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1.
班公湖—怒江断裂带东段的构造特征   总被引:2,自引:0,他引:2  
班公湖-怒江断裂带是青藏高原羌塘-唐古拉板块与冈底斯-念青唐古拉板块的缝合带。由韧性推覆剪切带,逆冲断裂带,断陷盆地构造带和推覆构造带,以及蛇绿岩,蛇绿混杂岩,深海复理石,古生代变质岩和燕山期花岗岩侵入体等组合而成,是复杂的断裂系统,主要经历了晚三叠世-中侏罗世洋盆的形成和扩张,晚侏我世洋壳俯冲和岛弧形成,早白垩世-晚白垩世早期弧-陆碰撞汇聚和喜马拉期断陷盆地形成,逆冲推覆构造发育的复杂演化历史过  相似文献   

2.
西天山造山带的构造变形特征研究   总被引:7,自引:1,他引:7  
西天山造山带由伊犁中天山北缘-北天山推覆走滑系统、伊犁中天山南缘-南天山推覆走滑系统和两者之间的伊犁地块组成。伊犁中天山北缘-北天山推覆走滑系统包括北天山推覆构造带、伊犁中天山北缘逆冲带和中天山北缘断裂带。伊犁中天山南缘-南天山推覆系统包括中天山南缘逆冲带、南天山北坡增生楔推覆席、南天山北坡早古生代被动陆缘推覆席、南天山南坡晚古生代洋壳-火山弧-复理石复合推覆席、中天山南缘断裂带和南天山南坡断裂带。区域构造和变形构造的研究表明西天山推覆构造主要奠定于早二叠世早期,走滑运动发生于晚二叠世-早三叠世。中新生代,沿古生代构造有进一步的推覆和走滑运动发生  相似文献   

3.
唐贵智  陶明 《中国岩溶》1990,9(4):330-341
杨家岭第四纪推覆构造的主要标志是寒武系角砾状灰岩及白云岩逆冲于志留系砂页岩和全新世崩坡积层之上。推覆构造由推覆体、基座和滑脱面组成。滑脱面的产状为N80~90°E、10~60°/S,呈波状起伏。推覆体内的派生构造指示推覆构造由南向北逆冲。成生联系上,杨家岭推覆构造属南面天阳坪逆掩大断裂带(推覆构造带)的一部分。杨家岭推覆构造经历了一个从第三纪至今的漫长发展历史,其最近的一次强烈活动,据14C测定数据,距今2400年左右。它的出现和活动对三峡工程稳定性将产生严重的影响。   相似文献   

4.
武当山推覆构造由主滑脱面、前缘叠瓦褶断带、中央推覆体带和后缘挤压-伸展带4种构造成分组成,中央推覆体带划分为7个推覆体,各推覆体在平面上呈鳞片状越覆,在剖面上呈道冲叠覆,构成鳞片叠覆的几何模式。  相似文献   

5.
推覆体前锋带是推覆体的重要组成,其变形特点既反映了推覆体发展过程中的推覆动力的作用和应力消失,又反映了受外缘抗阻的相互作用,这方面的研究受到国内外构造学家的关注。推覆体前锋带的变形构造在组成上既有推覆系的组成,又有逆推覆方向上前锋-外缘带的被动变形构造组成,形成了推覆体受阻状态下的复合变形构造。发育在宁镇山脉的汤—仑推覆体前锋带上的变形构造存在五种型式:岩层的大幅度旋转与密集的叠瓦系;反冲构造;具捩断层性质的横向及斜向断层;平卧褶曲的翘起和具优选剪切方位的膝折构造。  相似文献   

