综合地球物理调查技术在江苏如东滩涂区栟茶河断裂空间展布中的应用     

李飞 《地质与勘探》2020,56(3):566-579

本文依据江苏如东滩涂区综合地球物理调查工作，对小洋口地区断裂构造空间展布进行了解译，分析了解译断裂与栟茶河断裂的关系。解译结果主要参考实测无人机航磁资料，辅以浅层地震和电磁法资料。综合两个子测区的断裂构造解译结果，同时参考华东地区航磁和重力资料，对栟茶河断裂的空间展布位置进行了推断，认为其是近EW向大型断裂，延伸距离长，同时控制测区其他断裂的展布。实测数据未发现金坛—如皋断裂在测区范围内存在的地球物理证据，分析认为其未发育至栟茶河断裂以北。  相似文献   

Three-dimensional active earth pressure from cohesive backfills with tensile strength cutoff     

Zheng-Wei Li  Tian-Zheng Li  Xiao-Li Yang 《国际地质力学数值与分析法杂志》2020,44(7):942-961

Most of previous analyses on the active earth pressure were performed in two-dimensional cases using the Mohr-Coulomb (M-C) failure function to describe the soil strength. However, all failures of retained slopes indicate a somewhat three-dimensional (3D) feature, and the M-C function is found to overestimate the tensile strength of cohesive soil. In this work, a kinematic limit analysis–based approach is developed for computing the 3D active earth pressure resulting from cohesive backfills. The concept of tensile strength cutoff is adopted to implement the reduction or elimination of tensile strength from the strength envelope. An extended 3D horn failure mechanism that is associated with the modified strength envelope is developed to characterize the collapse of retained slopes. The resultant of active earth pressure is evaluated from the work rate balance equation and expressed as an unfactored coefficient. The obtained results indicate that less support provided by the wall is required when allowing the existence of soil cohesion and 3D effects and that eliminating the tensile strength can observably increase the active earth pressure, especially for the backfill with a great level of cohesion.  相似文献   

郯庐断裂带南段继承性断裂构造控矿模式研究及其应用效果——以皖东北五河金矿整装勘查为例     

汪青松  张顺林  张金会  张家嘉  尤淼 《地质学报》2020,94(10):2965-2977

郯庐断裂带南段的皖东北地区地质构造复杂，多为厚覆盖区，找矿难度大。由于控矿条件难以调查清楚，缺乏具有区域特色的勘查理论指导，区内金矿勘查长期没有取得突破成果。笔者依托五河金矿整装勘查项目，进行了区域重磁异常特征和成矿规律分析研究，发现皖东北地区北东- 北北东向重力低异常具有弧形条带特征，并以郯庐断裂带为界，大致具有旋转对称性。重磁异常保存印支期构造格架痕迹信息，反映了郯庐断裂带南段时空演化特征，显示了北东- 北北东向主要断裂构造具有继承性，形成于印支期，燕山期继续活动，控制白垩纪“红层盆地”和燕山期成岩成矿作用。中低温热液型金多金属矿床和矽卡岩型铜金矿床是皖东北地区主要矿床类型，均受继承性断裂构造控制。结合郯庐断裂的演化特征，利用物探成果引领地质理论创新，提出了郯庐断裂带南段矿床的“继承性断裂构造控矿模式”。根据继承性断裂构造形成机理分析其空间分布规律，总结了矿化蚀变构造带的物探异常标志，解决了皖东北覆盖区成矿预测与找矿靶区圈定难题，在五河金矿整装勘查区应用取得了重要找矿成果，圈定6个金矿找矿靶区，得到了钻探验证，已发现中型规模金矿床2处、小型3处，估算潜在资源量可达特大型规模，实现了安徽省境内郯庐断裂带金矿找矿的重大突破。  相似文献   

