Acoustic properties of deformed rocks in the Nobeoka thrust,in the Shimanto Belt,Kyushu, Southwest Japan          下载免费PDF全文

Yoshitaka Hashimoto  Shogo Abe  Hiroki Tano  Gaku Kimura  Asuka Yamaguchi  Rina Fukuchi  Jun Kameda  Yohei Hamada  Yujin Kitamura  Koichiro Fujimoto  Mio Eida 《Island Arc》2017,26(4)

Laboratory measurements for compressional and shear wave velocities (Vp and Vs, respectively) and porosity were conducted with core samples from the Nobeoka Thrust Drilling Project (NOBELL) under controlled effective pressure (5–65 MPa at 5 MPa intervals) and wet conditions. Samples were classified according to deformation texture as phyllite, foliated cataclasite, or non‐foliated cataclasite. Measured values of Vp, Vs, and porosity are within a range of 5.17–5.57 km/s, 2.60–2.71 km/s, and 2.75–3.10 %, respectively, for phyllite; 4.89–5.23 km/s, 2.46–2.57 km/s, and 3.58–4.53 %, respectively, for foliated cataclasite; and 4.90–5.32 km/s, 2.51–2.63 km/s, and 3.79–4.60 %, respectively, for non‐foliated cataclasite, which are all consistent with the previous laboratory experiments conducted with outcrop samples under dry conditions. However, our results also indicate higher Vp and Vs and lower porosity than those measured by the previous studies that adopted the wire‐line logging methods. The variations in Vp, Vs, and porosity are controlled by deformation structure and are greater for phyllite and foliated cataclasite than for non‐foliated cataclasite.  相似文献   

阿尔金断裂南侧弧形地貌单元成因及其构造意义     

栗兵帅  颜茂都  张伟林  杨永鹏  张大文  陈毅  关冲 《地震地质》2019,41(2):300-319

巨型左旋走滑的阿尔金断裂是青藏高原的北部边界,在印度-欧亚板块碰撞过程中起重要的调节作用,控制着青藏高原东北部的构造演化,认识其活动演化对理解青藏高原的构造变形过程和机制具有重要意义。阿尔金断裂南侧存在一系列弧形地貌单元,知晓这些弧形带是原始弧形弯曲还是后期由于阿尔金断裂左旋走滑拖曳而形成的,对认识阿尔金断裂的构造演化具有重要意义。文中在前期阿尔金断裂南侧柴西英雄岭和柴北缘2条弧形带不同部位已开展的精细古地磁旋转变形研究的基础上,综合研究区和阿尔金断裂附近已有的古地磁旋转变形研究结果和弧形带几何形态学等其它地质证据,分析发现这2条弧形带的几何学特征是由其不同部位发生旋转变形所导致的,且旋转变形与该时段阿尔金断裂的快速左旋走滑活动密切相关。通过上述工作,更加全面地了解了阿尔金断裂新生代2阶段的走滑特征,进一步限定了阿尔金断裂早渐新世以来左旋滑移量,以柴西段为参照系滑移量至少约350～430km,以柴北缘段为参照系至少约380～460km,平均滑移速率至少约10. 6～13. 9mm/a。  相似文献   

东海陆架盆地北部新构造运动特征     

侯方辉  张志珣  张训华  李三忠  温珍河  李日辉  郭兴伟  李达 《海洋地质前沿》2010,(11)

根据最新单道地震剖面及解释成果,分析了东海陆架盆地北部新构造运动特征。研究表明:研究区新构造期差异升降运动明显,从中新世到第四纪,沉降中心自西向东迁移;研究区活动断裂以NE—NNE和近EW向为主,新构造期的活动性自西向东逐渐变新;研究区新构造期岩浆活动频繁,多沿断裂分布,大致可划分为3期,平面上自西向东逐渐变新,且侵入活动逐渐减弱,喷发活动逐渐增强。  相似文献   

