北京北石城断层带与河防口断层带断层岩石显微构造研究

本文论述了糜棱岩类与碎裂岩类的变形特征,它们各自代表了不同的成因机制,反映了断层带经历过早期韧性剪切和后期脆性破裂的发育历史。根据断层岩石的显微构造特征,估算了断层带发育过程中两个阶段的温度、压力、应变速率、差异应力大小和方位,并讨论了韧性剪切带、地壳中弹塑性过渡带与大陆地震多发层之间的关系     

沂沭断裂带中段基底韧性剪切带

在沂沭断裂带中段的泰山群结晶基底中,存在着一系列北东、北北东走向的左行韧性剪切带。对其中发育糜棱岩的韧性剪切带的结构构造、应变测量、变形岩石的显微构造、显微组构以及长石粒度和含量的变化规律进行了观测分析。讨论了韧性剪切带的变形条件和机制。及其递进发展的趋势。指出基底韧性剪切带是沂沭断裂带元古宙时期断裂活动时在地壳较深层次上形成的构造表象。在此基础上,讨论了地壳不同层次上的断裂变形及断裂岩石的综合分类问题     

Multiple generations of pseudotachylyte in the brittle to ductile regimes, Qinling–Dabie Shan ultrahigh-pressure metamorphic complex, central China

Abstract Pseudotachylytes are present along the Dahezhen shear zone in the Qinling–Dabie Shan collisional orogenic belt, central China. Two types of pseudotachylyte vein are documented in the shear zone: cataclasite‐related pseudotachylyte (C‐Pt) and mylonite‐related pseudotachylyte (M‐Pt). M‐Pt is associated with mylonite‐development and is overprinted by C‐Pt. All of the quartz and most of the feldspar porphyroclasts within the M‐Pt are plastically deformed, but not in the C‐Pt. Dynamically recrystallized fine‐grained quartz and feldspar bands are oriented subparallel to the mylonite and M‐Pt foliation, and partially surround the porphyroclasts. Our results suggest that the M‐Pt formed cyclically in the ductile region at estimated conditions of 400–650°C and 400–800 MPa due to propagation of seismic fracturing associated with the thrusting‐related rapid exhumation of the ultrahigh‐pressure metamorphic complex in the brittle regime down to a greater depth than the base of the seismogenic zone. The M‐Pt and mylonite formed in the Dahezhen shear zone at estimated conditions of 400–650°C and 400–800 MPa. The coexistence of C‐Pt and M‐Pt in the same shear zone suggests that repeated seismic slips occurred in both the brittle and ductile portions of the crust during the thrusting‐related rapid exhumation of the ultrahigh‐pressure metamorphic complex.     

郯庐断裂带白山-卅铺段第四纪以来的活动习性

根据构造地貌遥感解析,发现郯庐断裂带沿庐江白山到桐城卅铺一线显示1组平行断层,现场地震地质调查验证其为1组活动断层。通过断层剖面观测、样品采集及样品测试分析和宏微观构造分析,结果表明,郯庐断裂带在白山—卅铺一带第四纪以来仍具有黏滑、蠕滑交替的变形活动。其中,在柯坦—卅铺一带,最年轻的水系被NE向断层组右旋扭折,其断层物质的微观观测和测龄结果表明该断裂段第四纪时的活动具有脆、塑性过渡变形特征,强烈活动时间处于早、中更新世;而白山剖面断层泥年龄测试结果则反映相应断层段在中、晚更新世曾有过较强烈的活动。断层泥超微(SEM)和显微观测结果亦表明该断裂段曾发生黏滑、蠕滑交替的构造变形事件,且表现为先黏滑后蠕滑;结合水系呈现缓慢扭折表征,近年来沿断裂有不少微震发生,表明郯庐断裂带在白山—卅铺段的最新滑移方式主要表现为蠕滑,也就是说,该段积累的应力以蠕滑或微震等方式缓慢释放,据此推测未来一定时期内不易孕育强烈地震     

