A technique for conducting seismic refraction experiments on the ocean bed using bottom shots     

R. E. Kirk  K. Robertson  R. B. Whitmarsh  P. R. Miles 《Marine Geophysical Researches》1991,13(2):153-160

A technique has been devised for firing arrays of bottom shots on the ocean bed in depths upto 4000 m or more. Ten kilogram explosive charges are dropped from the surface while the shooting ship is navigated acoustically. They are detonated at preset times by an electronic timer which initiates an electrical detonator, detonating cord and cast PETN/TNT explosive. Ranges to ocean bottom seismographs, and the shot instants, can be calculated from the arrival-time differences of the direct and surface-reflected water waves. The accuracy, which is dependent on water-depth and range, was better than 22 m in range and 14 msec in shot instant for our experiments.  相似文献   

Numerical modeling of nonlinear water waves over heterogeneous porous beds   总被引：1，自引：0，他引：1  

Eric C. Cruz  Qin Chen   《Ocean Engineering》2007,34(8-9):1303-1321

The transformation of nonlinear water waves over porous beds is studied by applying a numerical model based on Chen's [2006. Fully nonlinear Boussinesq-type equations for waves and currents over porous beds. Journal of Engineering Mechanics, 132:2, 220–230] Boussinesq-type equations for highly nonlinear waves on permeable beds. The numerical model uses a high-order time-marching solution and fourth-order finite-difference schemes for discretization of first-order spatial derivatives to obtain a computational accuracy consistent with the model equations. By forcing the wave celerity and spatial porous-damping rate of the linearized model to match the exact linear theory for horizontal porous bed over a prescribed range of relative depths, the values of the model parameters are optimally determined. Numerical simulations of the damped wave propagation over finite-thickness porous layer demonstrate the accuracy of both the numerical model and governing equations, which have been shown by prior theoretical analyses to be accurate for both nominal and thick porous layers. These simulations also elucidate on the significance of the higher-order porous-damping terms and the influence of the hydraulic parameters. Application of the model to the simulation of the wave field around a laboratory-scale submerged porous mound provides a measure of its capability, as well as useful insight into the scaling of the porous-resistance coefficients. For application to heterogeneous porous beds, the assumption of weak spatial variation of the porous resistance is examined using truncated forms of the governing equations. The results indicate that the complete set of Boussinesq-type equations is applicable to porous beds of nonhomogeneous makeup.  相似文献   

思林水电站通航建筑物高边坡稳定分析和评价     

徐力群  沈振中  俞凯加  吕军 《岩土力学》2008,29(Z1):42-46

应用ANSYS结构分析软件,模拟了思林水电站通航建筑物高边坡的地形、地质条件以及开挖的过程,建立边坡开挖的有限元计算分析模型,分析边坡在自然状态、分级开挖以及锚杆支护加固等工况下的应力、变形及其整体稳定性.定义单元的局部安全系数,得到了边坡开挖加固后稳定安全系数的分布.根据计算成果,指出现设计加固措施可以保证边坡稳定,无需增加其他工程措施.  相似文献   

Impact of Montmorillonite and Calcite on Release and Adsorption of Cyanobacterial Fatty Acids at Ambient Temperature   总被引：1，自引：0，他引：1  

刘邓  杨小芬  王红梅  李继红  苏念 《中国地质大学学报(英文版)》2008,19(5):526-533

Minerals might act as important sorbents of sedimentary organic matter and reduce biodegradation, which favors the formation of hydrocarbon source rocks in the earth's history. Since most organic matter is degraded during the sinking process, at ambient temperature, it is important to investigate the adsorption capacity of different minerals during this process, to assess the organic loss from primary productivity to sedimentary organic matter. In this study, montmorillonite and calcite have been selected to study the impact of different minerals on the release, adsorption, and deposition of cyanobacterial (Synechococcus elonpata) fatty acids (FAs) at ambient temperature. Gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) have been utilized to detect the variation in fatty acids. Primary results suggest that minerals have a different impact on dissolved organic matter. Montmorillonite can specifically enhance the release of fatty acids from cyanobacterial cells by lowering the pH values of the solution. The adsorption of the dissolved organic matter by montmorillonite will also be enhanced under a lower pH value. Conjunction of fatty acids with montmorillonite to form a complex will favor the sinking and preservation of these organics. Selective adsorption is observed among fatty acids with different carbon numbers. In contrast, calcite does not show any impact on the release and adsorption of organic matter even though it is reportedly capable of acting as a catalyst during the transformation of organic matter at high temperature. The primary data bridge a link between primary productivity and sedimentary organic matter, suggesting the relative importance of claystones in the formation of hydrocarbon source rocks in the earth's history.  相似文献   

