共查询到19条相似文献，搜索用时 187 毫秒
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板内造陆变形以平行不整合为标志，它是一个容易失稳的界面，后期构造变动中常常转化成拆离面。中浅构造层次形成脆性拆离断层（拆离带）；中深构造层次则形成韧性剪切断层（韧性剪切带）。板内造陆变形及其后期演化改善了储集岩性能，影响了油气运移和聚集。后期转化还可以使油气重新运移，也可形成新的油气圈闭，同时深刻影响油气演化，有利于再次生油气。 相似文献
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庐山出露的变质核杂岩的构造层次具有典型的三层结构,即最上面的未变质沉积盖层、中间韧性流变层、核部的变质基底,其间分别以上剥离断层和拆离断层为分界线。上部沉积盖层以脆性变形为主,中间韧性流变层变形程度不一,但远离拆离带变质变形逐渐减弱,而核部的变质基底以强塑性变形为特征。对变质核杂岩南北两条地质剖面的分析,得到三个构造层次的岩石变质变形及岩性变化特征。区域动力学分析反映变质核杂岩东部原拆离带在五里正断层附近。拆离带中多硅白云母压力计得出的变质压力为0.6~1.1 GPa;锆石U-Pb年龄测试得到变质核杂岩的隆升时代为早白垩世。 相似文献
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盆岭省科迪勒拉山变质核杂岩(MCC)中,分别与区域拉伸线理与擦痕有关的第三纪韧性糜梭岩化和碎裂岩化变形,成为水平拆离断层的特征。在Raft Yiuer,Grouse Gre ek和Albion山(犹他洲的西北部),一个主要的拆离断层将前寒武纪结晶基底从遭受强烈脆性变形和断裂作用的古生代岩石组成的断层上盘中分离出来。在拆离断层的下面,底板岩石受到糜棱岩化变形作用影响是大规模正剪切带的特征。为了表示断层下盘韧性变形作用的性质、运动历史和时间等特征,必须从事中型构造、有限应变、显微构造、石英C-轴组构以及~(39)Ar/~(40)Ar同位素年代学研究。我们提出:(1)区境性东西向拉伸线理代表剪切滑移的方向;(2)有限应变分 相似文献
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北喜马拉雅穹隆带雅拉香波穹隆的构造组成和运动学特征 总被引：21，自引：0，他引：21
雅拉香波穹隆构造位于北喜马拉雅穹隆带,由上、下两个拆离断层分割成3个构造层。下拆离断层以韧性变形为主,其下的糜棱状片麻岩和花岗岩体形成穹隆核部即下构造层;上拆离断层以脆性变形为主,其上为低级变质的西藏沉积岩系及基性岩墙群(上构造层);千糜岩和糜棱状片岩构成上、下两拆离断层间的中构造层。穹隆构造内经历3期运动,第1和第2期的线理具有统一的北北西—南南东倾伏向,前者仅保存于局部下构造层,代表上盘向南南东的运动学特征,为早期构造变形,成因尚待查明;第2期为穹隆内主导线理,代表穹隆统一的上盘向北北西的运动。第3期低透入性线理向穹隆外侧倾伏,代表垮塌下滑运动。雅拉香波穹隆下构造层与高喜马拉雅岩系相似,下拆离断层为主拆离断层,中构造层可能为西藏沉积岩系底部经拆离作用形成,所以下拆离断层可能是分割高喜马拉雅结晶岩系与西藏沉积岩系的藏南拆离系在北喜马拉雅的出露。雅拉香波穹隆早期(距今14.5Ma±)可能经历了沿藏南拆离系的北北西向拆离,后期(距今13.5Ma±)因岩浆底辟和剥蚀反弹而发生穹隆作用。 相似文献
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内蒙古苏尼特左旗早白垩世宝德尔花岗岩伸展穹隆的确定及其地质意义 总被引：3，自引：1，他引：2
内蒙古宝德尔穹隆是发育在苏尼特左旗中蒙边境地区的不对称同构造伸展穹隆。该穹隆由内向外由核部早白垩世花岗岩、边缘韧性剪切带和脆性拆离断层组成,上盘为未变形的早二叠世花岗闪长岩、泥盆系片岩和早白垩世盆地,韧性剪切带和拆离断层仅发育在穹隆西南部。区域构造解析和显微构造分析表明,岩体侵位和韧性剪切带形成于同一构造应力场,指示上盘统一向NW方向剪切,变形程度由未变形的岩体核部向外侧逐渐增强,面理的形成与岩体的侵位和隆升过程密切相关。因此,该穹隆和东北亚其他岩浆穹隆相似,是不对称的花岗岩穹隆,反映了区域伸展拆离环境下侵位的同构造花岗岩穹隆的特点。 相似文献
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珠江口盆地新生代发育跨越浅水区至深水区、多类型的拆离断陷,其中浅水陆架区拆离断陷是探究拆离构造变形与沉积充填响应的重要窗口.基于地震资料和钻井资料详细解析,对恩平凹陷低角度拆离断层特征进行了研究,探讨了拆离构造变形的控制因素、变形过程和沉积充填响应机制.研究表明,恩平凹陷低角度边界正断层为壳间拆离断层,长度约50 km,倾角平均17.5°,断面最深达中下地壳,裂陷期经历了中低角度到低角度的转变.拆离断层形成于中生代先存逆冲断层基础之上,与中下地壳韧性剪切穹隆和边界调节性走滑断裂相伴生,联合控制形成均衡深拆离、前展式宽拆离和迁移型复式拆离3种凹陷结构类型.垂向上可划分出三期裂陷幕,因差异构造变形而具有不同的沉积充填响应:（1）早文昌期均一裂陷幕,快速的裂陷沉降发育于先存逆冲断层弱面,形成具厚层中深湖的均一窄深箕状半地堑;（2）晚文昌期拆离伸展幕,凹陷受差异构造变形而发育成东、西沉积充填差异化的宽浅断陷,西部韧性剪切穹隆弱隆升与边界走滑断层强走滑控制了恩平17洼自迁移型中深湖和大型辫状河三角洲-重力流沉积,而东部韧性剪切穹隆强隆升控制了恩平12-18洼沉积中心跳跃式异迁移的沉积充填,过渡带发育大型走向斜坡扇三角洲;（3）恩平期拆离-断拗联控幕,构造变形由简单剪切向纯剪切转变,沉积向外流水系主导的浅水辫状河三角洲-浅湖相充填转变.低角度拆离断陷具有与高角度脆性断陷不同的构造变形和沉积充填响应,烃源岩与砂岩储层的时空分布非均质性强.研究成果对恩平凹陷的烃源岩和深部储层预测,以及南海北部陆缘同类拆离断陷的构造-沉积充填研究具有良好的指导意义. 相似文献
