On how thin submarine flows transported large volumes of sand for hundreds of kilometres across a flat basin plain without eroding the sea floor     

Christopher J. Stevenson  Peter J. Talling  Esther J. Sumner  Douglas G. Masson  Micheal Frenz  Russell B. Wynn 《Sedimentology》2014,61(7):1982-2019

Submarine gravity currents, especially long run‐out flows that reach the deep ocean, are exceptionally difficult to monitor in action, hence there is a need to reconstruct how these flows behave from their deposits. This study mapped five individual flow deposits (beds) across the Agadir Basin, offshore north‐west Africa. This is the only data set where bed shape, internal distribution of lithofacies, changes in grain size and sea floor gradient, bed volumes, flow thickness and depth of erosion into underlying hemipelagic mud are known for individual beds. Some flows were 30 to 120 m thick. However, flows with the highest fraction of sand were less than 5 to 14 m thick. Sand was most likely to be carried in the lower 5 to 7 m of these flows. Despite being relatively thin, one flow was capable of transporting very large volumes of sediment (ca 200 km³) for large distances across very flat sea floor. These observations show that these relatively thin flows could travel quickly enough on very low gradients (0·02° to 0·05°) to suspend sand several metres to tens of metres above the sea floor, and maintain those speeds for up to 250 km across the basin. Near uniform hemipelagic mud interval thickness between beds, and coccolith assemblages in the mud caps of beds, suggest that the flows did not erode significantly into the underlying sea floor mud. Simple calculations imply that some flows, especially in the proximal part of the basin, were powerful enough to have eroded hemipelagic mud if it was exposed to the flow. This suggests that the flows were depositional from the moment they arrived at a basin plain location, and that deposition shielded the underlying hemipelagic mud from erosion. Reproducing the field observations outlined in this exceptionally detailed field data set is a challenge for future experimental and numerical models.  相似文献   

几何平均重力归一化总梯度在山东招远金矿采空区的应用     

苏超  杜晓娟  马国庆  周文纳 《世界地质》2014,33(4):889-894

传统方法对重力异常的总梯度作归一化计算时,通常是对总梯度的模作算术平均。笔者对归一化函数的分母分别作了几何平均、调和平均、修匀平均和中值平均,计算归一化函数。通过模型试验对比这四种不同的统计平均,其中几何平均重力归一化总梯度在进行反演计算时,抗噪能力更强,反演结果更加集中、准确。将该方法应用于山东招远金矿采空区,改进后的方法可以更加准确地确定采空区的水平位置和中心埋深。  相似文献   

“走出去”利用国外油气资源的区域选择     

于春林  岳来群  潘继平  姜文利  王越  申延平 《地质通报》2006,(Z2)

近年来中国油气供需矛盾日益突出“,走出去”利用国外油气资源战略已成为国民经济可持续发展的一项重要内容,但世界油气资源地理分布不均,影响国外油气供给的因素纷繁复杂,因此,进行客观、可操作性强的区域选择非常必要。本文依据油气资源潜力、投资环境、地理位置和与中国的外交关系4个标准对中国利用国外油气资源的区域选择进行了全面的分析,并确定了中亚和俄罗斯、中东和北非、东南亚、南美4个战略区域。  相似文献   

孔中电磁波透视在煤窑采空区勘探中的应用实例   总被引：2，自引：0，他引：2  

王文龙 《物探与化探》1999,23(4):314-316

在山西地方铁路病害整治的勘探过程中,将电磁波孔间透视法应用于寻找煤窑采空区,取得了良好的地质效果.  相似文献   

薄层地震响应分析及识别技术   总被引：3，自引：0，他引：3  

李勤学  付雷 《世界地质》1999,18(4):91-95

对薄层地震响应的振幅,频谱等特征进行了详细的分析,并分析了影响该地震的应波形特征的因素。同时,利用积分能谱技术对其进行处理,可以识别出薄层的厚度变化及透镜体的存在。实际应用表明,该项技术较常规的时频分析方法有更高的分辨能力。  相似文献   

