首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
Geologic, geomorphic and seismologic data indicate that west of Lake Cachuma the Santa Ynez fault branches into several major W- and NW-trending splay faults. Two of the faults bracket the wedge-shaped Santa Maria basin. The most compelling evidence for the existence of these two faults is the fact that the Santa Maria basin is floored by Franciscan basement overlain only by Miocene and younger sedimentary rocks, whereas across the inferred traces of each of these faults, the adjacent terrains consist of Franciscan basement overlain by thick sequences of Early Tertiary strata, as well as by Miocene and younger rocks. The third splay fault strikes northwestward through the central Santa Maria basin. Narrow zones of tightly appressed, left-stepping en-echelon folds are locally adjacent to the faults along the south edge, and through the center of the basin. The geometrical arrangement of these folds is indicative of formation over buried sinistral wrench faults. Evidence for Holocene surface rupturing is lacking or nebulous at best, but epicenters of damaging historical earthquakes are spatially, and by inference, genetically related to the central Santa Maria basin faults, indicating that they comprise the presently active strands among the several splay faults.  相似文献   

2.
A 100 km long balanced structural transect is presented for the Patagonian Andes at 50° S Latitude. The area studied is characterized by a fold belt in the eastern Andean foothills and basement-involved thrusts in a western-basement thrust zone. The basement thrust zone exposes pre-Jurassic, polydeformed sedimentary and layered metamorphic rocks emplaced over Lower Cretaceous rocks above an E-vergent thrust located at the western end of the fold belt.

The fold belt is developed in a 3 km thick deformed Cretaceous–Paleogene sedimentary cover with few basement outcrops and scarce calc-alkaline magmatism. Cover structures related to shallow décollements have a N-S to NW-SE strike, with fold wavelengths from 1100 to 370 m in the east to 20 to 40 m in the west. However, long-wavelength basement-involved structures related to deeper décollements have a dominant N-S to NE-SW trend along the eastern and western parts of the fold belt. Field evidence showing different degrees of inversion of N-S–trending normal faults suggests that the orientation of the Cenozoic compressive basement structures was inherited partially from the original geometry of Mesozoic normal faults.

The deformation propagated toward the foreland in at least two events of deformation. The effects of Paleogene (Eocene?) compressive episode are observed in the western fold belt and a Neogene (Late Miocene) compressive episode is present in the eastern fold belt. Basement-involved structures typically refold older cover structures, producing a mixed thick and thin-skinned structural style. By retrodeforming a regional balanced cross section in the fold belt, a minimum late Miocene shortening of 35 km (26%) was calculated.  相似文献   

3.
An intracratonic thrust belt, developed during the early Carboniferous in central Australia, deformed the Amadeus Basin and its basement, the Arunta Block. This belt is characterized by a marked structural asymmetry (vergence) and by the deposition of a thick molasse basin on the foreland. A review of existing field data shows that décollement tectonics produced folding, thrusting, faulting and back-faulting of the sedimentary sequence. Thin-skinned tectonics extend into the basement to produce recumbent folds and têtes plongeantes of nappe structures rooted in steeply dipping mylonite zones of greenschist to amphibolite grade. Minimum horizontal shortening displacements are 50–100 km resulting in a 50–70% contraction of the upper part of the basement. The structures and shortening are best explained by a crustal duplex, characterized by a crustal-scale thrust system, i.e. a sole thrust and imbricate faults, responsible for an isostatic bending of the underthrust slab. The observed Bouguer anomaly profiles support this crustal model. The dynamic evolution of this thrust belt on the scale of the crust is of thin-skin type.  相似文献   

4.
焉耆盆地和静北部地区发育一个现今地貌上的小型背驮盆地。新生代地层中砾岩砾石成分稳定,以变质岩和沉积岩成分居多,岩浆岩很少;砂岩成熟度普遍低,长石和石英含量少,岩屑含量居多,砂岩成熟度从盆地早期渐新统—中新统的玛萨盖特组到上新统—更新统安吉然组下降。该盆地内部及其周缘地区新生代地层古水流方向主要向南,显示物源是北部的南天山地区,直至更新世时期该背驮盆地并未单独发育,而是焉耆盆地北部的一部分。由于天山地区的侧向扩展作用,更新世以来本区形成了典型的逆冲断裂带,北部的逆冲断层使中泥盆统逆冲到安吉然组之上,中部的一条逆冲断裂使下伏的中泥盆统和花岗岩体抬升,形成了现今的地貌;南部的逆冲断层作用在安吉然组内形成了南陡北缓的断层相关褶皱。和静地区的新生代变形是由北向南进行的,具有西强东弱的特点,西部地区的构造缩短率大于东部地区。  相似文献   

