Reconstructing fluvial bar surfaces from compound cross‐strata and the interpretation of bar accretion direction in large river deposits          下载免费PDF全文

Renato P. Almeida  Bernardo T. Freitas  Bruno B. Turra  Felipe T. Figueiredo  André Marconato  Liliane Janikian 《Sedimentology》2016,63(3):609-628

The interpretation of fluvial styles from the rock record is based for a significant part on the identification of different types of fluvial bars, characterized by the geometric relationship between structures indicative of palaeocurrent and surfaces interpreted as indicative of bar form and bar accretion direction. These surfaces of bar accretion are the boundaries of flood‐related bar increment elements, which are typically less abundant in outcrops than what would be desirable, particularly in large river deposits in which each flood mobilizes large volumes of sediment, causing flood‐increment boundary surfaces to be widely spaced. Cross‐strata set boundaries, on the other hand, are abundant and indirectly reflect the process of unit bar accretion, inclined due to the combined effect of the unit bar surface inclination and the individual bedform climbing angle, in turn controlled by changes in flow structure caused by local bar‐scale morphology. This work presents a new method to deduce the geometry of unit bar surfaces from measured pairs of cross‐strata and cross‐strata set boundaries. The method can be used in the absence of abundant flood‐increment bounding surfaces; the study of real cases shows that, for both downstream and laterally accreting bars, the reconstructed planes are very similar to measured bar increment surfaces.  相似文献   

Geodynamic evolution of the Salinas de Añana diapir in the Basque-Cantabrian Basin,Western Pyrenees     

《Journal of Structural Geology》2016

The Salinas de Añana diapir is located in the Basque-Cantabrian basin part of the great evaporite basin, along with the Gulf of Mexico and the Central European basin, when the fragmentation of Pangea started. The evolution of these basins can only be achieved by understanding the control of salt in the sedimentary and tectonic evolution of these basins.Sedimentation began with clastic Buntsandstein sediments and minor Muschelkalk limestones. Subsequent Keuper evaporites are the bottom of sedimentary cover constituted by Jurassic limestones and marls, a clastic Lower Cretaceous and an alternant limestone and marl Upper Cretaceous, whose deposition has been conditioned by salt tectonics. The emplacement of salt extends from the Aptian until now, favored by the duplication of the salt thickness associated with the thrust of Sierra Cantabria, so it is an excellent example to study changes in the regime of intrusion along the time. The geodynamic evolution of the Salinas de Añana diapir was determined through the interpretation of 45 reprocessed seismic lines, along with information from three wells. Migration of the salt in this diapir, conditioned by N120E and N30E pre-Alpine basement lineations, was determined using time isopach maps of the various rock layers. Vertical evolution of the diapir was determined through the reconstruction of a north-south section at various geologic times by flattening the respective seismic horizons. A minimum of salt flow into the diapir coincides with a minimum rate of sedimentation during the Turonian. Similarly, maximum flows of salt into the diapir occurred during the Coniacian and Lower Santonian and again from the end of the Lower Miocene to the present, coinciding with maximum rates of sedimentation during these times. In the Tertiary, probably during the Oligocene, the diapir was displaced to the south by the Sierra Cantabria thrust, maintaining the contact between the evaporites of diapir and the same evaporites of the lower block. Since the Oligocene, the salts of the lower block migrated towards and into the diapir, deforming the trace of the overthrust.  相似文献   

地史上巨量蒸发岩省的成因及其地质意义          下载免费PDF全文

李江海  马丽亚  王洪浩  许丽 《地质科学》2016,(2):619-632

全球蒸发岩从震旦纪到新近纪均有发育, 其最发育时期为震旦纪-寒武纪、二叠纪-三叠纪以及侏罗纪-白垩纪, 且具有幕式分布特点.它们在一定区域(低纬区)常大规模集中发育, 跨越不同的沉积盆地类型, 面积和厚度巨大, 时代跨度较短且连续, 笔者称之为巨量蒸发岩省.本文基于全球蒸发岩层系古板块再造、沉积岩相恢复、地层柱状对比、盆地构造分析等方法, 对巨量蒸发岩省的发育、分布、成因及其地质意义进行了探讨.巨量蒸发岩省形成、分布与地史中的造山带演化、超大陆的聚合与裂解、干旱气候带(南北纬30°之间)、海平面变化等因素有着密切联系; 其主要形成于干旱环境下相对封闭、靠海水潜流补给的台地和盆地中; 所处的构造单元主要为泛大陆板块内部狭长的裂谷带、特提斯造山带的残余洋盆、海-陆过渡带、陆表海或孤立板块的台地中心.  相似文献   

FY-3微波成像仪10.6 GHz通道超分辨率图像重建          下载免费PDF全文

陈博洋  谷松岩  陈凡胜 《应用气象学报》2016,27(1):123-128

为改善风云三号 (FY-3) 微波成像仪10.6 GHz通道空间分辨率,提出利用超分辨率图像重建算法进行图像重建。分析并指出FY-3微波成像仪10.6 GHz通道具有过采样特征,具备重建得到高于瞬时视场图像的潜力;基于超分辨率图像重建理论,根据FY-3气象卫星轨道、姿态,微波成像仪性能参数以及工作模式等物理约束,建立微波成像仪的超分辨率成像模型,并推导计算出超分辨率成像模型参数;采用POCS算法重建得到10.6 GHz通道的超分辨率图像,采用目视比较分析、图像统计分析对重建图像进行质量评价:重建图像像元平均梯度提高26.5%,功率谱分量和提高5.7%,重建图像具有更高的空间分辨率;台风亮温分析应用显示了从重建图像可发现更微小的景物细节目标。采用超分辨率图像重建算法对FY-3微波成像仪10.6 GHz通道进行重建处理,结果有效且正确,可为数据用户提供更多可用的遥感数据,对微波遥感数据应用具有提升作用。  相似文献   

