塔里木西缘明尧勒背斜的弯滑褶皱作用与活动弯滑断层陡坎   总被引：1，自引：1，他引：0       下载免费PDF全文

杨晓东  陈杰  李涛  李文巧  刘浪涛  杨会丽 《地震地质》2014,36(1):14-27

塔里木西缘明尧勒活动背斜两翼河流阶地面上多处发育活动弯滑断层陡坎。这些断坎主要分布在活动轴面附近较陡的等斜岩层(地层倾角分别为74°~89°、18°~20°和45°~60°)一翼,往往成排发育在距活动轴面50~1 200m范围内,宽90~1 000m,长40~950m,随着离活动轴面的距离加大弯滑断层陡坎规模渐小。同一阶地面上发育的弯滑断层陡坎几乎以等间距或间距倍数关系产出。这些断坎走向与下伏基岩地层走向一致,基岩地层大多为中-厚层块状砂岩或粉砂岩互层,岩层间力学性质差异较小。明尧勒背斜南翼克孜勒苏河北岸T3阶地面废弃以来,单条弯滑断层的地表最大缩短速率为0.31mm/a,地表最大抬升速率为0.34mm/a。这些弯滑断层的活动具有重复性和新生性。  相似文献   

滑脱褶皱陡坎的变形特征和运动学模型:以帕米尔-南天山前陆地区明尧勒背斜为例          下载免费PDF全文

李涛  陈杰  肖伟鹏 《地震地质》2014,36(3)

褶皱陡坎是褶皱变形过程中形成的地貌陡坎,是近期发现的一种不同于断层陡坎的构造作用形成的陡坎状地貌。在缺少地震反射剖面等深部资料时,利用褶皱陡坎可对活动褶皱的变形特征和生长演化历史进行限定,但迄今为止有关研究较少。位于帕米尔-南天山前陆地区的明尧勒背斜为第四纪活动的滑脱褶皱。在背斜南翼的河流阶地上发育了一系列褶皱陡坎:在T2和T3b阶地上,褶皱陡坎的高度/宽度/坡度分别为16m/40m/25°和20m/50m/26°,陡坎位置与下伏基岩中向斜枢纽位置对应。通过对这些褶皱陡坎的分析,得出:1)这些褶皱陡坎是滑脱褶皱通过膝折带迁移机制形成的。2)褶皱陡坎形成初期,陡坎高度、宽度和坡度逐渐增大;当陡坎宽度达到枢纽带宽度2倍时,陡坎坡度将达到最大值;之后尽管陡坎高度和宽度逐渐增大,其坡度将保持恒定。3)褶皱陡坎吸收的缩短增量与陡坎高度和下伏地层倾角间存在定量几何关系。根据T2阶地上褶皱陡坎的高度约16m和暴露年龄约8ka,估算T2阶地面暴露以来明尧勒背斜南翼的缩短速率为~1.3mm/a。在上述分析基础上,还对比总结了滑脱褶皱陡坎和断弯褶皱陡坎的异同点。  相似文献   

Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)     

《Journal of Geodynamics》2014

Integrated geological, geodetic and marine geophysical data provide evidence of active deformation in south-western Sicily, in an area spatially coincident with the macroseismic zone of the destructive 1968 Belice earthquake sequence. Even though the sequence represents the strongest seismic event recorded in Western Sicily in historical times, focal solutions provided by different authors are inconclusive on possible faulting mechanism, which ranges from thrusting to transpression, and the seismogenic source is still undefined. Interferometric (DInSAR) observations reveal a differential ground motion on a SW–NE alignment between Campobello di Mazara and Castelvetrano (CCA), located just west of the maximum macroseismic sector. In addition, new GPS campaign-mode data acquired across the CCA alignment documents NW–SE contractional strain accumulation. Morphostructural analysis allowed to associate the alignment detected through geodetic measurements with a topographic offset of Pleistocene marine sediments. The on-land data were complemented by new high-resolution marine geophysical surveys, which indicate recent contraction on the offshore extension of the CCA alignment. The discovery of archaeological remains displaced by a thrust fault associated with the alignment provided the first likely surface evidence of coseismic and/or aseismic deformation related to a seismogenic source in the area. Results of the integrated study supports the contention that oblique thrusting and folding in response to NW–SE oriented contraction is still active. Although we are not able to associate the CCA alignment to the 1968 seismic sequence or to the historical earthquakes that destroyed the ancient Greek city of Selinunte, located on the nearby coastline, our result must be incorporated in the seismic hazard evaluation of this densely populated area of Sicily.  相似文献   

四川盆地熊坡背斜构造特征及其成因机制     

李敬波  李勇  赵国华  颜照坤  周荣军  郑立龙  闫亮  杨聿强 《现代地质》2014,28(4):761-771

基于地震剖面解释、数字高程模型、历史地震、测年数据及钻孔等资料,分析了四川盆地熊坡背斜的构造特征、运动学特征及其成因机制。结果显示：(1)熊坡背斜与蒲江-新津断裂空间展布上具有较强的一致性,表现出断层传播褶皱模型,变形显著,缩短量为7.2 km,缩短率约为30％;(2)熊坡背斜隆起于(1.0±0.2) MaB.P.之后,且中更新世早期及晚更新世曾发生过强烈活动,使背斜两侧第四系厚度产生明显差异;(3)蒲江-新津断裂现今地震活动明显且小震频繁,曾有Ms=5.0～5.9的地震历史记录;(4)来自龙门山与扬子克拉通的挤压应力以及断层-滑脱作用是形成熊坡背斜的主要应力机制。熊坡背斜并非均匀应力下连续变形的产物,而是由于断裂活动时发生快速抬升而形成的。  相似文献   