6.
柯坪塔格推覆构造几何学、运动学及其构造演化   总被引:29,自引:1,他引:29  
大量野外构造地质调查和深部构造解释表明柯坪塔格推覆构造由多组倒转复式背斜、复式箱状背斜构成的推覆体及其前缘逆冲断裂组成 ,由寒武系—第四系组成的推覆体由北向南逆—斜冲 ,平面上构成向南凸出的弧形推覆构造 ;普昌断裂由各不相连的逆冲斜冲断裂段组成 ,而不是完整的一条走滑断层 ,各推覆体前缘逆冲断裂与各推覆体的普昌断裂段共同构成统一的前缘逆冲斜冲逆冲断裂和推覆构造系统 ;普昌断裂段以西的推覆体具有向东抬升、向西倾覆的鼻状构造特征 ,普昌断裂段以东的推覆体具有向西抬升、向东倾覆的鼻状构造特征 ,普昌基底隆起带是巴楚隆起隐伏在柯坪塔格推覆构造之下的部分。各推覆体前缘断裂在深部均归并于统一的寒武系底部的滑脱面 ,其南浅北深 ,东浅西深 (普昌隆起带以西 )或西浅东深 (普昌隆起带以东 ) (6 10km ) ,埋深较大区发育多组滑脱面。柯坪塔格推覆构造的形成时期为晚第四纪 ,为现今活动的推覆构造系统。文中认为各推覆体向南西的倾覆端基底滑脱面和中新生界内部的滑脱面没有贯通 ,是未来 6级以上地震的发震构造部位。  相似文献   

7.
秦岭南缘大巴山褶皱-冲断推覆构造的特征   总被引:14,自引:0,他引:14  
董云鹏  查显峰  付明庆  张茜  杨钊  张燕 《地质通报》2008,27(9):1493-1508
秦岭造山带南缘的大巴山巨型逆冲推覆构造主要是在秦岭造山带板块俯冲碰撞造山与中、新生代以来陆内造山过程中长期复合作用形成的。详细的室内外构造研究表明,巴山逆冲推覆构造可以巴山弧形断裂带为界划分为北大巴山逆冲推覆构造和南大巴山逆冲推覆构造。北大巴山自北而南依次由安康-武当推覆体、紫阳-平利推覆体、高桥-镇坪推覆体和高滩推覆体逆冲叠置而成。南大巴山则以镇巴-阳日断裂为界,分为北部的前陆冲断褶皱带和南部的前陆褶皱带。北大巴山主要是印支期碰撞造山作用和燕山期陆内逆冲推覆作用叠加改造的结果,南大巴山则主要是燕山期递进变形过程中的产物。构造变形北强南弱,北以冲断褶皱变形为特征,南以皱褶作用为主;北部褶皱紧闭复杂,向南渐变为宽缓的薄皮构造。逆冲作用在时序上具有由北向南扩展传递的特点。  相似文献   

8.
拉萨地块北部逆冲推覆构造系统   总被引:22,自引:0,他引:22  
拉萨地块北部发育大型逆冲推覆构造系统(NLT),由前锋纳木错构造带,根部安多-伦坡拉构造带和底部滑脱构造带所构成,前锋纳木错构造带总体呈WNW向展布,由20多条向北倾斜的逆掩断层,宽阔的韧性剪切带,4条蛇绿岩片带与大量不同类型的构造岩片所组成,根部安多一伦坡拉构造带位于班公-怒江缝合带中段,由3条WNW向一近EW向逆冲断裂带,宽阔的绿蛇混杂岩岩片中与发生褶皱的古近纪盆地所组成,底部为中上地壳滑脱带,对应于15~30km深处的高导层,主要由蛇绿岩和构造岩组成,NLT推覆距离达120~150km,主要形成时代为古近纪晚期一新近纪早期。  相似文献   

9.
广西十万大山前陆总断推覆构造   总被引:3,自引:0,他引:3  
张岳桥 《现代地质》1999,13(2):150-156
通过十万大山盆地内地地震剖面资料和TM遥感图象和地质构造解译,结合重力资料和野外地质观察及构造分析,阐述了十万大山前陆冲断推覆构造的发育特征和前陆盆地的构造演化。前陆冲断推覆构造由3个不同的构造变形带组成:卷入海西和印支花岗岩体的逆冲断裂带,充填中生代陆相沉积并发生构造滑脱的前陆盆和地对应于华南淮地台的前陆腹地。  相似文献   

10.
云南澜沧地区的逆冲推覆构造很发育.可划分为老厂、孟连一澜沧、孟梭及竹塘一澜沧等四个带。推覆构造由推覆体、飞来峰、构造窗、逆冲断层及原地系统等组成,推覆体变形弱、褶皱不发育,符合冲断式推覆模式,具有双重逆冲构造结构.宏观与微观构造都表明形成于较浅的构造层次。推覆构造的形成演化与澜沧裂谷的发展有关,可划分为三期。逆冲推覆的区域应力来自地体向东的碰撞拼接,是印度板块与扬子板块汇聚的重要构造事件。  相似文献   