ESTIMATE OF DIFFERENTIAL FLOW STRESS AND STRAIN RATE FOR HONGHE FAULT ZONE

Microstructures of quartz in Honghe mylonite zone are studied and recent result of microstructural paleopiezometry is used in this paper to estimate the differential flow stress and strain rate for the southern Honghe fault zone. The calculations show that the differential flow stress during the development of mylonites of the southern Honghe fault zone varied gradually from 45MPa in the south to 120MPa in the north. Because the formation depth of mylonite zone became shallow from south to north, this variation indicates the decrease of flow stress with depth. The strain rate was roughly of the order of 10-12/se     

Characteristics of fault rocks and paleo-earthquake source along the Koktokay-Ertai fault zone,Xinjiang,China

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高潭—深圳断裂活动性研究

高潭—深圳断裂是广东境内规模巨大的莲花山断裂带的主要组成部分,穿过深圳水库和白盆珠水库,控制并断陷了第三纪红色盆地,多处有热泉出露。据此,不少研究者认为,它有一定程度的新活动。笔者在两个水库区考察了6条剖面并系统采集了断层岩(包括断层泥)样品,应用显微构造分析、石英颗粒表面形貌分析、TL和ESR法进行了变形特征和年龄的分析测定。结果表明,该断裂是在早期形成的规模较大的韧性剪切带(糜棱岩带)的基础上发展起来的,后来有多期脆性断裂活动,最后一次较强烈活动的时间为距今20多万年(中更新世晚期),以后活动强度逐渐减弱。     

Strain and shear types of the Louzidian ductile shear zone in southern Chifeng, Inner Mongolia, China

The Louzidian ductile shear zone at the south of Chifeng strikes NE-SW and dips SE at low-medium- angles. This ductile shear zone is mainly composed of granitic mylonite, which grades structurally upward into a chloritized zone, a microbreccia zone, a brittle fault and a gouge zone. All these zones share similar planar attitudes, but contain different linear attitudes and kinematic indicators. Finite strain measurements were performed on feldspar porphyroclasts using the Fry method. These meas- urements yield Fulin indexes of 1.25―3.30, Lode's parameters of -0.535―-0.112 and strain parameters of 0.41―0.75 for the protomylonite, respectively. These data are plotted within the apparent constric- tional field in Fulin and Hossack diagrams. In contrast, for the mylonite, corresponding parameters are 0.99―1.43, -0.176―-0.004 and 0.63―0.82, respectively, and located in the apparent constrictional field close to the plane strain. The mean kinematic vorticity numbers of the protomylonite and mylonite by using three methods of polar Mohr circle, porphyroclast hyperbolic and oblique foliation, are in the range of 0.67―0.95, suggesting that the ductile shearing is accommodated by general shearing that is dominated by simple shear. Combination of the finite strain and kinematic vorticity indicates that shear type was lengthening shear and resulted in L-tectonite at the initial stage of deformation and the shear type gradually changed into lengthening-thinning shear and produced L-S-tectonite with the uplifting of the shear zone and accumulating of strain. These kinds of shear types only produce a/ab strain facies, so the lineation in the ductile shear zone could not deflect 90° in the progressively deformation.     

断裂带中的二相变形与地震成因讨论

本文主要以郯庐断裂带现代侵蚀面上五种不同类型的断裂构造和断层岩石为例,论述大断层带中岩石变形的二相性特征,包括机械意义的“韧性相”和“脆性相”应变组分在变形过程中的作用和意义。在此基础上探讨一种可能的地震成因方式     

磨子潭-晓天断裂(晓天至佛子岭间)的构造分析

根据断裂带切割变质围岩中各期变形旋回形成的褶皱,断裂带中的断层岩为形成于地表条件下的角砾岩和碎裂岩并切割围岩中各种糜棱岩带,构成上侏罗统火山岩盆地的边界断层等特征,磨子潭-晓天断裂应是晚侏罗世形成于地表条件下的断层;根据断层附近上侏罗统砂岩夹层中的裂隙焊接,磨子潭-晓天断裂在晚侏罗世形成后,还有两次较强烈的活动。据地表、钻探和地震资料,断层面向北倾,倾角向深部变缓     