5.
库车再生前陆盆地冲断构造楔特征   总被引:60,自引:4,他引:56  
库车再生前陆盆地冲断构造楔由一系列向南运动的逆冲断层和相关褶皱组成。冲断楔的北部以断层转折褶皱、断层传播褶皱、双重逆冲构造为主。断层楔的前缘发育了很好的滑脱膝折背斜,全为盲断层控制,形成隐蔽式前锋。冲断层的就位从中新世开始,自北向南迁移,前锋的构造形成在第四纪。造成逆冲断层的地壳水平缩短作用速度在中新世较慢,平均为0.355mm/a,上新世中期达0.82mm/a,而到上新世晚期和第四纪速度增大了约一个数量级,达到1.29-3mm/a。  相似文献   

6.
川东南地区构造变形复杂,二叠系和志留系含有丰富的页岩气资源。依据岩性和地震资料的解释,寒武系膏盐层与中-下三叠统膏盐层对构造变形有重要控制作用,多数断层沿膏盐层滑脱。研究区包括盆内和盆缘两部分,盆内发育形态对称的盖层滑脱式褶皱;盆缘发育基底卷入式褶皱冲断构造,分为山前推覆带和山前转换带,前者发育高陡的三角楔构造,后者由冲断带、褶皱带和斜坡带组成。构造演化分析表明:晚侏罗世齐岳山断层开始发育,盆内地层发生挠曲变形;白垩纪盆缘形成三角楔构造,盆内主要构造和断裂已经发育;新生代齐岳山褶皱隆升,盆内寒武系之上沉积盖层褶皱形成多个背斜和向斜。山前推覆带构造高陡、变形强烈,页岩气保存条件差;山前转换带构造变形程度适中,其褶皱带背斜完整,页岩气保存条件好;盆内中-下三叠统膏盐层封盖性好,埋深适中的背斜为页岩气有利勘探目标区。   相似文献   

7.
渭河盆地结构特征及演化研究   总被引:2,自引:1,他引:1  
渭河盆地是位于秦岭造山带和鄂尔多斯盆地之间的断陷盆地。渭河盆地的形成时间以及基底构成目前仍存在着争议。近几年来,对于渭河盆地天然气类型、形成机制、成藏条件、资源潜力以及盆地结构构造等方面的研究取得了很大进展,为解决以上争议提供了进一步的资料。根据盆地的钻探资料和物化探新成果,发现渭河盆地是由固市凹陷、西安凹陷、泾河鼻隆、宝鸡凸起、骊山凸起、咸阳斜坡带和富平-蒲城斜坡带组成,并具有新生代、中生代-古生代复式盖层和两盆一鼻两凸两斜坡镶嵌复合结构特征;渭河盆地新生代之下的中生代-古生代盖层为:西部宝鸡凸起为古生界地层,中部西安凹陷和咸阳斜坡带为中生代地层,东北部富平-蒲城斜坡带基底为奥陶系地层,东南部固市凹陷基底为晚古生代地层;渭河盆地与鄂尔多斯盆地具有相同的基底和相似的盖层;太要断裂(约1800 Ma)形成,为渭河盆地形成奠定了构造基础,奥陶世马家沟末加里东运动及渭北隆起南缘同生逆冲断裂形成,标志着渭河盆地独立演化的开始,主沉降期为中生代-新生代;结合已有研究,给出了渭河盆地的基底模型和渭河盆地的演化模式。   相似文献   