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庐山变质核杂岩具有典型的3层结构。拆离带是核部隆升过程中盖层滑脱、剪切变形而形成的,该拆离面是在北东向褶皱基础上叠加杂岩核部隆升作用而形成的波状起伏面。拆离带在核部以西发育倾向西向、南西向、北西向的面理和矿物生长线理,显示向西滑脱形成剪切拉伸变形的特征。拆离带岩石以糜棱岩和构造片岩为主,辅以碎裂岩和构造角砾岩。岩石变形特征表明其既具有韧性变形,也具有脆-韧性变形及脆性变形的特点。核部隆升引起的拆离变形作用,不仅形成了拆离带,还影响了拆离带以上盖层岩石,形成一个由拆离带向上由强变弱的变形域。这种规律性递变现象使庐山变质核杂岩具有垂向变形分层、水平变形分带的特点。拆离带中角闪石-斜长石矿物对计算得出的变质温度为653 ℃～694 ℃,压力为0.56～0.67 GPa。 相似文献
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医巫闾山韧性剪切拆离带位于华北克拉通北缘,为一走向NE、倾向WNW的低角度正断层系,由下盘的韧性剪切带(糜棱岩带)、未变形中生代的花岗岩体;脆性拆离断层面及上盘未变质的沉积岩系组成。以拆离断层带下盘韧性剪切带内糜棱岩长石碎斑为标志体的三维有限应变测量显示,应变主轴X轴伸长,Y轴不变,Z轴缩短。以极莫尔圆法估算拆离带内糜棱岩的运动学涡度值介于0.61到0.96,平均为0.80(涡度值是无量纲数),表明医巫闾山韧性剪切拆离带形成机制为以简单剪切为主的一般剪切作用。结合三维有限应变测量,医巫闾山韧性剪切拆离带为一加长减薄型剪切带。以有限应变测量与运动学涡度估算为基础,初步估算了该韧性剪切拆离带的韧性减薄量沿剪切拆离方向,减薄量从10%增加到40%,且减薄量与应变强度正相关、与运动学涡度负相关。 相似文献
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辽西医巫闾山变质核杂岩构造系统及其对金矿的控制 总被引：6，自引：0，他引：6
医巫闾山变质核杂岩形成于白垩纪，属对称型变质核杂岩，中心为晚燕山期的医巫闾山二长花岗岩体，周围是代表地壳深部变形特点的太古宇变质岩组成的变质核。变质核北面和东面以拆离断层与盖层下部中元古界相接触，西面以阜新盆地东南缘边界正断层与白垩纪脆性变形碎屑岩相邻。在横剖面上变质核杂岩构造系统中的组合较齐全，且不同的构造带、构造部位对成矿和控矿作用不同，可分为：（1）产于拆离断层中深层次韧性流变层内的矿床——排山楼金矿；（2）产于拆离断层中浅层次韧性流变层内的矿床——大板金矿；（3）产于盖层下部韧-脆性构造层中的矿床——大樱桃沟金矿；（4）产于盖层上部脆性构造层中的矿床——五家子金矿。显示了变质核杂岩构造系统对该区金矿的控制作用。 相似文献
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Mark Coleman Renelle Dubosq David A. Schneider Bernhard Grasemann Konstantinos Soukis 《地学学报》2019,31(3):220-233
The Lavrion district of the Attica Peninsula, Greece, exposes the West Cycladic Detachment System (WCDS), a low‐angle crustal‐scale extensional fault system separating tectonostratigraphic units of the Cycladic Blueschist Unit. New multiple single‐grain fusion and step‐heated white mica 40Ar/39Ar ages integrated with existing (U–Th)/He ages and independent paleothermometry resolves a syn‐ to post‐orogenic deformation history. A structurally higher unit records Oligocene greenschist facies deformation that evolved into brittle conditions by the middle Miocene, and shares a similar history to Serifos at the southern end of the detachment system. The structurally lowest unit remained ductile until the late Miocene, preserving pervasive post‐orogenic structures, similar to along‐strike structures at the centre, deepest part of the fault. The similarities of structural styles and the timing of deformation across > 150 km of strike length of the detachment system indicates tens of kilometers of offset and extraordinary potential for correlating observations along Cycladic‐style detachment systems. 相似文献