碎屑岩与火山岩混积岩系层序地层学研究初探——以准噶尔盆地西北缘佳木河组为例   总被引：1，自引：0，他引：1  

祝彦贺  颜耀敏  王英民  耳闯  李羊羊 《现代地质》2008,22(2):255-263

准噶尔盆地西北缘前陆冲断带是剖析西准噶尔地区盆山耦合关系、沉积体系发育的关键地段。该区二叠系佳木河组为火山岩、火山碎屑岩、碎屑岩组成的混积地层。火山岩与碎屑岩组成的地层单元有广义上的成因联系,因为它们都属于史密斯地层,并均具有旋回特征。针对不同的岩性区:碎屑岩岩性区、火山岩与碎屑岩共存区、纯火山岩区,找出由于构造火山活动、相对湖平面变化等因素形成的可作为层序界面的不整合面。碎屑岩岩性区不整合面在地震剖面上主要表现为削蚀、底超、双向下超、顶超、下切谷等;共存区为同时发育火山岩与碎屑岩的削蚀带,不整合面类型较复杂;纯火山岩区表现为相对湖平面下降形成的削蚀不整合面。故可以通过地震、钻测井资料识别各类不整合面,并依据火山喷发方式、火山旋回、沉积旋回,按照不同对比原则进行经典层序地层学划分。  相似文献   

黄河内蒙古段上覆水、悬浮物和底泥重金属特征及生态风险研究   总被引：24，自引：12，他引：12  

赵锁志  刘丽萍  王喜宽  李世宝  朱锁  郑萍  张青  张宝  蒙奎文 《现代地质》2008,22(2):304-312

系统地采集黄河内蒙古段上覆水、悬浮物和底泥样品,分析其中重金属元素的含量。采用地质累积指数法和潜在生态危害系数法,研究了黄河干流内蒙古段的上覆水、悬浮物和底泥的重金属沿程分布特征、污染程度和生态风险。分析结果显示:除了As元素,悬浮物中重金属元素含量总体上高于底泥中的含量。地质累积指数法评价结果表明:悬浮物和底泥属于无污染—中度污染,悬浮物总体上比底泥污染严重;潜在生态危害系数法评价结果表明:底泥和悬浮物中重金属的生态危害总体上属轻微状态;因此,生态风险指数法和地质累积指数评价结果基本一致。  相似文献   

新疆北部石炭纪地层、岩相古地理与烃源岩   总被引：8，自引：1，他引：7  

吴晓智  齐雪峰  唐勇  卫延召  侯连华 《现代地质》2008,22(4)

依据近几年新疆区域地质调查结果,结合新疆油田与吐哈油田最新勘探成果,通过区域构造背景和沉积充填演化特征推断石炭系沉积建造样式,理顺了新疆北疆地区石炭纪地层层序,目的是推断石炭纪烃源岩发育层段与主力生烃区范围。下石炭统有效烃源岩分布较广,主要发育于北疆西准噶尔达尔布特山前、博格达山前、准噶尔东部陆东—五彩湾地区早石炭世被动陆缘海相和海陆过渡相沉积盆地;上石炭统有效烃源岩分布相对局限,主要发育于东准噶尔克拉美丽山前石钱滩区、布尔津—吉木乃区及库普—三塘湖区海陆过渡相沉积盆地内。石炭系油气成藏严格遵循"源控论",有效生烃区决定其有效成藏范围,所伴随发育的火山岩体决定其富集程度。优选西准噶尔、东准噶尔、库普—三塘湖区、博格达山前区、布尔津—吉木乃区石炭系烃源岩发育区及其相邻构造带,作为今后石炭系油气勘探战略选区的重要领域和区带。  相似文献   

火山沉积岩及其矿床研究中伽马测井曲线解释的误区     

冯宝华 《物探与化探》2008,32(2):171-174

根据酸性凝灰岩和酸性火山事件粘土岩的自然伽马测井曲线,对当前流传的"沉积岩层的放射性强度(或放射性核素的含量)随泥质含量的增加而增高"的概念和用自然伽马值及经验公式求泥质含量提出质凝。酸性凝灰岩的自然伽马曲线有高异常响应,若解释为泥岩显然是误解,故将沉积岩伽马曲线高异常一律解释为泥岩是片面的。各类火山事件粘土岩的伽马值相差悬殊,但其泥质含量几乎相等,用它们的伽马值计算泥质含量误差甚大。最后对铝土矿层的伽马曲线稍加解释,指出核测井应用的远景。  相似文献   

贵州中东部剩余重力异常与区域矿产分布关系   总被引：1，自引：0，他引：1  

王亮  张应文  龙超林  晏承志  张家德  王毅  海宇清 《物探与化探》2008,32(2):116-121,125

重点研究1:20万剩余重力异常,结合航磁、物性、地质等资料,初步圈定区内隐伏、半隐伏岩浆岩体,对研究与重力异常、岩体分布关系密切的矿产的时间、空间分布及其成因,有一定参考价值和指示意义。  相似文献   

化学地层学研究中的若干注意事项     

刘疆  白志强 《物探与化探》2008,32(4):345-349

化学地层学因其交叉学科特点和研究对象的复杂性使得研究过程中任何一个环节的不足都将造成测试出现偏差,成果的可信度也将出现问题。高昂的成本也要求研究者把有限的资源集中到正确的目标上。近20年研究历程却恰恰将此类性质的问题陆续暴露了出来。如采样阶段获取原生性状考虑不充分或依据不足、测试阶段缺乏校验、数据分析阶段挖潜和综合利用有待完善以及化学岩、碎屑岩和生物岩各自的基础性和针对性研究有待提高等。有些问题带有相当程度的普遍性,有些甚至是严重的核心技术问题。笔者结合最新相关研究成果对上述问题进行了逐一分析和系统修正。  相似文献