后给出一个计算金矿床矿石储量的实例。     

Herbicides implicated as the cause of severe mangrove dieback in the Mackay region, NE Australia: consequences for marine plant habitats of the GBR World Heritage Area

Herbicides, particularly diuron, were correlated with severe and widespread dieback of the dominant mangrove, Avicennia marina (Forsk.) Vierh. var. eucalyptifolia (Val.) N.C. Duke (Avicenniaceae), its reduced canopy condition, and declines in seedling health within three neighbouring estuaries in the Mackay region of NE Australia. This unusual species-specific dieback, first observed in the early 1990s, had gotten notably worse by 2002 to affect >30 km(2) of mangroves in at least five adjacent estuaries in the region. Over the past century, agricultural production has responded well to the demands of increasing population with improvements in farm efficiency assisted by significant increases in the use of agricultural chemicals. However, with regular and episodic river flow events, these chemicals have sometimes found their way into estuarine and nearshore water and sediments where their effects on marine habitats have been largely unquantified. Investigations over the last three years in the Mackay region provide compelling evidence of diuron, and possibly other agricultural herbicides, as the most likely cause of the severe and widespread mangrove dieback. The likely consequences of such dieback included declines in coastal water quality with increased turbidity, nutrients and sediment deposition, as well as further dispersal of the toxic chemicals. The implications of such findings are immense since they describe not only the serious deterioration of protected and beneficial mangrove habitat but also the potential for significant direct and indirect effects on other highly-valued estuarine and marine habitats in the region, including seagrass beds and coral reefs of the Great Barrier Reef lagoon. This article reviews all key findings and observations to date and describes the essential correlative and causative evidence.     

从决策分析论成矿预测

成矿预测已成为地质勘探过程中一项必不可少的活动.本文从决策论的角度结合我国开展成矿预测的实际经验,对这项活动的目的、意义、理论及其在市场经济中的地位,重新加以考察,以期使其在科学的基础上获得更快的发展.