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库车盆地西北缘下第三系碳、氧同位素特征及成岩环境 总被引：3，自引：0，他引：3
库车盆地西北缘及柯坪地区下第三系碳酸盐岩稳定同位素分析结果显示氧同位素组成在相对较小的范围内变化，而碳同位素组成变化很大。沉积学研究表明塔拉克组和小库孜拜组海相地层主要为潮坪、萨布哈和渴湖相沉积，在成岩过程中或成岩期后，沉积物不同程度地受到了淡水作用的影响。所分析的样品大部分形成于大气淡水成岩环境，富集１２Ｃ，δ１３Ｃ为正值的样品一般形成于海水成岩环境。稳定同位素分析是研究成岩作用的有效手段之一。 相似文献
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昌黎海岸风成沙丘的形态与沉积构造特征及其成因初探 总被引：18，自引：1，他引：18
本文论述了昌黎海岸风成沙丘的分布与形成特征、层理构造及其沙丘表面沙波发育情况．并对其成因进行了探讨．沙丘迎风坡表面普遍发育有风成沙纹，层理构造非常发育，有低角度交错层理、大型板状交错层理。海岸沙丘沉积物主要来自滦河．滦河入海泥沙在偏风浪的作用下向北搬运并堆积在海滩上．强劲的向岸风使海滩沙向陆搬运建造成海岸沙丘。目前．沙丘仍在活动之中。 相似文献
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本文用离散影响函数核(discrete kernel)方法分析了在承压含水层非稳定流的井径经验井损问题。并得出如下结论:井的容量可以减小井损量,且井容量对抽水初期是有影响的;增大井径可以克服井的无效性;大井径经验井损的比降深与抽水量呈非线性关系;在大井径中的无量纲时间降深曲线(其井损分量遵循Jacob方程)不是唯一的,它与抽水量有关。 相似文献
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Sustainable management of coastal and coral reef environments requires regular collection of accurate information on recognized ecosystem health indicators. Satellite image data and derived maps of water column and substrate biophysical properties provide an opportunity to develop baseline mapping and monitoring programs for coastal and coral reef ecosystem health indicators. A significant challenge for satellite image data in coastal and coral reef water bodies is the mixture of both clear and turbid waters. A new approach is presented in this paper to enable production of water quality and substrate cover type maps, linked to a field based coastal ecosystem health indicator monitoring program, for use in turbid to clear coastal and coral reef waters. An optimized optical domain method was applied to map selected water quality (Secchi depth, Kd PAR, tripton, CDOM) and substrate cover type (seagrass, algae, sand) parameters. The approach is demonstrated using commercially available Landsat 7 Enhanced Thematic Mapper image data over a coastal embayment exhibiting the range of substrate cover types and water quality conditions commonly found in sub-tropical and tropical coastal environments. Spatially extensive and quantitative maps of selected water quality and substrate cover parameters were produced for the study site. These map products were refined by interactions with management agencies to suit the information requirements of their monitoring and management programs. 相似文献
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The exploration and production of North Sea oil and gas reserves has resulted in the accumulation of large quantities of drill cuttings on the seabed surrounding drill sites. This complex mixture of man-made and natural substances contains higher concentrations of certain metals (Ba, Cr, Cu, Ni, Pb, and Zn) and hydrocarbons than are observed in background sediments. With decommissioning of older platforms underway, an evaluation of the environmental interactions and chemical fate of the drill cuttings accumulations is required.This review concentrates on contaminants within drill cutting accumulations in the Northern and Central North Sea (56 degrees N-62 degrees N). Present literature reviewed reveals that hydrocarbons within the cuttings piles remain relatively unchanged with time. A considerable proportion of the associated contaminants are likely to remain within the cuttings pile unless they are disturbed which will then increase exchanges of porewater and solids back to the seabed surface resulting in pathways of exposure for organisms. 相似文献