万福变质核杂岩韧性剪切拆离带的韧性减薄量

万福变质核杂岩韧性剪切拆离带与辽南变质核杂岩相毗邻,位于辽东半岛北部。韧性剪切拆离带从浅部到深层依次发育糜棱岩、糜棱化岩石及条带状片麻岩。以长石碎斑为标志体的糜棱岩三维有限应变测量显示,X轴一直伸长,Y轴保持不变,Z轴一直缩短。极莫尔圆估算的韧性剪切拆离带内糜棱岩及糜棱岩化岩石的运动学表明,糜棱岩面理和线理形成时的运动学涡度为0.74~0.96,平均为0.86,表明万福韧性剪切拆离带形成以简单剪切为主,结合三维有限应变测量结果,可知万福韧性剪切拆离带为一条加长-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,韧性减薄量从8%增加到29%,且韧性减薄量与运动学涡度负相关。     

北喜马拉雅穹隆带雅拉香波变质核杂岩拆离断层系中糜棱岩带构造特征及变形分析

雅拉香波变质核杂岩位于北喜马拉雅穹隆带东端,其拆离断层系的糜棱岩带构成杂岩核部外壳和周缘,带内主要变形岩石类型为石榴石千糜岩、糜棱状片岩、片麻岩和花岗岩,韧性剪切变形组构特征明显,石英和长石的拉长以及云母的定向排列而形成的透入性面、线理.运动学涡度统计和计算结果表明:雅拉香波变质核杂岩拆离系的剪切作用类型是以简单剪切作用为主的一般剪切;剪切带厚度减薄了77%左右;核杂岩南侧和北侧运动学涡度值对比发现,该杂岩属于自南南东向北北西主动伸展形成的不对称体系.分维数统计分析显示,剪切带糜棱岩动态重结晶石英颗粒边界具有自相似性,分维数值为1.05-1.18,初步估算出古应变速率在10-9.2-10-7.3s-1之间,变形古应力为13.7-25.6 MPa,变形温度不低于500℃,表明该变质核杂岩剪切变形发生于高温环境,一种可能的解释是变质核杂岩核部的浅色花岗岩为同构造侵位.     

北喜马拉雅穹隆带雅拉香波变质核杂岩拆离断层系中糜棱岩带构造特征及变形分析

雅拉香波变质核杂岩位于北喜马拉雅穹隆带东端，其拆离断层系的糜棱岩带构成杂岩核部外壳和周缘，带内主要变形岩石类型为石榴石千糜岩、糜棱状片岩、片麻岩和花岗岩，韧性剪切变形组构特征明显，石英和长石的拉长以及云母的定向排列而形成的透入性面、线理.运动学涡度统计和计算结果表明： 雅拉香波变质核杂岩拆离系的剪切作用类型是以简单剪切作用为主的一般剪切；剪切带厚度减薄了77%左右；核杂岩南侧和北侧运动学涡度值对比发现，该杂岩属于自南南东向北北西主动伸展形成的不对称体系.分维数统计分析显示，剪切带糜棱岩动态重结晶石英颗粒边界具有自相似性，分维数值为1.05—1.18，初步估算出古应变速率在10-9.2—10-7.3s-1之间，变形古应力为13.7—25.6MPa，变形温度不低于500℃，表明该变质核杂岩剪切变形发生于高温环境，一种可能的解释是变质核杂岩核部的浅色花岗岩为同构造侵位.     

肥东低角度韧性剪切带内岩石变形特征

肥东低角度韧性剪切带紧邻郯庐断裂带巨大的近直立的左行平移韧性剪切带发育,其岩石变质变形特征具有韧性剪切带的一般特征,即越靠近剪切带内侧,岩石变质变形程度越强,远离韧性剪切带,岩石变质变形强度越弱。低角度韧性剪切带内超糜棱岩变形强烈,变质相可达到角闪岩相,其变质变形程度与直立的郯庐断裂带内超糜棱变质变形程度类似,两者在形成环境和成因类型上统一,具有大陆岩石圈被高角度韧性剪切带切割并沿低角度韧性剪切带逆冲推覆的形成机制。     

辽南变质核杂岩韧性拆离带的变形特征、应变与运动学涡度分析

辽南变质核杂岩西侧为一NNE 走向、NWW 倾向的低角度拆离断层带, 其中韧性剪切带由位于拆离断层带下部的糜棱岩组成, 糜棱岩中所有运动学指向标志都指示上盘向NWW 方向的伸展拆离。基于长石的R_f /φ 有限应变法, 对该糜棱岩进行测量, 结果显示糜棱岩的应变强度(E_s)介于0.36~1.0 之间, 平均0.75。付林图解与霍塞克图解显示应变类型为压扁型(罗德参数υ=0.11~0.98)。使用极摩尔圆法与有限应变法测量糜棱岩面理与线理形成时的运动学涡度, 其值介于0.74~0.96 之间, 平均0.85。使用C′法获得的伸展褶劈理C′形成时的运动学涡度介于0.10~0.84 之间, 平均0.58。依据运动学涡度、有限应变及拆离带的真实厚度, 计算获得拆离带的韧性减薄量为130~705 m。综合以上结论, 辽南变质核杂岩剪切变形机制是以糜棱岩面理与线理发育为代表的早期单剪为主的一般剪切以及以伸展褶劈理发育为代表的晚期纯剪为主的一般剪切。     