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Structural Traps in Detachment Folds: a Case Study from the ‘Comb- and Trough-like’ Deformation Zone/s, East Sichuan, China 总被引：1，自引：0，他引：1
WANG Zongxiu ZHANG Jin LI Tao ZHOU Xingui MA Zongjin TANG Liangjie XIAO Weifeng YAN Xili 《《地质学报》英文版》2012,86(4):828-841
Detachment structures occur widely in the crust, and it is the commonest and most important deformation type developed in the region between orogenic belts and basins. The ‘comb-like’ and ‘tough-like’ fold belts in eastern Sichuan are caused by multi-layer detachment. The duplex structure is the most important deformation style in the region, exhibiting different characteristics from typical detachment structures. Different deformation styles, scales, and shortenings resulting from independent deformations of various detachment systems would lead to the phenomenon whereby most of the topographical heights in the region do not correspond to the structural heights in depth. Based on systematic structural analysis and combined with practical oil/gas prospecting, four types of structural traps are described from eastern Sichuan Province, which are: detachment and thrust trap; detachment folding trap; fault-flat blocking trap; and detachment layer trap. Meticulous studies on the deformation and distribution of detachment layers in the eastern Sichuan Province will contribute to oil/gas prospecting and selection of potential regions of marine-origin oil/gas prospecting in South China. 相似文献
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赣北地区属扬子准地台的一个组成部分,其地台盖层中的滑脱断裂与滑脱褶皱紧密伴生,共同构成滑脱构造。滑脱断裂沿地台盖层中的软弱面、润滑层发育。滑脱断裂的总体产状是后缘倾角较缓,向前缘逐渐变陡至倒转;在平面上与地层走向一致,方向变化较大,因地而异、各不相同。滑脱断裂的构造样式,以短轴背形、向形构造为主,另有穹窿构造、滑来峰构造、滑覆窗构造。滑脱断裂是良好的内生热液矿床的储矿构造;滑脱断裂形成于中生代,大多己褶皱变形,工程地质条件良好。 相似文献
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南海北部珠江口盆地中段伸展构造模型及其动力学 总被引：1，自引：0，他引：1
位于南海北部大陆边缘上的珠江口盆地发育NNE向、NE向、NW向、近EW向等多组基底断裂,盆地结构复杂,并表现出明显的时空差异性。本文基于珠江口盆地中段地震资料解释的构造样式的变化推断地壳中存在一条向南缓倾斜、呈坡坪式形态的拆离断层,古近系构造属于这条拆离断层上盘的伸展构造系统。北部的西江凹陷属于拆离断层伸展构造系统的头部,凹陷边界正断层铲式断层面形态向深层延伸并收敛在拆离断层面上,凹陷表现为半地堑“断陷”样式;中部的番禺低隆起对应于拆离断层的低角度断坪部位,拆离断层上盘断块的伸展位移导致两侧的恩平组超覆在低隆起上;南部的白云凹陷位于拆离断层的深部断坡部位,充填的文昌组和恩平组表现为“断坳”或“坳断”样式;南部隆起位于拆离断层深部断坪部位,其上盘发育的分支断层控制着荔湾凹陷古近系、新近系的发育并使之表现为复杂的断陷断坳构造样式。该模型强调拆离断层上盘与下盘、不同地壳结构层均发生不同程度的伸展变形,且伸展变形方式、应变量等存在时空差异,而拆离断层正是不同构造单元、不同地壳构造层之间的调节性构造面。总体上,拆离断层上盘以脆性伸展构造变形为主,分支断层控制不同构造单元古近纪的构造演化,下盘则是以韧性伸展变形为主,并拖曳上盘发生不均一的伸展应变;西江凹陷的伸展应变量大于拆离断层下盘的伸展应变量,白云凹陷的伸展应变量则小于拆离断层下盘的伸展应变量。以西江凹陷北部边缘的NE向铲式正断层为头部的拆离断层控制了文昌组沉积,但在恩平组沉积期被近EW向高角度正断层切割破坏而被遗弃,拆离断层系统的头部由西江凹陷北部边缘迁移至番禺低隆起。盆地结构及断裂系统的时空差异性受盆地基底先存构造、地壳与岩石圈结构及伸展量等多方面因素的影响,但主要是对软流圈流动及岩石圈热结构变化的响应。用软流圈由北西向南东流动拖曳上覆岩石圈发生伸展变形的动力学模型能合理地解释珠江口盆地中段古近系构造的形成和演化。 相似文献
