云南丽江-剑川断裂带活动性研究   总被引：1，自引：0，他引：1  

许晶莉  刘顺  张燕 《云南地质》2012,(1):113-116,92

断裂带左旋运动起始于新构造运动。早更新世丽江盆地形成之后,斜向穿过丽江盆地的丽江-剑川断裂带对丽江盆地形成现今形态有很强的改造作用。丽江-剑川断裂带最新的一次活动应在早更新世后,以脆性变形为主,韧性变形为辅的断裂带,近期活动深度不很大。  相似文献   

东天山-北山造山带中大型韧性剪切带属性及形成演化时限与过程   总被引：10，自引：5，他引：5  

蔡志慧  许志琴  何碧竹  王瑞瑞 《岩石学报》2012,28(6):1875-1895

塔里木盆地北缘的东天山-北山造山带中发育多条近E-W走向的大型韧性剪切带,它们构成了造山带中不同地体单元的主要边界,是碰撞造山及造山后的产物。本文在野外调查基础上,通过微观/宏观构造、几何学/运动学/动力学/年代学相结合的研究、厘定了东天山北山造山带中的7条大型韧性剪切带,阐述了剪切带的延伸、规模、剪切变形特征、变形条件以及形成与演化时限。并讨论了这7条不同类型韧性剪切带的形成过程以及东天山和北山古生代造山过程中所起的重要作用。  相似文献   

Orogen-transverse tectonic window in the Eastern Himalayan fold belt: A superposed buckling model     

《Journal of Structural Geology》2014

The Eastern Lesser Himalayan fold-thrust belt is punctuated by a row of orogen-transverse domal tectonic windows. To evaluate their origin, a variety of thrust-stack models have been proposed, assuming that the crustal shortening occurred dominantly by brittle deformations. However, the Rangit Window (RW) in the Darjeeling-Sikkim Himalaya (DSH) shows unequivocal structural imprints of ductile deformations of multiple episodes. Based on new structural maps, coupled with outcrop-scale field observations, we recognize at least four major episodes of folding in the litho-tectonic units of DSH. The last episode has produced regionally orogen-transverse upright folds (F₄), the interference of which with the third-generation (F₃) orogen-parallel folds has shaped the large-scale structural patterns in DSH. We propose a new genetic model for the RW, invoking the mechanics of superposed buckling in the mechanically stratified litho-tectonic systems. We substantiate this superposed buckling model with results obtained from analogue experiments. The model explains contrasting F₃–F₄ interferences in the Lesser Himalayan Sequence (LHS). The lower-order (terrain-scale) folds have undergone superposed buckling in Mode 1, producing large-scale domes and basins, whereas the RW occurs as a relatively higher-order dome nested in the first-order Tista Dome. The Gondwana and the Proterozoic rocks within the RW underwent superposed buckling in Modes 3 and 4, leading to Type 2 fold interferences, as evident from their structural patterns.  相似文献   

大别造山带东缘韧性剪切带中构造岩的构造地球化学分析          下载免费PDF全文

李振生  牛浩  田晓莉  张文俊 《地质科学》2014,(2):472-493

安徽省桐城市挂镇（挂车河镇）地区出露郯庐断裂系（北北东-北东向）和大别构造系（近东西向）的韧性剪切带,变质温度分别为400 ℃～450 ℃和600 ℃～700 ℃,均发育镁铁质和长英质构造岩,是研究不同变形条件下岩石中元素活化迁移规律的理想对象。质量平衡计算表明长英质剪切带在韧性变形过程中,大别构造系体积基本不变,郯庐断裂系体积亏损且随变形程度的增强而增加,镁铁质性剪切带在脆-韧变形过程中体积增加。长英质构造岩的稀土和微量元素变异远弱于镁铁质构造岩,长英质构造岩基本继承了原岩的特征而镁铁质构造岩与原岩的差异显著,长英质和镁铁质混合的构造岩主要显示镁铁质组分的迁移规律。长英质构造岩的元素迁移种类和迁移率与变形程度和变质温度正相关,其中体积亏损变形的郯庐断裂系表现为重稀土中等迁出、中稀土几乎未迁移和轻稀土微弱迁入,等体积变形的大别构造系为稀土元素迁入,轻稀土、中稀土和重稀土的迁移率依次增加。镁铁质构造岩的稀土元素迁移表现为轻稀土强烈迁入和重稀土中等迁出。体积变化不是元素变异的主因,在原岩和矿物蚀变制约的基础上,元素迁移受到岩石流变分异作用和热液渗流作用的双重作用,低温时以渗透流体作用为主,而高温时岩石流变分异作用增强。  相似文献   

北大城地区韧性剪切带特征及金矿化     

邓岩波 《国土资源》1992,(4)

北大城金矿是受韧性剪切带控制的小型金矿。韧性剪切带分布在北大城—马鹿沟一带,总体呈北东东—近东西向展布,发育于太古宙建平群小塔子沟组的区域变质岩中。韧性剪切带早期以韧性剪切为主,晚期以脆性变形为主。韧性剪切带内由初糜棱岩、糜棱岩,超糜棱岩组成。宏观微观构造明显。金矿化带分布在韧性剪切带内的晚期断裂构造中,为石英脉型和蚀变岩型。  相似文献   

