Mechanical models of fracture reactivation and slip on bedding surfaces during folding of the asymmetric anticline at Sheep Mountain, Wyoming     

Pablo F. Sanz  David D. Pollard  Patricia F. Allwardt  Ronaldo I. Borja 《Journal of Structural Geology》2008,30(9):1177-1191

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南海的形成演化与新特提斯在南海的重新活化          下载免费PDF全文

蔡周荣  张毅  刘维亮  万志峰  刘平 《沉积与特提斯地质》2008,28(3):21-24

南海位于印度板块、欧亚板块和太平洋板块之间,是世界上最大的边缘海,其构造位置处于太平洋构造域和特提斯构造域,地质构造复杂.关于南海形成演化的动力学机制存在有多种不同观点,其中最重要的一个观点是印度板块与欧亚板块的碰撞致使华南地块和印支地块地幔物质沿东南方向蠕动,从而导致南海的海底扩张.从特提斯的演化规律,以及新特提斯的闭合过程来看,南海并不是特提斯洋的残留海,而是新特提斯在闭合过程中配合印度板块与欧亚板块碰撞导致华南地块和印支地块地幔物质东南方向蠕动的动力学机制下,在南海重新活化的结果.  相似文献   

浑河断裂带（抚顺段）近期活动性与地质灾害的关系   总被引：1，自引：0，他引：1  

王声喜  张庆义  王卓  赵永利  刘宝华 《地质灾害与环境保护》2008,19(4):12-15

通过对浑河断裂带（抚顺段）的地质调查、人工地震勘查、断裂绝对年龄测定、跨断裂形变测量等资料的综合分析与研究,讨论了断裂构造的近期活动特征,并据此认为浑河断裂自晚更新世以来若非人类工程活动扰动是没有活动的,现今的断裂活化效应是由于大量的人类采煤活动造成的。由于断裂的活化效应破坏了抚顺煤田及其周围区域原始构造应力场的平衡状态,为达到新的平衡必然导致应力的重新集中与释放,在此过程中伴随产生了抚顺煤田广泛发育的滑坡、地面沉陷、矿震、地裂缝等地质灾害。  相似文献   

西藏昌都夏通街滑坡成因分析及治理对策     

辜利江  王海兰  赵其华 《中国地质灾害与防治学报》2005,16(2):53-57

西藏昌都地区夏通街滑坡是在古滑坡体上复活的新滑坡。自2001年以来滑坡变形破坏迹象日趋严重，引起了各方的关注。通过对滑坡的现场调查，了解其形成的地质背景。并对变形情况进行长期监测。在分析其变形特征的基础上，对古滑坡体的复活成因机理进行了分析研究。夏通街新滑坡是多种因素综合作用形成的。如河流冲刷、人类工程活动、降雨、地质条件等。其中起控制作用的主要因素是不合理的人类工程活动，特别是修建214国道对坡脚的开挖，使其抗滑段遭到破坏，抗滑力减小。另一控制因素则是连续3a的强降雨，使坡体岩土体力学性质降低，最终导致古滑坡体复活。根据对滑坡变形破坏情况的研究，提出相应的主动防治与被动防治相结合的治理对策。  相似文献   

The Role of Pre-existing Structures in the Origin, Propagation and Architecture of Faults in the Main Ethiopian Rift     

Tesfaye Korme  Valerio Acocella  Bekele Abebe 《Gondwana Research》2004,7(2):467-479

Four major fault systems oriented N–S to NNE–SSW, NE–SW, E–W and NW–SE are identified from Landsat Thematic Mapper (TM) images and a high resolution digital elevation model (DEM) over the Ethiopian Rift Valley and the surrounding plateaus. Most of these faults are the result of Cenozoic - extensional reactivation of pre-existing basement structures. These faults interacted with each other at different geological times under different geodynamic conditions. The Cenozoic interaction under an extensional tectonic regime is the major cause of the actual volcano-tectonic landscape in Ethiopia. The Wonji Fault Belt (WFB), which comprises the N–S to NNE–SSW striking rift floor faults, displays peculiar propagation patterns mainly due to interaction with the other fault systems and the influence of underlying basement structures. The commonly observed patterns are: curvilinear oblique-slip faults forming lip-horsts, sinusoidal faults, intersecting faults and locally splaying faults at their ends. Fault-related open structures such as tail-cracks, releasing bends and extensional relay zones and fault intersections have served as principal eruption sites for monogenetic Plio-Quaternary volcanoes in the Main Ethiopian Rift (MER).  相似文献   