8.
循化-化隆盆地新生代沉积及盆地基底和周缘山系磷灰石裂变径迹年代学分析揭示了青藏高原东北缘晚白垩世以来经历过3期隆升剥露事件: (1)盆地基底及拉脊山和西秦岭北缘构造带磷灰石裂变径迹年龄分析普遍记录了晚白垩世-始新世中期相对快速的区域性的隆升剥露事件, 西秦岭北缘快速抬升的起始时间为84Ma, 受控于向北的逆冲抬升; 向北到循化-化隆盆地中部的拉目峡抬升的起始时间为69Ma; 更北的拉脊山一带快速抬升期主要为40~50Ma, 从而反映晚白垩世-始新世中期的快速抬升由南向北逐渐扩展.这一期构造隆升事件导致循化-化隆盆地和临夏盆地缺失了北部西宁-民和盆地古近纪所具有的西宁群沉积.隆升剥露结束于31Ma左右, 此时化隆-循化盆地向东与同时期的临夏盆地相连为一个统一的大型西秦岭山前盆地, 两者具有相同的构造、沉积演化史, 因此循化-化隆盆地他拉组底部地层年龄最老不会超过临夏盆地最老地层的古地磁年龄, 即29Ma.(2)渐新世晚期约26Ma拉脊山开始双向逆冲隆升, 并可能延续到中新世早期约21Ma, 隆升作用使循化-化隆盆地成为挟持于拉脊山逆冲带和西秦岭构造带之间的山前挤压型前陆盆地, 循化-化隆盆地开始大规模沉积巨厚的他拉组冲积扇相粗碎屑岩.(3)通过循化-化隆盆地咸水河组和临夏组的沉积相分析、古流方向和砾石成分分析, 揭示出拉脊山构造带在中新世8Ma左右发生的最大规模的双向逆冲隆升事件, 这次事件直接导致循化-化隆盆地由前陆挤压盆地转变为山间盆地, 形成现今青藏高原东北缘的盆山地貌基本格局.   相似文献   

9.
藏北改则新生代早期逆冲推覆构造系统   总被引:2,自引:0,他引:2  
藏北改则及邻区新生代早期发育大型逆冲推覆构造系统,由不同方向的逆冲断层、不同时代的构造岩片、不同规模的飞来峰和构造窗、不同类型的褶皱构造组成。羌塘中部发育羌中薄皮推覆构造,石炭系板岩和二叠系白云质灰岩自北向南逆冲推覆于上白垩统与古近系红层之上,形成大型逆冲岩席和弧形逆冲断层,原地系统古近纪红层下伏三叠系—侏罗系海相烃源岩。羌塘南部发育南羌塘薄皮推覆构造,导致班公—怒江蛇绿岩、三叠系—侏罗系海相地层及侏罗纪混杂岩自北向南逆冲推覆于古近纪红层与下白垩统海相沉积岩层之上,形成三条蛇绿岩片带、大量飞来峰和厚度较大的构造片岩。中新世早期火山岩层和湖相沉积呈角度不整合覆盖逆冲断层、褶皱构造和逆冲岩席,不整合面上覆火山岩年龄为23.7~19.1Ma,指示中新世早期改则及邻区基本结束了强烈逆冲推覆构造运动。估算羌中逆冲推覆构造的推覆距离约100~115km,南羌塘逆冲推覆构造的推覆距离约82~110km;新生代早期改则逆冲推覆构造系统近南北方向逆冲推覆总距离为182~225km,对应地壳缩短率为(50.3±2.7)%。  相似文献   

10.
在阿拉善地块东缘发现新生代中新世挤压构造,形成近SN或NE-SW走向的逆冲断层及卷入新生代地层的褶皱.其形成背景关系到阿拉善地块新生代的变形特征以及与青藏高原扩展的关系.为了进一步探讨阿拉善地块东缘的挤压构造是否受青藏高原扩展控制,为青藏高原北缘新生代扩展过程的研究提供资料,通过详细地质填图、区域地质调查与对比方法,确定了这些挤压构造的几何样式以及运动学特征,结合断层滑动矢量,恢复出变形时的古应力场.室内外的分析表明,形成这些挤压构造的最大主应力方位为NW-SE或近EW向,结合盆地地震反射资料、卷入构造的地层,推测变形的时代是中新世中晚期.这期变形的动力可能是阿拉善地块受到青藏高原北缘的挤压向东运动所致.同时在阿拉善地块向东运动的过程中,其内部发育的早期东西向构造带发生右行走滑,和阿拉善东缘的挤压构造一同调节地块的变形.晚中新世之后,高原东北缘最大主应力方位发生顺时针旋转,阿拉善东缘挤压构造被后期构造叠加.   相似文献   