11.
安徽省主要构造地质要素的变形   总被引:1,自引:0,他引:1       下载免费PDF全文
安徽省在中国东部的中心部位,跨越不同的构造地质单元。前寒武纪变质岩出露面积约占基岩出露面积的三分之一。变质岩包括太古宙、元古宙及少部分古生代地层;变质相包括麻粒岩相到低级绿片岩相。其中发育有多期褶皱变形和同变质期的断层作用,这些断层在后继变形过程中被改造和复活,形成十分复杂的构造地质图案。  相似文献   

12.
Within the Çokkul synform, Caledonian metamorphic rocks of the Middle Köli Nappe Complex (MKNC) are in low-angle fault contact with the basement mylonites derived from the Precambrian Tysfjord granite-gneiss. In the synform, the MKNC is composed of four fault-bounded nappes each of which has a distinct tectonic stratigraphy composed of amphibolite-facies metamorphosed pelitic and psammitic schists with minor lensoidal bodies of mafic and ultramafic rocks. Pelitic rocks from the three structurally lowest nappes contain the low-variance AFM mineral assemblages gar + bio + staur and staur + ky + bio with mu + qtz + ilm, whereas staur and ky are absent from the highest nappe, the Kallakvare nappe. AFM mineral assemblages in the three lowest nappes indicate peak metamorphic temperatures of 610–660°C and peak pressures in excess of 600 MPa. Mineral assemblages from the Kallakvare nappe are not as diagnostic of metamorphic grade. However, rocks from that nappe contain coexisting plagioclases from both sides of the peristerite gap, suggesting lower-grade peak P–T conditions than those of the structurally lower nappes. In addition, biotite from the lower nappes is more Ti-rich than biotite from the Kallakvare nappe. However, gar–bio–mu–plag and gar–bio–ky–plag–qtz thermobarometry suggests that all four nappes equilibrated at approximately 525 ± 25°C and 700 ± 100 MPa. Gibbs method thermodynamic modelling of garnet zoning profiles suggests that the lower three nappes followed clockwise P–T paths that involved heating and compression to a metamorphic peak of approximately 575–625°C, 800 MPa followed by cooling and decompression to 525°C, 700 MPa. P–T paths calculated for the Kallakvare nappe show decompression and minor heating to a peak T of 500–525°C. In the lower nappes, staur and ky grew during the heating phase not seen by the highest nappe. The outer parts of the paths from all four nappes are approximately parallel, possibly recording the emplacement of the Kallakvare nappe onto the already stacked lower three nappes at some time following the metamorphic peak. These P–T paths suggest that the sole fault of the Kallakvare nappe is a normal fault. Garnet zonation thus appears to record a previously unrecognized phase of uplift and tectonic thinning of the MKNC. This event appears to be restricted to the MKNC and to have occurred prior to the emplacement of the MKNC onto the Tysfjord granite-gneiss basement of Baltoscandia under greenschist-facies conditions. It may have been responsible for the uplift and cooling of the MKNC from 25–30 km amphibolite-facies conditions prior to its emplacement onto Baltoscandia under 15–20 km greenschist-facies conditions. The deformation zone associated with this normal fault is relatively narrow, generally less than 1 m thick. If this is typical of other detachment faults in the metamorphic infrastructure of the Scandinavian Caledonides, they may be relatively common, but not often recognized due to the detailed study needed to document them.  相似文献   

13.
TECTONIC EVOLUTION OF THE GARZE—LITANG PLATE JUNCTION, WITH PARTICULAR REFERENCE TO THE GOLD DEPOSITS  相似文献   

14.
江汉平原古生界构造结构特征及油气勘探方向   总被引:6,自引:1,他引:6  
江汉平原古生界具有北西—南东向分为三块、北东—南西向分为三带及纵向上多层楼的构造结构特征。三个区块为当阳—京山构造区、荆州—仙桃构造区及鄂城—大冶构造区,每个区块均可划分出三个次级构造带,并在全区形成三个构造变形分带。这三个分带在变形强度、构造样式等方面具有特征性差异:北东侧的构造分带受东秦岭—大别山造山运动产生的挤压应力的直接作用,显示以逆冲推覆结构为主要特征;南西侧的构造分带在三个构造区有差别,在当阳—京山构造区形成斜坡稳定带,在另两个构造区则以推覆叠瓦构造为特征;中部构造分带一般显示前缘断褶或复合叠加构造。当阳—京山构造区东部和鄂城—大冶构造区应以逆冲推覆体为勘探对象;荆州—仙桃构造区的仙桃地区应以上古生界油气藏为勘探目标;当阳—京山构造区西部宜昌稳定带和荆州—仙桃构造区的珂理—簰洲地区则应以下古生界油气藏为勘探目标。  相似文献   