多尺度细节增强的遥感影像超分辨率重建     

朱红  宋伟东  谭海  王竞雪 《测绘学报》2016,45(9):1081-1088

鉴于现有超分辨率重建方法难以突显重建影像细节信息的问题,提出多尺度细节增强的遥感影像超分辨率重建模型框架。首先,通过最小二乘滤波方法将序列影像分解成包含大尺度边缘的平滑信息和包含中小型尺度的细节信息;其次,利用插值方法得到相应的高分辨率细节信息和平滑信息,构造纹理细节增强函数,提升中小型细节的增强幅度;最终,融合细节信息和平滑信息,得到初始的超分辨率重建结果,并利用局部优化模型进一步改善重建影像质量。选取同时相和多时相遥感影像作为试验数据。试验结果表明,本文重建结果与插值方法、TV方法和MAP方法相比,在客观评价指标上均有显著提高,明显改善了重建影像的纹理细节。论文提出的多尺度细节增强的超分辨率重建方法,可以使重建影像提供更多高频细节信息,具有较好鲁棒性和普适性。  相似文献   

平行轮廓线自适应插值的三维表面重构算法     

孟耀伟  孙毅中 《测绘科学》2016,41(5):121-126

针对稀疏点轮廓线在三维表面重构中存在的不够光滑、匹配易出错和难以交互等问题,提出了基于轮廓线插值的三维表面重构方法,并通过实验进行验证。文章分析了三维表面重构的形式化表达方法和准则,提出了基于虚跨距解决稀疏点轮廓线三维重构的基本思想;基于同步前进算法和虚跨距,设计了自适应等比例插值的同步前进三角面镶嵌算法;针对轮廓线插值违背三角表面重构拓扑准则的规律进行了分析,提出了相应的修正算法,保证了三角网的拓扑一致性。试验结果表明:本算法所构建的三角网表面更为光滑,各个三角面的大小更为均匀,具有更好的鲁棒性和交互性,对稀疏和稠密坐标点的轮廓线均能构建出更为理想的三维表面模型。  相似文献   

低空大比例尺地形图航测生产关键技术   总被引：3，自引：1，他引：2  

吴博义  苏国中 《测绘科学》2016,41(8):138-143,133

针对传统航空摄影测量生产工艺在生产过程中遇到的影响大比例尺测图精度的问题,该文探讨了低空航测生产大比例尺地形图的关键技术。通过选用宽角相机、低航高飞行、强化影像匹配、野外布设标志控制点、优选平差模型、精化测图操作等改进方式,以提高大比例尺航测精度;组建无人飞艇低空航测系统,对提出的技术方法予以实现;最后给出了山西境内近30个县市建成区1∶500测绘生产实践的部分验证成果。  相似文献   

时变参数灰色模型背景值重构及实现     

周万春  周强波  黄九松  刘鸿剑 《测绘科学》2016,41(6):173-178

针对时变参数灰色模型PGM(1,1)的背景值重构收敛速度及稳定性问题,该文运用积分的方法综合序列在Δt内不同变化趋势,导出背景值模型的准确表达式。实现了反映序列对新老信息偏爱程度的最优权值介于(0,1)内,且非不能越过某一阈值;给出了背景值重构模型最优解准确求取的具体算法步骤。基于MATLAB语言的实验结果表明:改进模型预测精度高,易于实现;所研究的带权灰色模型GM(1,n)背景值模型的重构及计算方法验证了PGM(1,1)模型重构及计算实现方法的有效性和实用性。  相似文献   

遥感影像超分辨率处理方法与研究进展   总被引：1，自引：1，他引：0  

陆婉芸  王继周 《测绘科学》2016,41(12):53-58,69

随着人们对影像高分辨率需求的不断增加,图像超分辨率技术已成为相关研究领域的热点之一。针对在遥感领域并非所有的超分辨率方法都可用的现状,该文按照遥感影像超分辨率处理的流程,将超分辨率问题分为退化模型、配准、重建和精度评定4大模块。对于其中每一模块的理论、常用方法与研究进展进行了较全面的综述及比较分析。最后对这一领域的未来发展进行思考和展望。  相似文献   

Fourier-based multi-scale representation and progressive transmission of cartographic curves on the internet   总被引：1，自引：0，他引：1  

Pengcheng Liu  Weibo Liu  Tinghua Ai 《制图学和地理信息科学》2016,43(5):454-468

ABSTRACT

Automatic generation of multi-scale representations from the same spatial data source has been the research focus in map generalization for a long time. Based on the Fourier technique, this paper proposes a continuous, multi-scale representation model for progressive transformation of cartographic curves on the Internet. In our method, all the curves, whether closed or open, are depicted as periodical functions which are further expressed as Fourier series. The convergence degrees of the Fourier series are explored for different kinds of curves, and truncating frequencies are derived based on the similarity between the original and reconstructed curves. Using information theory and the Radical Law in cartography, the relationship between map scales and Fourier frequencies is established. Based on the proposed multi-scale model, we also introduce the principles and implementation of a progressive transmission method. Our method is evaluated using the contours from a topographic map. The results show that our model is a valid approach to multi-scale representation of cartographic curves.  相似文献