Reaction localization and softening of texturally hardened mylonites in a reactivated fault zone, central Argentina   总被引：6，自引：0，他引：6  

S. J. WHITMEYER  R. P. WINTSCH 《Journal of Metamorphic Geology》2005,23(6):411-424

The Tres Arboles ductile fault zone in the Eastern Sierras Pampeanas, central Argentina, experienced multiple ductile deformation and faulting events that involved a variety of textural and reaction hardening and softening processes. Much of the fault zone is characterized by a (D2) ultramylonite, composed of fine‐grained biotite + plagioclase, that lacks a well‐defined preferred orientation. The D2 fabric consists of a strong network of intergrown and interlocking grains that show little textural evidence for dislocation or dissolution creep. These ultramylonites contain gneissic rock fragments and porphyroclasts of plagioclase, sillimanite and garnet inherited from the gneissic and migmatitic protolith (D1) of the hangingwall. The assemblage of garnet + sillimanite + biotite suggests that D1‐related fabrics developed under upper amphibolite facies conditions, and the persistence of biotite + garnet + sillimanite + plagioclase suggests that the ultramylonite of D2 developed under middle amphibolite facies conditions. Greenschist facies, mylonitic shear bands (D3) locally overprint D2 ultramylonites. Fine‐grained folia of muscovite + chlorite ± biotite truncate earlier biotite + plagioclase textures, and coarser‐grained muscovite partially replaces relic sillimanite grains. Anorthite content of shear band (D3) plagioclase is c. An30, distinct from D1 and D2 plagioclase (c. An35). The anorthite content of D3 plagioclase is consistent with a pervasive grain boundary fluid that facilitated partial replacement of plagioclase by muscovite. Biotite is partially replaced by muscovite and/or chlorite, particularly in areas of inferred high strain. Quartz precipitated in porphyroclast pressure shadows and ribbons that help define the mylonitic fabric. All D3 reactions require the introduction of H⁺ and/or H₂O, indicating an open system, and typically result in a volume decrease. Syntectonic D3 muscovite + quartz + chlorite preferentially grew in an orientation favourable for strain localization, which produced a strong textural softening. Strain localization occurred only where reactions progressed with the infiltration of aqueous fluids, on a scale of hundreds of micrometre. Local fracturing and microseismicity may have induced reactivation of the fault zone and the initial introduction of fluids. However, the predominant greenschist facies deformation (D3) along discrete shear bands was primarily a consequence of the localization of replacement reactions in a partially open system.  相似文献   

Emplacement of sandstone intrusions during contractional tectonics     

《Journal of Structural Geology》2016

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基于SBAS- InSAR技术的西藏雄巴古滑坡变形特征   总被引：2，自引：0，他引：2  