11.
库车新生代构造性质和变形时间   总被引:126,自引:6,他引:120  
库车构造位于南天山古生代碰撞造山带之南,为塔里木盆地最北的一个构造带。它自北而南可分为边缘逆冲( 隐伏构造楔) 、斯的克背斜带、北部线性背斜带、拜城盆地、南部背斜带。每个背斜带又包含有若干逆冲断层相关褶皱,它们是断层转折褶皱、断层传播褶皱、滑脱褶皱、断层传播 滑脱混生褶皱、双重逆冲构造、突发构造、三角带构造。底部逆冲断层向南变浅,堆叠逆冲岩席向南变薄,总体上形成一个向南的逆冲构造楔。逆冲断层在斯的克背斜带侵位最早(25 Ma) ,在北部线性背斜带为169 Ma,拜城盆地中的大宛其背斜为36 Ma,南部背斜带为53 Ma( 北部) 和18 Ma( 南部) ,变形作用向南变新。库车构造是印 藏板块碰撞的内陆构造响应,是二叠纪前陆盆地复活而成的再生前陆盆地变形带  相似文献   

12.
杨斌 《地质与勘探》2014,50(Z1):1314-1319
藏南古堆地区具南北分带特征。北部地区靠达拉岩体,受也拉香波穹窿影响,断层以倾向南的正断层为主,地层呈多期次挤压褶皱形态,且出现呈楔形构造夹片出露的红柱石板岩、石榴石片岩等变质核杂岩地层;中部地区断层、褶皱较发育,褶皱呈紧闭的层间同斜褶皱,断层以倾向北的叠瓦状脆-韧性逆冲断层为主;南部地区为相对稳定区,该区地层相对较完整,褶皱以宽缓向斜形式出现,且越往南越宽缓。这一构造样式是印度板块与欧亚板块碰撞之后,在喜马拉雅造山运动影响及后期伸展作用的背景之下,由北向南的挤压推覆的结果,总体上它是一套挤压褶皱~推覆逆冲断层的组合,呈叠瓦状展布的隆子断裂是主推覆断层。  相似文献   

13.
龙门山冲断带北段前锋带新生代构造变形   总被引:3,自引:0,他引:3  
陈竹新  李本亮  贾东  雷永良 《地质学报》2008,82(9):1178-1185
龙门山北段前锋构造的地震剖面解释和前缘盆地内沉积地层的磁组构研究表明前锋构造中发育两期构造挤压作用,即整体强烈的晚三叠世变形和由北向南逐渐减弱的弱新生代构造变形。受这两期构造挤压作用的控制,龙门山北段前锋构造中发育上、下两套构造层,地表构造为晚三叠世时期形成,而深部隐伏构造则形成于新生代。北部的矿山梁和天井山构造几何学上表现为一个双重构造,浅层是一个晚三叠世形成的断层转折褶皱;深层是新生代形成的多个逆冲岩片叠置所构成的隐伏堆垛背斜;南部的青林口和中坝构造主体表现为叠瓦状逆冲,前锋构造是断层转折褶皱和断层传播褶皱。新生代构造冲断位移量以及造成早期构造抬升由北向南逐渐减小,反映新生代变形强度由北向南的减弱。磁组构研究表明新生代变形从龙门山冲断带边缘到盆地内部,磁组构从铅笔状磁组构到初始变形磁组构并逐渐过渡到沉积磁组构。由南向北磁组构由初始变形磁组构转变为铅笔状磁组构,说明应变越来越强,从而进一步证明了龙门山前锋新生代构造的弱变形作用和变形强度的北强南弱分布特征。  相似文献   