商南地区秦岭群中的韧性伸展构造     

裴先治  胡能高  高进龙 《地球科学与环境学报》1993,(Z1)

在秦岭造山带核部秦岭群变质岩系中,发育有自NWW向SEE方向拉伸的深层次韧性伸展构造。表现为具有定的代表伸展运动方向的塑性拉伸线理、不对称顺层韧性剪切褶皱及横向置换面理等。态因后期挤压收缩作用已发生改变。伸展作用发生于加里东期挤压收缩、构造叠置、陆壳增厚之后,与晚加里东—早海西期大量花岗质深成岩体的上隆侵位密切相关,伸展作用方向近平行造山带走向,时代可能为早海西期。  相似文献   

Block-supported cataclastic flow within the upper crust     

《Journal of Structural Geology》2013

Recent work from portions of the Sevier fold-thrust belt that have deformed primarily within the elastico-frictional regime, demonstrates that cataclastic flow can be subdivided into two types: matrix- and block supported. The two types may operate simultaneously within the same deforming material. However, their activity can vary spatially, temporally and across scales. Although block-supported cataclastic flow is a critical process in upper crustal deformation, it continues to be largely ignored and/or misunderstood, primarily because established concepts and definitions for cataclastic flow are chiefly based on matrix-supported cataclastic flow. Here, block-supported cataclastic flow is examined to better understand cataclastic flow in general and to explore its relationship with matrix-supported cataclastic flow.  相似文献   

Tectonic evolution of the deep crust: Variscan reactivation by extension and thrusting of Precambrian basement in the Bragança and Morais massifs (Tras-os-Montes,NE Portugal)     

F.G. Marques  A. Ribeiro  E. Pereira 《Geodinamica Acta》2013,26(1-2):135-151

Abstract

The Braganca amd Morais Massifs (NE Portugal) comprise a pile of four nappes on lop of the Autochthon of the Central-Iberian Zone : a Parautochthon (PTC), a Lower Allochthon (LATC), an Ophiolitic Complex (OTC) and an Upper Allochton (UATC). This article focuses on the tectonic evolution of the prc-Variscan basement preserved in the Upper Allochthonous Thrust Complex. (1) In the Morais Massif, the UATC is mainly composed of orthogneisscs, micaschists and high-grade melamorphic rocks restricted to a small duplex between the orthogneisses and the ophiolitic complex. The orthogneisses are pervasively deformed by D6 (Variscan D1). characterized by NNW-SSE stretching lineation, C-S structures, and sense of shear to the SSE. The high-grade melamorphic rocks show at least three ductile deformation phases older than the gneisses deformation. The micaschists and the orthogneisses are cut by mafic sills and dykes transformed into amphibolites by the Variscan tec-tonometamorphic evolution. In a restricted domain where dykes arc less deformed, two deformation events can be recognized and arc considered to be pre-Variscan. The walls of the dykes show a N-S stretching and mineral lineation interpreted as resulting from D6 (Variscan D1). (2) In the Braganca Massif, the UATC comprises mafic to ultrainafic igneous and high-grade melamorphic rocks, and paragncisses with ky-eclogite lenses. Six ductile deformation phases are recognized. The D1 to D4 events may correspond to a complete pre-Variscan orogenic cycle, from subduction (D1) to collision (D2-DS) and thrusting of the high-grade metamorphic rocks to upper levels in the crust (D3-D4); D5 may result from the Lower Palaeozoic extensional event that marks the begining of the Variscan Wilson cycle; D6 is interpreted as the first Variscan orogenic event with southward movement. The UATC of the Cabo Ortegal anil Braganca Massifs comprise mainly upper mantle/lower erustal rocks. By contrast, the UATC of the Ordenes and Morais Massifs is mainly composed of middle to upper erustal rocks. Vic propose that this is the result of a regional ductile normal fault (extensional event) that was active prior to the Variscan orogeny, in Lower Palaeozoic times, and affected a Precambrian basement.  相似文献   

碧口地块北缘大型韧性剪切带的构造、成矿意义   总被引：1，自引：0，他引：1       下载免费PDF全文

李新生  牛卯胜  张崇 《甘肃地质》2004,13(1):54-60

碧口韧性剪切带沿康县—碾坝—麻子坝一带呈连续带状展布,发育于泥盆系及震旦系关家沟组上岩段内部。该韧性剪切带对碧口群区域构造解析、构造运动学、动力学研究及成矿研究具有重大意义。  相似文献   

养马甸子韧性剪切带岩石矿物特征     

刘义德 《国土资源》1990,(2)

养马甸子韧性剪切带发育在花岗岩房胜沟超单元,麻计沟似斑状二长花岗岩单元内,为一韧性平移剪切带,呈右行。据韧性剪切带中岩石矿物的应变特征,计算出该韧性剪切带剪应变值为1.24—2.32,形成深度为13—20km,温度为450—650℃,围压为325—550MPa,最大剪应力为σ=113—141MPa,差异应力为31—35MPa。■棱岩富SiO_,贫Al_2O_3、Na_2O和K_2O,各种矿物显微旋转应力结构发育,具铜矿化。  相似文献