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The Abitibi belt is one of the largest and most extensively studied Late Archean greenstone belts. The structural geology of the Abitibi belt consists of one generation of upright to slightly overturned, doubly plunging first-order folds with half-wavelengths of 20–60 km, and E–W-striking, steeply dipping fault zones that are parallel to the fold limbs. Two of the main fault zones are continuous for hundreds of kilometers. Previous tectonic models for the Abitibi belt interpret the fault zones to have formed as extensional growth faults bounding a volcanic-sedimentary basin, which were reactivated as thrusts during subsequent crustal shortening. Other models propose that the fault zones represent tectonic sutures, implying that the Abitibi belt is a collage of exotic terranes. However, distinct geological terranes have not been geologically demonstrated. We propose a new detachment fold model for the deformational history of the southern Abitibi belt, in Ontario, that explains the formation of the fault zones during the single, well-documented folding event that deformed the entire region. The internal structure of the fault zones, documented here with emphasis on the Porcupine–Destor fault zone, consists of isoclinally folded, strongly schistose, highly metamorphosed rock, cross-cut by numerous fault segments. We interpret that the upper crust (greenstones) was folded above a proposed detachment in the lower part of the volcanic stratigraphy. The fault zones would be, in essence, highly evolved detachment anticlines. Ultramafic metavolcanic rock that crops out within the fault zones would represent material from the detachment horizon that was emplaced in the cores of the detachment anticlines. The numerous segments that make up the mapped fault zones would be linked faults that formed within the isoclinal detachment anticlines to accommodate folding of the rheologically complex greenstones. The detachment fold model is compared to the results of analogue experiments designed to investigate crustal-scale folding, using viscous and frictional materials. Detachment folds are produced in the brittle upper crustal analogue on the limbs of folds formed in the ductile middle and lower crust analogues. The experimentally produced structures scale to the structures in the study area and indicate the detachment fold model for the southern Abitibi is mechanically viable. 相似文献