15.
黑龙江省漠河推覆构造特征及其与金成矿的关系   总被引:3,自引:0,他引:3  
漠河推覆构造发育于上黑龙江盆地的北西部,是漠河地区的主要构造样式,形成于晚侏罗世-早白垩世之间。推覆方向总体由NW向SE,具有前展式的扩展方式。推覆构造在空间上由一系列近平行排列的逆冲断层组成,剖面上表现为犁式逆冲断裂所构成的单冲式叠瓦状构造,按其变形变质特征可划分为6条构造分带。漠河推覆构造对上黑龙江盆地金矿床的时、空分布具有明显的控制作用,其中砂宝斯金矿床受控于推覆构造脆性断裂破碎带,矿体产于构造界面之上的层间破碎带和SN向陡倾断裂破碎带中;老沟、砂宝斯林场金矿床受控于推覆构造韧性剪切带,矿体产于NE向脆性构造破碎带中。金矿床(点)主成矿期为早白垩世。综合研究漠河推覆构造的控矿特点,对该区实现新的找矿突破具有重要意义。  相似文献   

16.
The boundary zone between two Penninic nappes, the eclogite-facies to ultrahigh-pressure Zermatt-Saas zone in the footwall and the blueschist-facies Combin zone in the hanging wall, has been interpreted previously as a major normal fault reflecting synorogenic crustal extension. Quartz textures of mylonites from this fault were measured using neutron diffraction. Together with structural field observations, the data allow a refined reconstruction of the kinematic evolution of the Pennine nappes. The main results are: (1) the contact is not a normal fault but a major thrust towards northwest which was only later overprinted by southeast-directed normal faulting; (2) exhumation of the footwall rocks did not occur during crustal extension but during crustal shortening; (3) the Sesia-Dent Blanche nappe system originated from a continental fragment (Cervinia) in the Alpine Tethys ocean, and the Combin zone ophiolites from the ocean basin southeast of Cervinia; (4) out-of-sequence thrusting played a major role in the tectonic evolution of the Penninic nappes. An erratum to this article can be found at  相似文献   

17.
通过龙永聚煤盆地构造演化及富煤带赋存层段机理分析,发现聚煤盆地构造演化与富煤带展布有一定的相关性,主要表现在一定时期、一定空间、一定样式的构造与一定层段的富煤带在走向、倾向上,具有一定的相关性,即一定的富煤带产生在一定的滑覆、推覆构造及其组合中。龙永煤田西部主要产生印支期的滑覆断层,应寻找走向上的富煤带;龙永煤田东部主要产生燕山期的推覆断层,应寻找倾向上的富煤带;龙永煤田中部主要产生印支期及燕山期的组合滑脱断层,应寻找上推下留型、上滑下留型、滑褶集中型的走向、倾向的富煤带。此项研究为龙永煤田进一步寻找富煤带指明了方向,同类型的勘探区可以参考。  相似文献   