14.
黄骅盆地南部前第三系基底中的逆冲构造   总被引:12,自引:0,他引:12  
黄骅盆地南部前第三系构造层中广泛发育有逆冲构造.其中西部的逆冲构造带以逆冲堆叠背形构造和逆冲叠瓦扇构造为主, 中部以楔冲双重构造和低角度盲冲或顺层滑脱构造为主, 东部以高角度板状逆冲叠瓦构造为主.这些逆冲构造带都表现为由SE向NW-MNW方向的逆冲, 而且由构造样式推测的拆离滑脱深度是由西向东逐渐加深, 表明在深层可能有一条向南东倾斜的拆离断层将它们连锁在一起, 构成统一的逆冲构造系统.从卷入逆冲构造的地层的地质时代推测, 逆冲构造主要是在早—中三叠世盆地发育之后、侏罗—白垩纪盆地形成之前形成的, 并在早—中侏罗世盆地发育过程中又有进一步活动.逆冲构造形成后又受到中—新生代时期的伸展构造和走滑构造的叠加和改造.控制黄骅盆地老第三纪伸展盆地的形成和演化的沧东断层的某些地段, 在前第三纪时期曾经是一条逆冲断层.   相似文献   

15.
柴达木盆地新生代不同层次构造特征   总被引:8,自引:1,他引:8       下载免费PDF全文
应用柴达木盆地地震、非地震资料进行综合解释研究发现,新生代盆地深、浅层构造存在较大差异,盆地沉积在不同时期受到不同构造格局的控制。古近系受近东西向构造控制,新近系受北西向构造控制,显示了柴达木盆地新生代为不同时期受不同方向构造控制的大型叠合盆地。盆地地层深、浅层构造变形特征不同,深层表现为陡倾的逆冲断裂构造,以断块构造为主要特征;中浅层表现为滑脱褶皱与滑脱断裂构造;地表在背斜核部发育斜列展布的正断层构造。盆地经历了多旋回沉积和多方式的后期改造,不同的构造组合形成了不同的储油气构造模式,认识这一点对于盆地深层的油气勘探,特别是寻找隐蔽油气藏具有重要意义。  相似文献   

16.
Geologic mapping and U–Pb detrital zircon geochronologic studies of (meta)sedimentary rocks in the Damxung area (∼90 km north of Lhasa) of the southern Lhasa terrane in Tibet provide new insights into the history of deformation and clastic sedimentation prior to late Cenozoic extension. Cretaceous nonmarine clastic rocks ∼10 km southeast of Damxung are exposed as structural windows in the footwall of a thrust fault (the Damxung thrust) that carries Paleozoic strata in the hanging wall. To the north of Damxung in the southern part of the northern Nyainqentanglha Range (NNQTL), metaclastic rocks of previously inferred Paleozoic age are shown to range in depositional age from Late Cretaceous to Eocene. The metaclastic rocks regionally dip southward and are interpreted to have been structurally buried in the footwall of the Damxung thrust prior to being tectonized during late Cenozoic transtension. Along the northern flank of the NNQTL, Lower Eocene syncontractional redbeds were deposited in a triangle zone structural setting. All detrital zircon samples of Cretaceous–Eocene strata in the Damxung area include Early Cretaceous grains that were likely sourced from the Gangdese arc to the south. We suggest that the that newly recognized Late Cretaceous to Early Eocene (meta)clastic deposits and thrust faults represent the frontal and youngest part of a northward directed and propagating Gangdese retroarc thrust belt and foreland basin system that led to significant crustal thickening and elevation gain in southern Tibet prior to India-Asian collision.  相似文献   

17.
雪峰山西部中生代厚皮逆冲推覆构造样式与变形特征研究   总被引:2,自引:0,他引:2  
雪峰山厚皮逆冲推覆构造带位于扬子地块东南缘,由南向北,主构造线走向由北北东向渐变为北东东向,形成向北西突出的弧形。构造带内基底新元古界板溪群大面积出露,这些基底出露的原因和构造方式是华南中生代大地构造分析的核心问题之一。以野外构造解析为基础,结合相关地球物理资料解释,对雪峰山西部逆冲推覆构造的构造样式与变形序列进行了系统的解析。结果表明,雪峰山构造带从印支期开始发育由南东向北西的大规模的逆冲推覆构造,逆冲断层在近地表向南东陡倾,向下逐渐收敛于基底内的滑脱断层之上。基底新元古界板溪群及早古生界均卷入了推覆构造,同时逆冲覆盖于中生代地层之上,形成厚皮构造,并造成了基底板溪群的大面积出露。  相似文献   