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By a detailed investigation of geometry and kinematics of the Shangma (商麻) fault in Dabieshan (大别山),three different crust levels of extension movement have been recognized in sequence from the deep to the shallow:① low-angle ductile detachment shearing with top to the NW; ② low-angle normal fault with top to the NW or NWW in brittle or brittle-ductile transition domain; ③high-angle brittle normal fault with top to the W or NWW. Two samples were chosen for zircon U-Pb age dating to constrain the activity age of the Shangma fault. A bedding intrusive granitoid pegmatite vein that is parallel to the foliation of the low-angle ductile detachment shear zone of the country rock exhibits a lotus-joint type of boudinage deformation,showing syn-tectonic emplacing at the end of the ductile deformation period and deformation in the brittle-ductile transition domain. The zircon U-Pb dating of this granitoid pegmatite vein gives an age of (125.9±4.2) Ma,which expresses the extension in the brittle-ductile transition domain of the Shangma fault. The other sample,which is collected from a granite pluton cutting the foliation of the low-angle ductile detachment shear zone, gives a zircon U-Pb age of (118.8±4.1) Ma,constraining the end of the ductile detachment shearing. Then the transformation age from ductile to brittle deformation can be constrained between 126-119 Ma.Combined with the previous researches,the formation of the Luotian (罗田) dome,which is located to the east of the Shangma fault,can beconstrained during 150-126 Ma. This study gives a new time constraint to the evolution of the Dabie orogenic belt. 相似文献
18.
龙门山中段山前带浅层冲断系统的结构、形成与演化 总被引：4，自引：0，他引：4
本文依据断层相关褶皱几何学原理,对龙门山中段地震剖面进行了精细解释。研究发现,龙门山中段山前带浅层冲断系统存在多套滑脱层,具有上下分层变形特征。浅层滑脱层为上三叠统须家河组三段(T_3~x3)的碳质页岩夹煤层,其上发育双重构造和叠瓦构造;下三叠统嘉陵江组四、五段(T_1j~(4-5))的膏岩层,发育断层传播褶皱、冲起构造和构造楔;深层为下寒武统的泥页岩层,发育断层转折褶皱和滑脱褶皱。该区滑脱断层所控制的地层变形和缩短量各不相同,其中三叠系上统缩短量最大,大于30 km;三叠系下统至古生界地层缩短量约为14.5 km;侏罗系以上的地层缩短量则较小。研究区内的通济场断裂(F_3)为印支末期形成的一套逆冲断层组,其下部交于下寒武统滑脱层,深度约为10 km;关口断层(F_4)和彭县断裂(F_5)为晚侏罗世一早白垩世形成的逆冲断层,下部交与下三叠统嘉陵江组滑脱层,深度大约为8～10 km。这些断层以前展的方式破裂,并且长期活动。龙门山中段自中生代以来存在多期构造事件,主要发生诺利末期、印支晚幕、燕山期和喜马拉雅期。其中,燕山期和喜马拉雅期是龙门山活动最强烈的两个阶段,在龙门山中段山前带表现为大量断裂的长期活动,地壳缩短和龙门山快速隆升,并形成多种构造样式。 相似文献
19.
郯庐断裂带张八岭隆起北段的左旋走滑挤压变形及其~(40)Ar/~(39)Ar定年 总被引：4，自引：0，他引：4
郯庐断裂带张八岭隆起北段,自西向东分别出露北北东向的韧性滑脱变形带、脆-韧性过渡带和脆性的前陆褶断带。韧性滑脱变形带内的张八岭群片岩,广泛发生了低绿片相背景下的糜棱岩化。其中呈现为平缓的糜棱面理和近南北向的矿物拉伸线理。显微构造及石英C轴组构分析显示,该韧性滑脱带一致为上盘向南的运动。该带以东依次变为上盘向南南东→南东的逆冲活动,总体上为左旋走滑挤压变形带。张八岭群所在的韧性变形带为深部陡立走滑构造与浅部脆性构造之间的滑脱变形带,其间的差异走滑变形,造成了该滑脱层在总体向北运动中出现上盘向南的剪切变形。对6处张八岭群片岩中15个不同粒级白云母的40Ar/39Ar定年指示,变形发生在(236.2±0.5)~(238.0±0.4)Ma的中三叠世晚期。这表明郯庐断裂带的左行平移发生在华北与华南板块碰撞的深俯冲阶段,起源于陆内转换断层。 相似文献