长沙滨江文化园音乐厅工程施工测量技术     

许宁  何勇  张建坤 《测绘信息与工程》2010,35(2):23-24

采用了测量机器人和GPS并结合AutoCAD辅助计算,介绍了长沙市滨江文化园音乐厅工程施工测量,实现了节约成本、控制工期的目的,达到了较高的精度。  相似文献   

Analytical model for the out‐of‐plane response of vertically spanning unreinforced masonry walls          下载免费PDF全文

Michele Godio  Katrin Beyer 《地震工程与结构动力学》2017,46(15):2757-2776

An analytical model describing the flexural response of vertically spanning out‐of‐plane loaded unreinforced masonry walls is presented in this paper. The model is based on the second‐order Euler‐Bernoulli beam theory and captures important characteristics of the out‐of‐plane response of masonry walls that have been observed in experimental tests and from numerical studies but for which an analytical solution was still lacking: the onset and the evolution of cracking, the peak strength of the out‐of‐plane loaded walls, and the softening of the response due to P ?Δ effects. The model is validated against experimental results, and the comparison shows that the model captures both the prepeak and postpeak response of the walls. From the analytical model of the force‐displacement curve, a formula for the maximum out‐of‐plane strength of the walls is derived, which can be directly applied in engineering practice.  相似文献   

跨图幅任意区域管网空间数据的裁剪输出   总被引：2，自引：0，他引：2  

任杰  马民涛  陈克龙  赵永梅 《测绘与空间地理信息》2006,29(4):35-37

简单介绍了城市综合管网管理信息系统中管网空间数据的组成以及跨图幅任意区域管网空间数据的裁剪输出功能,详细阐述了裁剪输出功能的工作流程设计、裁剪输出功能实现的关键以及裁剪输出功能具体的实现工程。裁剪输出功能是城市综合管网管理信息系统的一项重要功能,利用裁剪输出功能可以方便地对管网空间数据按照所需区域、所需专题进行裁剪输出,这对于现场施工、管网勘察等相关工作具有重要的指导作用,它搭建了城市综合管网管理系统与用户之间的桥梁。  相似文献   

光纤传感器在双翻斗雨量传感器超差调整中的应用          下载免费PDF全文

满永恒  刘振涛  王静 《气象科技》2022,50(4):606-610

双翻斗雨量传感器标校过程中，对于不同雨强超差方向相反的雨量计需要分别调节上翻斗的定位螺钉和计量翻斗的容量调节螺钉，同时也需要记录上翻斗和计量翻斗的翻动次数。雨量计使用的是无源脉冲输出，计量翻斗的每次翻动触发干簧管产生一个脉冲，利用单片机即可采集这个信号自动记录。而上翻斗的翻动次数靠人工观察统计，由于翻斗翻动速度较快人工计数不准确，最终造成标校不准。并且人工每次只能记录1台雨量计，无法批量自动记录数据。本文采用光纤传感器在不干扰雨量计运行情况下自动统计上翻斗翻动次数，为标校提供准确数据。  相似文献   

1956～2005年鄱阳湖入出湖悬移质泥沙特征及其变化初析   总被引：9，自引：0，他引：9  

闵骞  时建国  闵聃 《水文》2011,31(1):54-58

利用江西省五大河流控制水文站与湖口水文站实测悬移质泥沙资料,分析鄱阳湖1956～2005年入出湖悬移质泥沙基本特征,揭示鄱阳湖入出湖悬移质泥沙在近50年的变化状况及其形成原因;在此基础上探讨鄱阳湖悬移质泥沙平衡情况及其发展态势。表明近20年鄱阳湖入湖悬移质泥沙逐渐减少,近10年出湖悬移质泥沙大幅增多,湖盆容积呈现出快速加大的趋势。  相似文献