大兴安岭西侧盆地群推覆构造的地震学证据          下载免费PDF全文

王典  李鹏  单玄龙  鹿琪  刘洋  于涵 《地球物理学报》2019,62(3):1129-1138

推覆构造是一种和油气有关的重要构造形式,主要产出于造山带前陆,是挤压或压缩作用的结果,对油气的生成、储集、运移、圈闭和保存条件都有着重要的影响.研究区从漠河盆地、海拉尔盆地到二连盆地内的中生代推覆构造,组构了大兴安岭西盆地群推覆构造.本文通过对三个盆地五种推覆构造的地震学研究,将其推覆方向归结为两类:第一类由北西向南东推覆,在三个盆地中表现明显;第二类由南东向北西推覆,在海拉尔盆地和二连盆地内有显示.认为第一类推覆作用来源于蒙古—鄂霍茨克洋自西向东的闭合;第二类推覆作用来源于太平洋板块俯冲的远程应力作用.  相似文献   

Active channel width as a proxy of sediment supply from mining sites in New Caledonia     

Mélanie Bertrand  Frédéric Liébault 《地球表面变化过程与地形》2019,44(1):67-76

Although the channel morphology of upland fluvial systems is known to be strongly controlled by sediment supply from hillslopes, it is still difficult to isolate this effect from the other controlling factors of channel forms, such as the sediment transport capacity (depending notably on the size of the catchment) and local conditions (e.g. confinement, riparian vegetation, valley-floor slope). The rivers in New Caledonia offer an interesting field laboratory to isolate the morphological effect of contrasted sediment supply conditions. Some of these rivers are known to be highly impacted by the coarse sediment waves induced by the mining of nickel deposits that started in the early 1870s, which was particularly intensive between the 1940s and 1970s. The propagation of the sediment pulses from the mining sites can be traced by the presence of wide and aggraded active channels along the stream network of nickel-rich peridotite massifs. A first set of 63 undisturbed catchments in peridotite massifs distributed across the Grande Terre was used to fit a classic scaling law between active channel width and drainage area. A second set of 86 impacted sites, where the presence of sediment waves was clearly attested by recent aerial imagery, showed systematically wider active channels, with a width ratio around 5 (established from the intercept ratio of width–area power laws). More importantly, this second set of disturbed sites confirmed that the residual of active channel widths, computed from the scaling law of undisturbed sites, is statistically positively related to the catchment-scale relative area of major mining sediment sources. It is therefore confirmed that the characterization of sediment supply conditions is crucial for the understanding of spatial patterns of active channel width, and this should be more thoroughly considered in morphological studies of rivers draining environments with contrasted geomorphic activities on hillslopes. © 2018 John Wiley & Sons, Ltd.  相似文献   

太行山南端浅层速度结构成像和隐伏断裂探测   总被引：1，自引：0，他引：1  

徐增波  刘保金  姬计法  鄷少英  袁洪克  谭雅丽  王宏伟 《大地测量与地球动力学》2019,39(1):88-92

利用太行山南端的深地震反射剖面数据，运用初至波层析成像方法反演得到该区域的浅层P波速度结构和基底面展布形态，发现剖面浅部的P波速度变化与沉积盖层厚度和断裂分布有着较好的对应关系。利用跨断裂完成的浅层地震反射剖面，对区域内2条第四纪隐伏活动断裂进行高分辨率成像。结果表明，汤西断裂为东倾的正断层，控制汤阴地堑的西边界，活动年代为中更新世；汤东断裂为西倾的正断层，是汤阴地堑的主控边界断裂，活动年代为晚更新世。  相似文献   

两郧断裂郧县盆地段地质与地球物理特征研究     

林松  李媛  王薇  廖武林  乔岳强 《大地测量与地球动力学》2019,39(2):148-152

通过野外地质调查，结合地球物理探测手段，研究两郧断裂郧县盆地段地质与地球物理特征；参照两郧断裂带多个位置采集断层物质的SEM、TL测试成果，并结合本次对断层上断点沉积物OSL测年数据，对两郧断裂该段第四纪活动性进行分析。研究结果表明，两郧断裂在郧县盆地段埋深相对较深；断裂特征主要为逆断层，部分分支断裂显示为正断性质；断裂带最新活动时代为中更新世晚期-晚更新世早期。  相似文献   