鹰峰岩体两侧韧性剪切带中岩石岩相学特征

鹰峰岩体侵位于达肯大阪群和万洞沟群之间,呈扁豆状产出.岩体两侧分布两条韧性剪切带,带内发育变质变形程度不一的糜棱岩.本文主要从岩石学的角度论述了两条韧性剪切带内的岩石岩相学特征,讨论了韧性剪切带以及剪切带内岩石的特征.     

北京市密云水库西水堡子-梨树沟韧性剪切带显微构造特征

北京密云水库西水堡子-梨树沟韧性剪切带的形成与燕山期岩浆活动有关,研究该韧性剪切带的显微构造特征对确定其性质及成因机制具有重要的理论意义。通过野外剖面实测、岩石定向标本采集及镜下显微构造鉴定,表明断层拆离面以下为变质核杂岩,由长英质糜棱岩、糜棱岩化闪长岩、糜棱岩化黑云母片岩及糜棱岩化片麻岩组成。岩石的韧性组构非常发育,长英质矿物中常见蠕英结构、矩形边结构、机械双晶、核-幔结构等。片状矿物中常见S-C组构、云母鱼结构、显微膝折带等。水堡子-梨树沟韧性剪切带为NWW-SEE向剪切的伸展型韧性剪切带。     

韧性剪切带中金成矿地质构造解析方法及找矿预测——以卡拉麦里大断裂带金矿为例

韧性剪切带是地壳中深层次呈带状展布的高应变的韧性断层.韧性剪切带型金矿是一种非常重要的金矿床类型.以卡拉麦里断裂带附近发现的与韧性剪切带型相关的金矿床(金矿点)为研究对象,解剖了韧性剪切带的成矿特征研究,主要从剪切带的构造成因机制、组构特征、剪切带的变形与成矿的关系、金矿与剪切带的关系、成矿模式与成矿预测做了一个深入的分析.大型深剪切断裂应变特征和构造演化控制着金的成矿作用,成矿流体具有多源性,构造叠加和区域构造转换在剪切带长期演化过程中,使得成矿作用具有多期性和复杂性,多种有利累加效应使得成矿作用规模不断提高,从而形成大型剪切金矿带或金矿集中区.     

论赣南大余-南康地区断层破碎硅化带的韧性剪切作用

在赣南大余-南康一带,以往未发现韧性剪切带.通过野外工作和室内研究,发现了南北、北东、北东东、北西4组韧性剪切带,其中包括前人划的混合岩带、震旦系顶部某些"硅质岩标志层"及一些断裂硅化破碎带和石英脉.这些韧性剪切带的地质特征表明,它们早期发生过多次脆性变形,并伴随多次热液活动,形成规模不一的断层硅化带.断层硅化带在地壳浅部发生韧性剪切作用形成由石英初糜棱岩、糜棱岩和超糜岩构成的韧性剪切带.韧性剪切带的形成取决于应力强度和应变速率,与形成深度无关,这与Sibson的韧性剪切带双层模式是相悖的.     

赣北变质核杂岩剪切带中断层岩的构造地球化学分析

通过对江西北部星子地区穿过变质核杂岩的3种杂岩组合(侵入杂岩、构造杂岩和变质杂岩)系统采样测试和质量平衡分析,发现微量同常量元素一样,离子半径小、比重大和电位高的在断层岩中形成聚集系列,反之则为离散系列.稀土元素中∑REE,HREE相对集中,以及配分曲线上扬和Eu亏损等特点.仅在韧性断裂上盘存在某些与一般规律相悖的现象,其总体均受岩石流变分异、力学化学耦合和构造体制反转作用的制约.     

