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   

中国海域1:100万区域地质调查主要成果与认识          下载免费PDF全文

秦绪文  石显耀  张勇  李学杰  李军  肖桂义  许振强  王宏斌  吕文超  吴浩  姚永坚  尚鲁宁  杨楚鹏  王中波  高红芳  王明健  密蓓蓓  钟和贤  胡刚  陈泓君  黄龙  罗伟东  梅西  徐子英  田陟贤  王忠蕾 《中国地质》2020,47(5):1355-1369

中国海域及邻区是建设“21世纪海上丝绸之路”、打造海洋命运共同体和推动可持续发展的关键地区，也是地球科学最具有典型性和代表性的研究区域之一。中国管辖海域1：100万区域地质调查是一项以国家需求为导向、以解决重大地球系统科学问题为目标的基础性公益性工作。中国地质调查局通过近20年的持续调查，实现了对中国管辖海域1：100万区域地质调查的全面覆盖，系统地获取了海洋地质和地球物理基础数据，形成了基于实测数据的“一图一库一报告”，大幅提升了中国海洋地质调查工作程度。这项工作填补了中国小比例尺海洋地质国情调查的空白，初步摸清了中国管辖海域地质环境条件和资源环境潜力，取得了一批原创性的认识，为建设海洋强国提供了详实可靠的地质资料，为提升区域地质科学的认知水平奠定了坚实基础。  相似文献   

内蒙古狼山地区早二叠世花岗闪长岩的年代学、地球化学特征及其构造背景     

田健  滕学建  刘洋  滕飞  郭硕  何鹏  王文龙 《中国地质》2020,47(3):767-781

内蒙古狼山山脉西侧分布有大面积的晚古生代岩浆岩,其时代集中在早石炭世—晚二叠世,不同时代岩浆岩岩石组合对于认识狼山地区晚古生代构造背景具有重要的意义。文章通过岩石学、岩相学、地球化学及Hf同位素等方法,对狼山地区查干乃呼都格一带花岗闪长岩体进行了研究。该岩体岩性为花岗闪长岩,LA-ICP-MS锆石U-Pb年龄显示,其206Pb/238U加权平均年龄为(299±1)～(293±2) Ma。岩石暗色矿物为角闪石及黑云母,富含闪长质包体,P_2O_5含量与SiO_2含量之间显示良好的负相关性,富钠(Na_2O含量为3.45%～4.96%),高钠钾比值(Na_2O/K_2O比值为1.33～2.52),岩石地球化学特征显示花岗岩成因类型为Ⅰ型花岗岩。岩石具有负的ε_(Hf)(t)值(-6.3～-2.0)及T_(DM2)为1437～1704 Ma(平均值为1606 Ma),显示了古—中元古代古老地壳熔融的特点,ε_(Hf)(t)-t及角闪石成因图解显示源区有幔源岩浆参与。花岗岩富集大离子亲石元素Rb、K、Pb,不同程度的亏损高场强元素Nb、Ta、P、Ti,轻稀土富集,重稀土亏损,弱的负Eu异常,显示了岩浆弧的地球化学特征。结合晚石炭世—早二叠世狼山地区侵入岩岩石组合为闪长岩+石英闪长岩+花岗闪长岩(英云闪长岩),早—中二叠世大石寨组火山岩岩石组合为玄武岩+玄武安山岩+安山岩+英安岩,总体反映了陆缘弧的岩石组合;狼山地区早二叠世处于大陆边缘弧的构造背景,与华北地块北缘中东部可以对比。  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   

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   

Method‐dependent influence of environmental variables on reef fish assemblages when comparing trap and video surveys     

Nathan R. Geraldi  Nathan M. Bacheler  G. Todd Kellison 《Marine Ecology》2019,40(1)