滇西怒江断裂带新构造特征

怒江断裂带从走向上可以分为南北走向段和北东走向段,其喜马拉雅期的构造变形以右行剪切为主导。右行剪切的变形历史可以分为早期压剪变形和晚期张剪变形两个大的阶段。这两期变形各自在南北走向段和北东走向段表现出不同的特点。总之,怒江断裂带喜马拉雅期构造变形具有时空不均一性的特点     

郯庐断裂带晚第三纪以来的浅部挤压活动与深部过程

郯庐断裂带晚第三纪以来持续遭受着挤压 ,使前期大规模的断陷盆地抬升、消亡 ,近代还是中国东部最大的地震活动带。断裂带所遭受的近WE向的挤压 ,是西太平洋弧后扩张和印度板块向北碰撞中的构造挤出作用产生的区域动力。断裂带在新生代挤压活动中切入上地幔 ,出现了地幔剪切、地幔交代、部分熔融等深部过程 ,最终形成了挤压背景下的陆内断裂带大规模的玄武岩喷发     

水热条件下富层状硅酸盐矿物糜棱岩的摩擦特性实验研究

为探索断层岩石摩擦特性对于断层力学性质的影响,我们采集了龙门山汶茂断裂韧性剪切带中的富含层状硅酸盐矿物的糜棱岩样品进行了水热条件下摩擦滑动实验研究.实验在三轴压机之上完成,实验温度为100~600℃,有效正压力100MPa,孔隙水压分别为30MPa和130MPa.为获得摩擦滑动的稳定性参数(a-b),剪切滑移速率在1.22μm·s-1,0.244μm·s-1和0.0488μm·s-1之间切换.实验发现在200~500℃的温度范围内,摩擦系数随着温度的增加而显著增大(约0.56~0.72).在200~300℃范围内,随温度的升高糜棱岩的摩擦滑动表现出由稳定的速度强化向不稳定速度弱化转变的趋势.在有效正压力不变的情况下,孔隙水压的增大会促进糜棱岩的摩擦滑动在500~600℃温度范围内由不稳定的速度弱化向稳定的速度强化的转变.实验给出的断层在原地深度处的脆性和塑性变形机制的转变,有助于理解断层深部的地震成核机制以及成核的温压条件.     

滇西北发震构造条件及其与鲜水河断裂带的对比

文章在分析滇西北发震构造条件的基础上,把它与鲜水河断裂带进行了对比。滇西北是一个伸展构造区,鲜水河断裂带为一平移剪切带。后者较前者断层面上正应力大、变形强烈、应变速率高。前者断层几何复杂,D?=1.56,后者断层几何简单,D?=1.08-1.2。震源深处变形环境前者者为低压中温,后为高压中温。由此造成地震活动性上的差异     

红河断裂带中南段糜棱岩分形特征及主要流变参数的估算

红河断裂带是一条经历了长期构造演化的块间构造变形带,该断裂的西南侧出露一套经韧性剪切形成的糜棱岩。研究区糜棱岩宏观上发育多种变形组构,如构造面理、线理、S-C组构等。微观变形特征有云母鱼、长石碎斑、长石和角闪石压扁拉长、碎斑旋转形成的压力影等;尤其是石英普遍变形,其特征有波状消光、核幔构造、动态重结晶、单颗粒压扁拉长及石英条带等;石英动态重结晶新颗粒尤其发育,重结晶的新颗粒边界具有锯齿状或港湾状等不同的微观特征,这些不同的特征记录了变形时的温压环境和流变速率。石英新颗粒分维几何统计分析表明:研究区石英动态重结晶颗粒边界形态具有自相似性,表现出分形特征。分维数值为1.150～1.180,变形温度大约500℃,同构造变质环境属高绿片岩相-低角闪岩相;初步估算应变速率可能低于10-8.4s-1,根据石英重结晶的粒径估算变形古应力为42.0～58.0MPa     