Conjugate ruptures and seismotectonic implications of the 2019 Mindanao earthquake sequence inferred from Sentinel-1 InSAR data     

《International Journal of Applied Earth Observation and Geoinformation》2020

In 2019, four strong earthquakes of Mw>6.4 occurred successively in Mindanao, Philippines. Based on the reports from the USGS and PHIVOLCS, these earthquakes were dominated by strike-slip ruptures. Whether these earthquakes are temporally and spatially related remained unknown. We characterized the coseismic displacement fields during the earthquake sequence using an InSAR technique with Sentinel-1 SAR data. The InSAR deformation measurements convincingly reveal that the four earthquakes produced distinct coseismic displacement patterns. We estimated the source parameters of the earthquakes with a two-step inversion strategy. The optimal model suggests that the earthquake sequence resulted from the reactivation of a conjugate fault structure that involves two nearly vertical left-lateral strike-slip faults and two high-angle right-lateral strike-slip faults. We calculated Coulomb stress changes from the earthquake sequence, suggesting that the previous strong earthquakes had significant stress-encouraging effects on the following events. The regional velocities based on the GPS analysis suggest that the formation of this conjugate structure is mainly due to the westward movement of the subducting Philippine Sea Plate. This earthquake sequence provides a seismotectonic background for subsequent strong earthquakes and helps to better understand the formation mechanisms and seismotectonic implications of conjugate structure rupturing.  相似文献   

利用模板匹配技术检测米尺度岩石断层黏滑实验中的声发射事件   总被引：1，自引：0，他引：1       下载免费PDF全文

侯金欣  谢凡  任雅琼  王宝善 《地球物理学报》2020,63(4):1630-1641

声发射观测是岩石摩擦实验中研究强震孕育机制的重要观测手段之一.传统的声发射观测以触发记录为主,难以捕捉并提取微弱的声发射信号.近年来天然地震学中发展的模板匹配技术可以在连续波形记录中识别出微弱的事件,大大提升事件检测能力.本文发展了适用于多通道连续记录的声发射信号的模板匹配技术,并将该技术应用于分析米尺度岩石断层黏滑失稳过程.研究结果显示:模板匹配技术识别出的声发射数量约为传统方法识别的5倍,相对完备震级降低约0.3.临近失稳,检测目录完备震级以上声发射率表现出幂律增加的特征,且声发射事件聚集在失稳破裂起始点附近.失稳后,检测目录完备震级以上声发射率表现出幂律衰减,其中失稳后早期表现出较慢的衰减速度.另外,失稳后早期声发射事件表现出随对数时间沿断层迁移的趋势.最后,通过与天然地震学观测的结果对比表明,声发射模板匹配识别技术是研究大尺度岩石摩擦滑动失稳过程中前震和余震时空演化规律的有效手段,该技术助于在方法上为室内实验和野外观测进行融合研究提供思路.  相似文献   

太行山东麓汤西断裂南段活动特征分析     

戴骜鹏  刘明军  贺为民  孙译 《大地测量与地球动力学》2020,40(6):571-576

采用槽探、年代样品测试、阶地调查和形变测量监测等方法，对太行山东麓汤西断裂南段进行研究，分析其活动特征。结果表明，汤西断裂发育于中更新世，历经多次活动，断裂并未上延到上更新统地层中，其南段的活动强度较高，最新活动年代为中更新世；汤西断裂西代村场地的垂直形变监测（1999~2014年）结果存在异常，综合监测点数据和区域新构造特征分析发现，该异常可能是研究区区域形变场的反映，并非由汤西断裂活动引起。  相似文献