断层转折褶皱剪切裂缝发育模式探讨     

祖克威  曾联波  赵向原  刘国平 《地质力学学报》2014,20(1):16-24

围绕库车前陆盆地内某典型断层转折褶皱剖面,实测统计该剖面不同构造部位的剪切裂缝,分析断层转折褶皱中剪切裂缝的发育规律,进而建立断层转折褶皱剪切裂缝的发育模式。统计结果表明,研究区剪切裂缝有2种类型,一类是与岩层面高角度相交的高角度缝,广泛发育在构造各个部位;另一类是与层面近于平行的顺层裂缝,主要发育在断层面附近,并随岩层的变形,产状发生改变。远离断层面,剪切裂缝发育程度整体上呈减小趋势,下盘裂缝发育强度的减小大于上盘,上盘裂缝发育强度整体大于下盘。褶皱内层剪切裂缝较外层发育,褶皱两翼裂缝发育强度大于褶皱枢纽。断层产状的改变,会引起上盘运动状态的改变,使得在上盘活动轴面附近出现应力集中,局部剪切裂缝发育强度出现增大现象。断层转折褶皱剪切裂缝的发育模式可以分为3个阶段,断层形成前主要发育与层面高角度相交的区域性剪切裂缝;断层形成初期,断层面附近两盘牵引变形不明显,上盘穿过断坡下部破折点处活动轴面的部分会产生新的剪切裂缝,即与岩层高角度相交剪切缝和与断层面低角度相交剪切缝;牵引构造明显时,断层面附近两盘弯曲部位会产生顺层剪切裂缝,两翼的裂缝发育强度大于枢纽。   相似文献   

叠加褶皱研究进展综述   总被引：1，自引：0，他引：1  

陈龙  施炜 《地质力学学报》2014,20(4):455-468

叠加褶皱作为地壳构造变形中一种常见的地质现象, 对于确定多期变形和构造运动期次, 探讨构造演化历史以及内外生矿床的空间分布、形成与变形特征均有重要研究意义。在回顾叠加褶皱研究历史与近年来取得的主要进展基础上, 系统地总结了叠加褶皱几何学与运动学特征, 指出叠加褶皱主要有纵弯褶皱作用、横弯褶皱作用及剪切褶皱作用3种成因机制。在此基础上, 选取典型的叠加褶皱, 剖析了其构造样式及形成机制, 并探讨了叠加褶皱研究的难点与可行研究方法。   相似文献   

老挝万象省爬立山（PHaLek）铁矿床地质特征及成矿作用分析   总被引：3，自引：0，他引：3  

朱华平  范文玉  毛洪江  吴振波  高建华  刘书生 《吉林大学学报(地球科学版)》2014,44(5):1492-1501

爬立山铁矿床位于长山褶皱带北西端,是长山成矿带内与岩浆作用有关的一个大型铁矿床。根据野外地质观察及室内对含矿岩体、赋矿围岩和矿石开展的岩相学和地球化学研究发现：与成矿作用有关的花岗质岩石属钙碱系列准铝质的I型花岗岩,成岩的构造环境为火山弧。矿区内发育致密块状磁铁矿、孔洞状赤铁矿、砂砾土状铁矿等3种铁矿石。结合岩（矿）石微量元素分析,认为爬立山铁矿具有复合成矿作用特征,主要可分为3个成矿阶段：早期以与华力西期岩浆侵入作用有关的接触交代成矿作用为主,形成矽卡岩型磁铁矿;其后,在褶皱造山后形成的断陷盆地中,由于火山喷发（溢）作用形成孔洞状熔岩型赤铁矿;最后随着新生代地壳抬升,发生表生物理化学风化成矿作用,形成如今的砂砾土状型铁矿。  相似文献   

Three‐dimensional Evolutionary Models of the Qiongxi Structures,Southwestern Sichuan Basin,China: Evidence from Seismic Interpretation and Geomorphology   总被引：1，自引：1，他引：0  

JIA Qiupeng  JIA Dong  LUO Liang  CHEN Zhuxin  LI Yiquan  DENG Fei  SUN Shengsi  LI Haibin 《《地质学报》英文版》2009,83(2):372-385

Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic.  相似文献   

安徽省琅琊山铜矿床深部资源潜力分析及勘查          下载免费PDF全文

杨峰  邢善强 《地质找矿论丛》2009,24(3):217-221

通过矿山生产实践对控岩控矿构造的认识积累和矿区构造形迹的解析,结合CSAMT法测量所获得的异常,推断矿床岩体底部隐伏矿体的存在。经深部资源勘查项目的实施并得以验证,进而提出了下一步资源递进勘查的总体方向和目标。  相似文献   

西天山伊宁地块主褶皱幕鄯善运动的确立及地质意义   总被引：7，自引：0，他引：7  

李永军  杨高学  张天继  栾新东  王晓刚 《地球科学进展》2009,24(4):420-427

地层不整合接触是研究地质发展历史及鉴定地壳运动特征和运动时期的重要依据,主褶皱幕是一造山带多幕构造运动中起决定性作用和最为重要的一次构造运动。天山的构造运动幕次多且因地而异,前人认识多有分歧,也没有确立主褶皱幕。伊宁地块伊什基里克山一带上、下石炭统之间为角度不整合接触关系,在岩石组合、沉积环境、古生物地理区系、构造样式、区域大地构造背景等方面差异最为显著,凸显了鄯善运动对区内构造格架和盆山演化起到决定性的作用,因而是主褶皱幕。鄯善运动记录了西天山沟—弧—盆格局消亡,天山残余小洋盆终结,塔里木板块和准噶尔板块最终拼合在一起,形成了统一大陆的重要演化信息。  相似文献