Despite substantial survey effort and a large body of literature on abiotic and biotic factors in temperate reef ecosystems, knowledge of the complex and interactive effects of environmental variables on those communities is limited. Various survey methods have been developed to study environmental predictors of biodiversity, but there remains a gap in our understanding of how survey results are influenced by environmental factors. Here, we surveyed the fish assemblage associated with southeastern U.S. temperate marine reefs with simultaneous, paired trap, and camera gears throughout a ~50,000 km² area during 2011–2013 and assessed the influence of environmental variables on the trap‐ and video‐surveyed assemblages. Predictor variables in the multivariate general linear models included depth, temperature, month, year, location, substrate relief, percent sessile biota, biota type, and turbidity. Depth and latitude had the greatest influence on the fish assemblage for both gears. The influence of habitat variables differed between methods and percent biota explained more variation in the fish assemblage when assessed by traps, while substrate relief and biota type explained more variation in the fish assemblage when assessed by video. In general, habitat complexity was positively related to the abundance of fishes in the video survey, but there was a negative relationship in the trap survey. Differences between gears were species‐specific and the influences of environmental variables were similar for some species such as Haemulon plumierii and Hyporthodus niveatus. The methods presented here can be used to assess method‐dependent differences in fish assemblages, which is a necessary precursor to assess the effect of environmental variables on the accuracy of surveys.  相似文献   

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China     

《China Geology》2020,3(3):462-472

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain, the transition zone between the Dabie Mountain Area and Jianghan Plain. It’s a great field test site to study the material and energy exchange among rainfall, soil moisture, and groundwater of the Earth ’s critical zone in subtropical monsoon climate plain areas. This paper analyzed the connection between rainfall and volume water content (VWC) of soil at different depths of several soil profiles, and the dynamic feature of groundwater was discussed, which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata. The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge, while the lateral recharge is the main supplement source. There were 75 effective rainfall events among 120 rainfall events during the monitoring period, with an accumulated amount of 672.9 mm, and the percentages of effective rainfall amount and duration time were 62.50% and 91.56%, respectively. The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m. The soil profile was divided into four zones: (1) The sensitive zone of rainfall infiltration within 1.4 m, where the material and energy exchange frequently near the interface between atmosphere and soil; (2) the buffer zone of rainfall infiltration between 1.4 m and 3.5 m; (3) the migration zone of rainfall infiltration between 3.5 m and 5.0 m; and (4) the rainfall infiltration and groundwater level co-influenced zone below 5.0 m. The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth ’s critical zone, which is of great theoretical and practical significance for groundwater resources evaluation and development, groundwater environmental protection, ecological environmental improvement, drought disaster prevention, and flood disaster prevention in subtropical monsoon climate plain areas.  相似文献   

Geochemical characteristics and sedimentary environment of the Middle Devonian organic-rich shales in the Northwest of Guizhong Depression,Southwest China     

《China Geology》2020,3(4):567-574

In order to figure out the redox conditions and paleo-sedimentary environment of the Middle Devonian shales in the northwest of Guizhong Depression, the trace element analysis was conducted on the Middle Devonian cores (320.35–938.50 m) of the typical shale gas investigation well (GY-1) at a 1.50 m sampling interval through X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). According to the test result, the average values of V/(V+Ni), V/Cr and Ni/Co in Nabiao formation (Fm.) are larger than 0.67, 4.65 and 7.71 respectively, and Nabiao Fm. is rich in biological assemblages such as tabasheer, ammonite, etc. These evidences indicate the rising sea level rose relatively in the sedimentation period of Nabiao Fm. and a deepwater shelf environment, which was favorable for the preservation of organic matters. The V/(V+Ni), V/Cr and Ni/Co in Luofu Fm. and Tangting Fm. are 0.38–0.65, 0.73–4.10 and 3.70–6.72 respectively, indicating that the sea level dropped relatively in their sedimentation period, during which the water bodies became shallow, and the sedimentary environment was a weak oxidizing shallow water shelf environment. In addition, the variation of TOC has a high correlation with the enrichment degree of Ba element, indicating the favorable conditions for the enrichment and preservation of organic matters under an oxygen-deficient environment. Moreover, according to the identification of trace element indexes, the northwest of Guizhong Depression experienced the sedimentary cycle of relative rise to relative fall of sea level from bottom to top in the Middle Devonian sedimentation period. The relative sea level rose to the highest in the sedimentation period of Nabiao Fm., in which the organic-rich shales with stable thickness and high organic content were deposited. Hence, the Nabiao Fm. could be regarded as the favorable exploration target interval in this area.  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