Influence of Uneven Trace Spacing on Rayleigh Wave Dispersion

Rayleigh wave dispersion signals are significant to underground investigation.Tradition-ally,uniformed trace spacing is employed in surface wave surveys.In some cases,however,uneven trace spacing is often encountered because of the limitations of the site condition.In order to study the influence of uneven trace spacing on the dispersion data construction of Rayleigh waves,data acquisi-tion is performed based on a 2.5D field layout with a linear array of geophones fixed and a mobile source.The observation d...     

Hybrid Sedimentation in Late Permian-Early Triassic in Western Sichuan Basin,China

Mixed carbonate-siliciclastic sedimentation is common in the Upper Permian-Lower Tri-assic in the western Sichuan(四川) basin.The extensional movement was strong in the Late Permian,resulting in differential uplifting of fault blocks.During this period,there was an extensive retrogres-sion.The Kangdian(康滇) ancient land progressive uplifted and enlarged,forming the major prove-nance of terrigenous clastics.In Changxingian age,mixed terrigenous-carbonate sedimentation was dis-tributed in the area between Dafeis...     

Comparison of Results of Recent Seismic Profiles with Tectonic Models of the North China Craton

The geometry and timing of amalgamation of the North China craton(NCC) have been controversial,with three main models with significantly different interpretations of regional structure,geochronology,and geological relationships.The model of Zhao G C et al.suggests that the eastern and western blocks of the NCC formed separately in the Archean,and an active margin was developed on the eastern block between 2.5 and 1.85 Ga,when the two blocks collided above an east dipping subduc-tion zone.The model of Kusky ...     

Postrift Rapid Subsidence Characters in Qiongdongnan Basin,South China Sea

In this article,the backstripping technique was used in studying the subsidence charac-ters of the Qiongdongnan(琼东南) basin(QDNB) in order to understand its dynamic mechanism of formation and evolution.Meanwhile,the geothermal characteristics of this area were summarized,and the stretching factors(β) of the upper crust,the whole crust,and the whole lithosphere were calculated.The QDNB is characterized by high subsidence rate,high geothermal gradient,high geothermal heat flow,and the lithosphere stretching an...     

美国地质灾害防治现状综述

地质灾害的防治研究受到世界各国的广泛重视,本文从地灾防治基础理论、职能部门工作方式入手,对美国科研界的非饱和土理论最新研究进展、美国地质调查局(USGS)地质灾害防治中心的日常工作形式进行了较为全面的阐述。除此之外,还结合作者自身参与的滑坡灾害调研活动,对美国科研人员的野外基本工作方法、野外工作的最主要目的进行了描述。在此基础上,还对中美两国地灾防治现状进行了简要对比,本文所阐述的内容可为相关领域的研究人员提供一定的参考。     

内蒙古锡林郭勒杂岩解体及表壳岩系年代确定

近年来,对中亚造山带中是否存在微地块有诸多不同看法,其中对广泛出露的锡林郭勒杂岩的时代和原岩认识存在较大的分歧。经大比例尺填图和详细露头解剖发现,它囊括了不同岩类、不同变质程度、不同构造样式和形成时代的地质体。文中建议将其解体,对其中被厘定的表壳岩命名为＂锡林浩特岩群＂,这是一套达到角闪岩相变质的夹有火山岩和磁铁石英岩...     

南堡凹陷东营组高精度层序地层格架及沉积体系分析

在高分辨率三维地震、钻井以及大量地质资料研究基础上,根据层序地层界面特征,将南堡凹陷东营组划分为1个二级层序和4个三级层序。以初始洪泛面和最大洪泛面识别特征为依据,进一步将三级层序划分出体系域。通过层序地层格架特征及其发育位置分析,认为柳南次凹层序地层格架发育的主控因素为构造、物源和湖平面变化。应用层序地层学原理及南堡凹陷沉积充填背景研究,认为柳南次凹的沉积体系类型为冲积扇、扇三角洲、水下扇、重力流及湖泊沉积体系。冲积扇及水下扇体系在低位体系域中发育,高位体系域中扇三角洲体系和重力流发育,湖扩体系域中湖泊体系非常发育。     

滇东地区煤田构造格局与煤系赋存规律的研究

滇东地区位于特提斯和环太平洋构造体系的交接部位,煤田构造格局的总体特征是呈NNE向条带状展布。区内断层以NNE、NE向为主,受主要断裂影响,煤田在南北向呈带状,东西向呈段状展布,各煤矿区在平面上呈NE向带状分布。研究区煤系赋存受基底主干断裂的控制作用明显,变形强度由北向南逐渐增强,北部地区以褶皱构造为主,断层较少,煤层多保存于向斜构造中,保存较完整,煤层埋藏较深;南部受弥勒-师宗断裂带影响,断裂构造极为发育,对煤层破坏严重,煤系赋存不稳定。     

珠江口滨海湿地退化现状、原因及保护对策

2007年和2008年秋季对珠江口滨海湿地进行了环境现状综合调查,结果表明,珠江口滨海湿地退化主要表现在4个方面:天然湿地面积减少、湿地生产力不断下降、湿地环境状况持续恶化和湿地景观破碎化。珠江口滨海湿地退化的原因主要为滩涂开发与围填海、污染物排放、养殖污染、海平面上升、过度捕捞、海砂开采和港口码头建设以及水土资源开发等因素。滨海湿地保护与利用对策主要有:制定有关滨海湿地保护的法律法规和湿地保护与利用规划;加强人才队伍建设和滨海湿地有关技术研究;建立滨海湿地动态监测体系;加大滨海湿地保护区建设的力度;加强宣传和教育。     

东吴运动的沉积学响应——以湘鄂西及邻区二叠系茅口组顶部不整合面为例

湘鄂西及邻区二叠系茅口组顶部广泛发育了岩溶角砾岩,并形成了一个分布范围广阔的不整合面,该不整合面特征在各地存在明显差异,其上覆孤峰组与龙潭组也存在不同程度的缺失。东吴运动为两幕式构造运动,上述现象正是东吴运动Ⅰ幕、Ⅱ幕在不同地区的沉积学响应。