18.
The Austroalpine nappe systems in SE-Switzerland and N-Italy preserve remnants of the Adriatic rifted margin. Based on new maps and cross-sections, we suggest that the complex structure of the Campo, Grosina/Languard, and Bernina nappes is inherited largely from Jurassic rifting. We propose a classification of the Austroalpine domain into Upper, Middle and Lower Austroalpine nappes that is new because it is based primarily on the rift-related Jurassic structure and paleogeography of these nappes. Based on the Alpine structures and pre-Alpine, rift-related geometry of the Lower (Bernina) and Middle (Campo, Grosina/Languard) Austroalpine nappes, we restore these nappes to their original positions along the former margin, as a means of understanding the formation and emplacement of the nappes during initial reactivation of the Alpine Tethyan margin. The Campo and Grosina/Languard nappes can be interpreted as remnants of a former necking zone that comprised pre-rift upper and middle crust. These nappes were juxtaposed with the Mesozoic cover of the Bernina nappe during Jurassic rifting. We find evidence for low-angle detachment faults and extensional allochthons in the Bernina nappe similar to those previously described in the Err nappe and explain their role during subsequent reactivation. Our observations reveal a strong control of rift-related structures during the subsequent Alpine reactivation on all scales of the former distal margin. Two zones of intense deformation, referred to as the Albula-Zebru and Lunghin-Mortirolo movement zones, have been reactivated during Alpine deformation and cannot be described as simple monophase faults or shear zones. We propose a tectonic model for the Austroalpine nappe systems that link inherited, rift-related structures with present-day Alpine structures. In conclusion, we believe that apart from the direct regional implications, the results of this paper are of general interest in understanding the control of rift structures during reactivation of distal-rifted margins.  相似文献   

19.
Abstract P–T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid‐crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Çine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Çine nappe underneath the Selimiye shear zone record maximum P–T conditions of about 7 kbar and >550 °C. Metasedimentary rocks from the overlying Selimiye nappe have maximum P–T conditions of 4 kbar and c. 525 °C near the base of the nappe. Kinematic indicators in both nappes are related to movement on the Selimiye shear zone and consistently show a top‐S shear sense. Metamorphic grade in the Selimiye nappe decreases structurally upwards as indicated by mineral isograds defining the garnet‐chlorite zone at the base, the chloritoid‐biotite zone and the biotite‐chlorite zone at the top of the nappe. The mineral isograds in the Selimiye nappe run parallel to the regional SR foliation, parallel the Selimiye shear zone and indicate that the Selimiye shear zone formed during this prograde greenschist to lower amphibolite facies metamorphic event but remained active after the peak of metamorphism. 40Ar/39Ar mica ages and the tectonometamorphic relationship with the Eocene Cyclades–Menderes thrust, which occurs above the Selimiye nappe in the study area, suggests an Eocene age of metamorphism in the Selimiye nappe. Metasedimentary rocks of the Çine nappe 20–30 km north of the Selimiye shear zone record maximum P–T conditions of 8–11 kbar and 600–650 °C. An age of about 550 Ma is indicated for amphibolite facies metamorphism and associated top‐N shear in the orthogneiss of the Çine nappe. Our study shows that simple monophase tectonometamorphic fabrics do not always indicate a simple orogenic development of a nappe stack. Preservation in some areas and complete overprinting of those fabrics in other areas apparently occur very heterogeneously.  相似文献   

20.
The nappe pile presently cropping out in the central sector of the Ligurian Alps, is represented by some principal groups of tectonic units. Starting from the foreland, the outer and lower, weakly metamorphic (up to 0.3 GPa) Briançonnais units support the high-pressure (up to 1.3 GPa) ensemble of inner Briançonnais nappes, in turn overridden by the Prepiedmont units, sourced from the European continental margin. Prepiedmont units form two superposed groups. The lower is composed only of a pre-Namurian basement (Alpine metamorphism up to 0.6 GPa); and the upper is mainly composed of a slightly metamorphic (greenschist facies) post-Namurian cover. At the top lie the high-pressure metamorphosed (up to 0.8 GPa in the sector here considered) ophiolitic units. The group of the non-metamorphic Helminthoid Flysch nappes (original stratigraphic cover of the ophiolitic units) has travelled the greatest distance and is presently mainly set onto the outer part of the chain. Only events up to the stacking of the nappe pile are discussed, disregarding late-stage deformation. As the examined sector is located at a considerable distance from the collisional zone, late processes did not change the overall order of superposition formerly acquired. The model proposes the development of two major, subhorizontal detachment surfaces. The first, shallower one confines at the base a very thin-skinned set of nappes, nearly totally made up of Prepiedmont sedimentary covers that are bounded at their top by the Helminthoid Flysch units. Both these groups underwent a mainly horizontal outwards transport. In contrast, the underlying Prepiedmont crust and the adjoining Briançonnais inner sector (separated by the second, deeper major detachment surface) were progressively dragged into the subduction zone under the ophiolitic units and duplexes were generated. Exhumation of the metamorphic units occurred along the subduction channel, as did stacking of the nappe pile.  相似文献   

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