Deformation characteristics and formation mechanism of the Yunmengshan metamorphic core complex

The Yunmengshan metamorphic core complex in the middle part of the Yanshan Fold and Thrust Belt records crust extension processes of the eastern North China Craton during its peak destruction.Development of the metamorphic core complex was controlled by the generally NNE-striking Dashuiyu Shear Zone.The shear zone dips SE and becomes shallower NE-wards,leading to exposures of a ductile shear zone in the southern and middle parts and brittle faults in the northern part.Exposure structures,microstructures,and quartz C-axis fabrics indicate that the ductile shear zone belongs to an extensional shear zone with a top-to-the-SE shear sense.Deformation temperatures of 300–520°C suggest a midcrustal origin for the ductile shear zone.A ductile deformation belt in the footwall of the shear zone is only as wide as 1–3 km,indicating no widespread mid-crustal ductile flow in the region during the deformation.Zircon U–Pb dating of dykes and plutons as well as hornblende and biotite40Ar/39Ar dating demonstrate that the metamorphic core complex originated at 135 Ma and experienced intense shearing of the Dashuiyu Shear Zone,development of the supradetachment basins,and synkinematic intrusion during 135–125 Ma.The metamorphic core complex was subjected to rapid exhumation during 125–114 Ma when the Dashuiyu Shear Zone suffered continuous activity and passive doming.The shear zone and its hanging wall were cut or replaced by a series of brittle faults when they wereuplifted to a brittle regime,showing that exhumation took place in continuous extensional activities.The metamorphic core complex turned into slow exhumation in an extensional regime in the following latest Early Cretaceous.The evolution history suggests that the Yunmengshan metamorphic core complex was developed by the rolling-hinge model,a common formation mechanism for intraplate metamorphic core complexes in the North China Craton,under the continuous NW–SE extension during the Early Cretaceous(135–100 Ma).     

40Ar-39Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng,Inner Mongolia and their tectonic significance

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield 40Ar-39Ar plateau ages of 133 Ma (Bi) and 126 Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordilleran metamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.     

40Ar-39Ar ages of the Louzidian-Dachengzi ductile shear zone near Chifeng, Inner Mongolia and their tectonic significance

The Louzidian normal fault occurs as the eastern detachment fault of the Kalaqin metamorphic core complex. Field observations and microstructural analyses reveal that the Louzidian-Dachengzi ductile shear zone developed in its lower-plate was genetically related to sinistral strike-slips and extensional faulting. Two samples from this ductile shear zone yield ⁴⁰Ar-³⁹Ar plateau ages of 133 Ma (Bi) and 126 Ma (Kp), which are concordant with their isochron ages. The plateau age of 133 Ma (Bi) records the formation age of the ductile shear zone. The inconsistent relationship between the earlier strike-slip ductile shear zone and the later normal fault makes the Kalaqin Quasi-metamorphic core complex distinctive from Cordilleran metamorphic core complex. These ages provide important geochronological data for putting constraints on the formation age and genesis of such ductile shear zones.     

Evolution of the Xiaotian-Mozitan fault and its implications for exhumation of Dabie HP-UHP rocks

The Xiaotian-Mozitan fault （XMF） located north of the Dabie orogenic belt separates the North Dabie complex to the south from the Beihuaiyang low-grade metamorphic rocks to the north. It comprises several NW-striking ductile shear zones and brittle faults. The brittle faults obviously overprinted on the ductile shear zones and promoted the development of the volcanic basins in early Cretaceous to the north, which suggests that the brittle faults were normal faults formed in early Cretaceous during doming of the Dabie orogenic belt. The ductile shear zone superposed on the north Dabie gray gneiss, and it is an important channel where the Dabie HP-UHP rocks exhumed. For obtaining new structural constraint on exhumation of the HP-UHP rocks, we present here experimental results on the microstructure, quartz C-axis fabrics and the microprobe analyses of phengite. The ductile shear zone was determined to be formed at a temperature of 600-650 ℃ and pressure of 1.1 GPa by the mineral deformation, microprobe analyses and geobarometry of Si-in-phengite of the mylonite, the results suggest that the mylonite now exposed on the surface experienced an upper amphibolite-facies metamorphism in the lower crust. The mineral stretching lineation varies from horizontal in the east segment to sub-dip in the west. Shear sense indicators from outcrop and thin sections of orientated specimen and quartz C-axis fabrics suggest that the XMF is a sinistral normal fault. The kinematics analysis of the ductile shear zone indicates that the exhumation of Dabie HP-UHP rocks is the results of a SE-directed extrusion and an anticlockwise rotation around its eastern pivot simultaneously.     