西藏冈底斯银多金属矿化带的基本特征与成矿远景分析   总被引：16，自引：6，他引：10  

孟祥金  侯增谦  叶培盛  杨竹森  李振清  高永丰 《矿床地质》2007,26(2):153-162

在冈底斯斑岩铜矿带的北侧,发育一条与之平行的银多金属矿化带。文章对该银多金属矿化带的成矿构造背景、矿床类型及矿化特点进行了初步分析与总结。研究结果表明,该矿化带受旁多—措勤逆冲系的控制,呈近EW向带状展布,带内矿床多位于EW向逆冲断裂与近NS向张性构造的交汇部位;主要矿化类型为矽卡岩型和热液脉型;据矿化特点差异,以念青唐古拉为界,可分为东、西2段,东段以矽卡岩型Cu-Pb-Zn-Ag矿化为主,西段以热液脉型Ag-Pb-Zn矿化为主,西段矿床的银含量明显高于东段。该矿化带是大陆碰撞造山晚期或后碰撞伸展早期(25～15Ma)热液活动的产物。综合对比分析显示,该矿化带具有良好的成矿条件及巨大的成矿潜力,有望发展成为一条规模巨大的银多金属成矿带。  相似文献   

The stratigraphy,structure and regional significance of the Moine Rocks of Mull,Argyllshire, W. Scotland     

R. E. Holdsworth  A. L. Harris  A. M. Roberts 《Geological Journal》1987,22(2):83-107

Two right-way-up Moine lithostratigraphic units—the Shiaba (older) and Assapol (younger) Groups—are distinguished in the Ross of Mull. These were intruded in the west by the post-tectonic, Ross-of-Mull granite complex at 414 ± 3 Ma. Apparently undisturbed inclusions of Moine metasediments within the granite permit the boundary between the lithostratigraphic units to be followed westward almost to the supposed trace of the Moine thrust in the Sound of Iona. The Shiaba and Assapol Groups which have a transitional, albeit attenuated, stratigraphic contact are correlated with the Morar and Glenfinnan Divisions of Inverness-shire, the Sgurr Beag ductile thrust (slide) normally found at the Morar/Glenfinnan Division boundary being absent. This implies that the stratigraphic relationship between these two divisions, which is elsewhere obscured by the thrust, is uniquely preserved on Mull. Within a local, D1-D4 sequence, D2 and D3 structures are dominant. Originally subhorizontal D2 folds are intensely curvilinear on all scales about an originally flat-lying, NNW-SSE trending stretching lineation (L2). In sections parallel to L2, D2 minor folds display a constant sense of vergence throughout the Ross-of-Mull Moine Rocks, overturning generally NW-NNW. The present day structure is dominated by the almost upright, SSW-plunging D3 Assapol synform which overprints all earlier structures. Tentative correlation of the deformation sequence with that of Inverness-shire, suggests that the D1-D2 structures of Mull, with accompanying moderate-to-high-grade metamorphism, may be Precambrian, while the D3 Assapol synform may be Caledonian. The presence of migmatites of kyanite grade means that metamorphic grade, established during MS1-MP2, is anomalously high for Moine rocks lying close to the supposed Caldonian front. This suggests that they may lie within one of the higher Caledonian thrust nappes of the North Highland Moine—possibly the Knoydart nappe, where metamorphic grade is comparable. The greenschist facies metamorphism and single phase of deformation affecting the ‘Torridonian’ rocks of Iona presents a significant contrast to the Moine rocks of the Ross of Mull. A major fault in the Sound of Iona is implied, but the Moine thrust itself probably does not outcrop.  相似文献   

塔里木盆地玛扎塔格构造带断裂构造分析   总被引：23，自引：9，他引：14       下载免费PDF全文

杨海军  李曰俊  冯晓军  郑民  张春  赵岩 《地质科学》2007,42(3):506-517

玛扎塔格构造带是麦盖提斜坡与巴楚断隆之间的一条边界断裂带,其中已发现和田河气田。断裂构造对于圈闭的形成和油气运聚成藏具有决定性的制约作用。通过系统的地震剖面解释,在玛扎塔格构造带识别出3期断裂构造:第1期构造活动以中寒武统的膏盐层为主滑脱面,由麦盖提斜坡向巴楚断隆冲断,伴生有断层传播褶皱发育,形成于新生界沉积之前,玛扎塔格背斜形成;这期冲断构造是本次研究的一个新发现。第2期活动为基底卷入型挤压走滑断裂,由相互背冲、近于平行的玛南断层和玛北断层组成,形成于中新世末,玛扎塔格背冲断块背斜形成。第3期活动以古近系底部的膏盐层为主滑脱面,由麦盖提斜坡向巴楚断隆冲断,也伴有断层传播褶皱发育,形成于更新世—全新世。在此基础上讨论了区域构造演化对玛扎塔格构造带3期断裂活动的形成和发育的控制。  相似文献   