18.
The Talaud Islands lie at the northern margin of the collision zone between the Sangihe and Halmahera island arc systems. Rock units on Talaud are Neogene marine strata, basalt and andesite, tectonic mélange, and ophiolite. The units are exposed in N–S trending belts that are commonly separated by faults. The marine strata consist of tuffaceous siltstone, sandstone, shale and marl. They are strongly deformed by west-verging folds with wavelengths of 20–500 m. Volcanic rocks of island arc affinity are exposed on the east coast of Karakelang Island and appear to be interbedded with the lowermost marine strata. Tectonic mélanges contain blocks of serpentinite, gabbro, basalt, red middle Eocene chert and limestone, and greywacke turbidites. The blocks range in length from a few millimetres to hundreds of metres, and are enclosed in a scaly clay matrix. Several mappable slabs of ophiolite are separated by Tertiary strata or mélange. The dismembered ophiolites consist of serpentized peridotite, gabbro, spilites and cherts. Locally, the mélanges and ophiolites are thrust over the younger sedimentary rocks along east-dipping faults. The dominant eastward dips of mélange foliation, the westward vergence of structures in the Neogene strata, the Eocene ages of the cherts, and the Miocene age of the strata overlying the ophiolite slabs suggest that the ophiolites are pieces of Eocene or older oceanic crust (derived from a mid-ocean ridge or back-arc basin) and upper mantle that were emplaced as thrust slices into the lower slope of a west-facing arc during the Miocene and have been uplifted during arc—arc collision.  相似文献   

19.
冀西北尚义盆地对晚侏罗世构造活动的沉积响应   总被引:2,自引:1,他引:1       下载免费PDF全文
尚义盆地位于走向近东西的中生代燕山冲断带前缘盆地群的西段,在晚侏罗世土城子时期堆积了大量的粗碎屑。盆地中土城子组沉积相变明显,自北向南从粗砾质变为粉砂质沉积,具比较典型的非对称相带分布特征。土城子早一中期,从北向南总体上形成砾质冲积扇(包括泥石流)-辫状河流-洪泛平原或干化湖泊等古环境布局。晚期则以砂砾质辫状河流沉积为主,可能夹有发育大型风成交错层理的砂质沙丘沉积。土城子组碎屑成分以变质岩和花岗质岩石为主.物源主要来自盆地北侧的"内蒙地轴",沉积充填具有同构造砾岩的性质。尚义盆地北缘发育一系列呈叠瓦状排列的逆冲断裂。断裂与盆地耦合关系的初步分析显示.北缘逆冲断裂的构造载荷是控制尚义盆地形成和演化的主要因素。靠近北部冲断带一侧沉积相序的中—下部具有向上变粗的特点.可能指示了土城子组沉积受前进式的冲断载荷和岩石圈挠曲控制的过程。根据尚义盆地与其北侧相关断裂的空间配置、沉积碎屑北粗南细的变化、盆地横断面北厚南薄的楔状体特征等分析.盆地属于陆内的前陆式盆地,推测是在自北向南的近水平挤压构造背景下形成的.  相似文献   

20.
北黄海盆地构造几何学研究新进展   总被引:6,自引:0,他引:6  
北黄海盆地是发育于胶辽隆起背景之上的中、新生代沉积盆地。研究表明,北黄海中、新生代沉积盆地的基底由古生界沉积岩层和前寒武纪变质岩系等组成,盆地不同程度地发育于中新生代下构造层(J3-K1)、中构造层(E2-E3)和上构造层(N).从油气资源和中、新生代地层发育情况出发,将北黄海海域划分为辽东-海洋岛隆起区、北黄海盆地和胶北-刘公岛隆起区3个一级构造单元。其中北黄海盆地包括6个二级构造单元和24个三级构造单元;盆地内褶皱、断裂构造十分发育,褶皱构造可划分为区域挤压型、局部伴生型和披覆型3类,断裂构造主要可见近EW-NE向、NW向和NNE向3组,其中近EW-NE向和NNE向断裂比较发育,控制着盆地隆、坳分布格局和沉积特征。   相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号