剪切带中斑晶旋转的粘弹性有限元数值模拟

采用粘弹性力学分析程序对太行山阜平地区剪切带中斑晶旋转问题进行了有限元数值模拟。在计算模型中假定：石榴石斑晶为弹性材料,在应力作用下只产生很小的弹性变形;石英、长石质的基质部分为粘弹性材料,它具有随时间变形不断增大的特性。计算结果显示：沿剪切力方向的最大位移能达到模型宽度的3～4倍,相当于简单剪切的角度达到70°以上,斑晶的最大旋转角度能达到60°左右。这样的变形量级已经十分接近野外实际情况。由于目前地壳物质的粘度值基本上是通过间接推测得到的,其可信度较低,因此文中还讨论了基质的粘度变化对变形和应力的影响,分别取了7个不同量级的粘度值(10¹⁷～10²³ Pa·s)进行计算。     

商南-商城断裂带中段大型韧性走滑剪切带研究

商南－商城断裂带中段的韧性剪切带是由多条糜棱岩带及其所夹的变质岩块体组成的大型韧性剪切带。它是以简单剪切为主要变形机制的、于绿片岩相温压条件下形成的韧性剪切带。剪切带内糜棱岩的塑性变形和恢复重结晶作用强烈。糜棱叶理产状多较陡倾，ａ线理近水平，表明为走滑断裂。大量不对称旋转构造指示该剪切带早期为左行剪切，后期在不同地段又叠加上程度不同的右行剪切     

安徽桐城挂车河镇地区东西向韧性剪切带分形特征及其估算应变速率适用性分析

 安徽桐城挂车河镇(挂镇)地区东西向韧性剪切带包括早期长英质韧性主剪切带、晚期镁铁质韧-脆性剪切带和伴生的长英质同向或牵引变形带.两期长英质构造岩中石英动态重结晶新颗粒发育,边界具有锯齿状或港湾状等不同的微观特征,具有统计意义上的自相似性和明显的分形特征.其分形维数介于1.097~1.144,变形温度介于600~700℃,变形条件相当于麻粒岩相和同构造花岗岩;高温流变学方法估算应变速率低于10^-7.27s^-1,镁铁质韧-脆性剪切带伴生初糜棱岩的应变速率比主韧性剪切带糜棱岩的小0.5数量级左右.分形维数可用作变形温度计和应变速率计,但石英颗粒变形实验推导的Kruhl温度计和Takahashi应变速率计在天然变形岩石中应用很少.与其他方法估算的变形温度和应变速率综合对比结果表明,Kruhl温度计是适用的,而Takahashi应变速率计仅适用于低温(T<400℃)条件.     

Microstructural and deformational studies on mylonite in the detachment faults of Yalashangbo dome, North Himalayan domes zone

The Yalashangbo dome, located at the eastern end of North Himalayan domes zone, has a geometry and structure similar to those of a metamorphic core complex. Ductile shear zones formed the detachment system around the dome and these zones are composed of garnet-bearing phyllonite, mylonitic schist, mylonitic gneiss and mylonitic granite. Ductile shear fabrics developed well in mylonitic rocks, and penetrative lineation and foliation were formed by stretched quartz and feldspar and preferred orientation of mica. Polar Mohr diagram method is used to calculate the kinematic vorticity numbers of the shear zones in the detachment system. Results indicate that the shear zone is a thinned shear zone (thinning of 23%) in an extensional setting which underwent a general shear dominated by simple shear. Comparison of the vorticity numbers between the northern and southern flanks of the Yalashangbo dome shows that the dome is an asymmetric system formed by a north-northwest-directed detaching unanimously. Statistical fractal analysis shows that the shapes of dynamically recrystallized quartz grains in the mylonites have characteristics of self-similarity, with fractal numbers ranging from 1.05 to 1.18. From these fractal numbers, the strain rate of the rock was deduced from 10^-9.2 S^-1 to 10^-7.3 S^-1, the differential paleao-stress was 13.7-25.6 MPa during the deformation happened at a temperature over 500 ℃. The ductile shear zones in the detachment system around Yalashangbo dome were formed under a high green-schist grade condition or happened simultaneously with the intrusion of granite.     

The large-scale ductile shear zone in Kuda, western Kunlun

A set of metamorphic suites, previously known as the Precambrian metamorphic basement in Kuda, western Kunlun has been determined as a large nappe ductile shear zone which develops penetrative foliation, oriented stretching lineation, various but consistent kinematic indicators of thrusting from north to south. The microstructure and the supermicrostructure also display the ductile deformation characteristics, and the paleotectonic differential stress is obtained. The metamorphic age is 426–451 Ma dated by⁴⁰Ar/³⁹Ar method. According to tectonic background, it is a product of early Paleozoic accretionary wedge orogenesis in western Kunlun.     

激光立体成形TC4钛合金动态剪切特性研究

采用微型霍普金森压杆装置和双剪切试样对激光立体成形TC4钛合金的高应变率动态剪切特性进行了研究.通过数值模拟方法从应力、应变均匀性和应力三轴度方面对双剪切试样的缺口形状、剪切区宽度和长度进行优化设计.采用实验方法,分析了不同取向的激光立体成形沉积态TC4钛合金的高应变率（10⁴ s^-1量级）剪切性能.结果表明,动态剪切力学性能并没有明显的各向异性,流动应力随应变率的增大而增加,二者大致呈线性关系.