Heat flow anomalies in the Gulf of Cadiz and off Cape San Vincente,Portugal     

Ingo Grevemeyer  Norbert Kaul  Achim Kopf 《Marine and Petroleum Geology》2009

Heat flow anomalies provide critical information in active tectonic environments. The Gulf of Cadiz and adjacent areas are affected by the plate convergence between Africa and Europe, causing widespread deformation and faulting. Active thrust faults cause lateral movement and advection of heat that produces systematic variations in surface heat flow. In December 2003 new heat flow data were collected during the research vessel Sonne cruise SO175 in the Gulf of Cadiz over two sites of recent focused research activity: (i) the Gulf of Cadiz sedimentary prism and (ii) the Marques de Pombal escarpment. Both features have also been discussed as potential source areas of the Great Lisbon earthquake and tsunami of 1755. Background heat flow at the eastern terminus of the Horseshoe abyssal plain is about 52–59 mW/m². Over the Gulf of Cadiz prism, heat flow decreases from ∼57 mW/m² to unusually low values of 45 mW/m² roughly 120 km eastward. Such low values and the heat flow trend are typical for active thrusting, supporting the idea of an east-dipping thrust fault. Slip rates are 10 ± 5 mm per year, assuming that the fault dips at 2°. A fault dipping at 5°, however, would result into slip rates of 1.5–5 mm per year, suggesting that subduction has largely ceased. Based on seismic data, the Marques de Pombal fault is interpreted as part of an active fault system located ∼100 km westward of Cape San Vincente. Heat flow over the fault is affected by refraction of heat caused by the 1 km high escarpment. Thermal models suggest that the slip rate along the fault must either be small or shear stresses acting on the fault are rather high. With respect to other fault zones, however, it is reasonable to assume that the fault's slip rate is small.  相似文献   

Experimental Study on Reaction Thrust Characteristics of Water Jet for Conical Nozzle     

黄国勤  李晓辉  朱玉泉  聂松林 《中国海洋工程》2009,23(4):669-678

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马尼拉俯冲带北段增生楔形态结构及演化过程     

王红丽  赵强  黄金莲  范建柯 《海洋科学》2019,43(8):1-16

为揭示马尼拉增生楔的形态结构并加深对其演化过程的理解,本文对横穿马尼拉俯冲带北段的几条典型地震剖面进行了深度偏移处理,得到叠前深度偏移剖面和深度-速度模型,并对马尼拉增生楔的形态结构及内部特征进行了精细解释,将马尼拉增生楔分为原始沉积段、褶皱变形段、逆冲推覆段和背逆冲段四个部分,分别代表增生楔演化的不同阶段。推断马尼拉增生楔下部存在由早期仰冲的菲律宾海板块的残留块体构成的弧前基盘,弧前基盘是控制马尼拉增生楔形成演化的关键构造。弧前基盘前端是拆离滑脱面突然降阶并在地震剖面上"隐没"的部位;弧前基盘向增生楔底部的不断挤入导致了逆冲脱序断层的渐次发育以及增生楔向弧前基盘之上的不断爬升,导致了增生楔上、下陆坡地貌的分化,并为褶皱变形段和逆冲推覆段的地层形变提供了主要的应力。  相似文献   

仿生胸鳍的三维尾涡结构与参数影响分析     

李宁宇  苏广胜  赵云鹤  孙向东  张嗣祺  苏玉民 《海洋工程》2020,38(1):66-76

为研究仿胸鳍推进的机理和流体动力特性及缩小机器鱼与生物原型之间的性能差距,利用浸入边界法数值模拟了做耦合旋转运动胸鳍的非定常绕流问题。详细探讨胸鳍非定常运动的三维尾涡结构演化和推进机理,并开展胸鳍推进性能与尾涡结构的参数影响分析。结果表明:迎流面在背、腹侧边缘及鳍梢部显著涡旋结构的作用下所出现的低压力区,加之鳍表面和上游来流之间好的垂直度共同造成了在动力划水阶段的高推力;在恢复划水阶段的高升力与背侧边缘涡强度的持续增加,以及因鳍表面倾斜而引起的水动力被分解到竖直方向的比重提升有关;胸鳍尾流场被一个三维双环涡结构所支配;当前的模拟为仿胸鳍推进建立了一个最优的斯特劳哈尔数St范围(在0.55附近),在此之后平均推力仍随St的增大而增加,而推进效率则表现出一个缓慢降低的趋势;当前后拍动与纵倾运动之间的相位差为90度时,胸鳍同时取得最佳的推力和效率。  相似文献