Microcosmic analysis of ductile shearing zones of coal seams of brittle deformation domain in superficial lithosphere

For many years, the study on ductile shearing zones mainly focuses on the strain analysis and the characteristics of microcosmic structure of felsic duc-tile shearing zones in deep layers (8—10 km). Discus-sions on the process of the development of small-type and mini-size ductile shearing zones have been re-ported in recent years[1,2]. 揇uctile deformations in brittle deformation擺3] and 揵rittle deformations in ductile deformation擺4] are rather a familiar phenome-non in nature. Researchin…     

Transpressional tectonics of the Mineoka Ophiolite Belt in a trench–trench–trench-type triple junction, Boso Peninsula, Japan

Abstract   Structures developed in metamorphic and plutonic blocks that occur as knockers in the Mineoka Ophiolite Belt in the Boso Peninsula, central Japan, were analyzed. The aim was to understand the incorporation processes of blocks of metamorphic and plutonic rocks with an arc signature into the serpentinite mélange of the Mineoka Ophiolite Belt in relation to changes in metamorphic conditions during emplacement. Several stages of deformation during retrogressive metamorphism were identified: the first faulting stage had two substage shearing events (mylonitization) under ductile conditions inside the crystalline blocks in relatively deeper levels; and the second stage had brittle faulting and brecciation along the boundaries between the host serpentinite bodies in relatively shallower levels (zeolite facies). The first deformation occurred during uplift before emplacement. The blocks were intensively sheared by the first deformation event, and developed numerous shear planes with spacing of a few centimeters. The displacement and width of each shear plane were a few centimeters and a few millimeters, respectively, at most. In contrast, the fault zone of the second shearing stage reached a few meters in width and developed during emplacement of the Mineoka Ophiolite. Both stages occurred under a right-lateral transpressional regime, in which thrust-faulting was associated with strike-slip faulting. Such displacement on an outcrop scale is consistent with the present tectonics of the Mineoka Belt. This implies that the same tectonic stress has been operating in the Boso trench–trench–trench-type triple junction area in the northwest corner of the Pacific since the emplacement of the Mineoka Ophiolite. The Mineoka Ophiolite Belt must have worked as a forearc sliver fault during the formation of a Neogene accretionary prism further south.     

第四纪水泉尖山-崛峿山南麓断裂带活动的迁移及其机制

位于甘肃靖远地区的水泉尖山-崛峿山南麓断裂带早第四纪前为走向逆断 层,第四纪中期出现左旋走滑迹象。研究结果表明,水泉尖山-崛峿山南麓断裂带断裂 活动的横向迁移与海原活动断裂带的形成和强烈活动有着密切的关系。     

第四纪水泉尖山-崛峿山南麓断裂带活动的迁移及其机制

位于甘肃靖远地区的水泉尖山－崛Ｗｕ山南麓断裂带早第四纪前为走向逆断层,第四纪中期出现左旋走滑迹象。研究结果表明,水泉尖山－崛Ｗｕ山南麓断裂带断裂活动的横向迁移与海原活动断裂带的形成和强烈活动有着密切的关系。     

北京密云北石城断裂带的断层岩特征及其地震事件的可能证据

通过对北京密云北石城断裂带的野外和室内工作,该断裂带的断层岩可分为四种类型:碎裂岩类、糜棱岩类、假熔岩和断层泥。它们具有不同的矿物学、形变和组构特征,分别代表不同的成因机制。假熔岩和碎裂岩类断层岩的存在,可作为古地震事件的可能证据。前者是地震断层运动在断层面上摩擦增温,引起围岩中矿物的选择性熔化形成的。在该断裂带中可能发生不止一次的古地震事件。断层岩特征和产状表明,该断裂带经历了两种不同力学性质的运动,早期为韧性剪切;晚期为脆性破裂,并伴有地震发生