闫怡秋  郭长宝  张永双  张绪教  郑岳泽  李雪  杨志华  吴瑞安 《地质学报》2021,95(11):3556-3570

大型古滑坡及其强变形和复活灾害日益频发,已造成重大灾害事件和严重损失.古滑坡的发育、变形影响因素多、机理复杂和识别难度大,本文采用SBAS-InSAR技术,结合遥感解译,获取了金沙江西岸雄巴村古滑坡2017年10月至2020年6月间的地表变形特征.研究表明,雄巴古滑坡方量巨大,可达2.6×108～6×108 m3,根据InSAR形变监测结果,滑坡前缘发育H1和H2等2个大型强变形区,变形级别分为4级:极强变形区(-132.1 mm/a≤VLOS＜-58.5 mm/a)、强变形区(-58.5 mm/a≤VLOS＜-20.3 mm/a)、中等变形区(-20.3 mm/a≤VLOS＜l.8 mm/a)和弱变形区(1.8 mm/a≤VLOS＜55.4 mm/a);其中H1变形区,最大累计变形量达203.8 mm,H2变形区变形量达302.1 mm.受金沙江河流侵蚀,特别是上游75 km的2018年10月和11月白格2次滑坡-堵江-溃坝-泥石流/洪水灾害链对雄巴古滑坡坡脚的侵蚀,加剧了雄巴古滑坡的变形,其中H1变形区的蠕滑速率是白格滑坡灾害链发生前的14～16倍,灾害链引起H2区发生变形,雄巴古滑坡整体呈现牵引式复活状态.基于SBAS-InSAR的形变监测结果得到了野外的验证,目前H1变形区前缘出现局部垮塌,滑体中横向和竖向裂缝发育,局部呈现拉张状态.雄巴古滑坡目前呈现持续变形中,部分地段为加速变形,雄巴古滑坡发生大规模复活将导致堰塞金沙江-溃坝-泥石流灾害链,应加强雄巴古滑坡的空—天—地一体化监测预警,为该区正在规划建设的重大工程和流域性地质安全风险提供技术支撑和科学依据.  相似文献   

Multistage deformation of linked fault systems in extensional regions: An example from the northern Perth Basin,Western Australia     

T. Song  P. A. Cawood 《Australian Journal of Earth Sciences》2013,60(6):897-903

Linked fault systems identified in the northern portion of the onshore Perth basin comprise north‐striking normal faults, the dominant structures in the basin, and hard linkages—east‐striking transfer faults. The former are either divided into segments of distinctive character by, or terminate at, the transfer faults. The fault systems were initiated by west‐southwest‐east‐northeast extension in the Early Permian but were reactivated by subsequent rifting with approximately east‐west extension in the Jurassic. They were also reactivated by the oblique extension of northwest‐southeast orientation associated with Gondwana continental breakup in the Late Jurassic ‐ earliest Cretaceous. In addition to reactivation, older structures of the linked fault families controlled the development of younger fractures and folds. During the oblique extension, the linked fault systems define releasing bends, characterised by a rollover anticline in the hangingwall of the Mountain Bridge Fault, and restraining bends where contractional folds are sites of major commercial hydrocarbon fields in the basin.  相似文献   

Cenozoic folding in the Cumuruxatiba basin,Brazil: An approach to the deformation trigger by the Abrolhos magmatism     

《Marine and Petroleum Geology》2014

The Cumuruxatiba basin is located in the central portion of the eastern Brazilian margin surrounded by Cenozoic magmatic highs that belong to the Abrolhos Magmatic Complex. This basin was formed by rifting, in the Neocomian followed by thermal subsidence during late Cretaceous like other basins along the Eastern Brazilian margin. In the Cenozoic, the Abrolhos magmatism took place as sills and dykes intruded the sedimentary section, primarily during the Paleogene. In that time, there was a strong NS contractional deformation in the basin represented by folds related to reverse faults coeval with Abrolhos magmatism activity. The structural restorations of regional 2D seismic sections revealed that most of the contractional deformation was concentrated at the beginning of the Cenozoic with maximum peak at the Eocene (up to 33% of total shortening and rate of 6 km/Ma). The Post-Eocene period was marked by a decrease in the strain rate that continues to the present day (around 4 km/Ma to less than 1). 3D structural modelling exhibited a major, well-developed E–W to NE–SW fold belt that accommodated most of the contractional Cenozoic deformation between Royal Charlotte and Sulphur Minerva magmatic highs. Volcanic eruptions and magmatic flows from the Abrolhos complex resulted in differential overburden on edge of the basin, acting as a trigger for halokinesis and the subsequent formation of fault-related folds. In general, such structures were developed close to adjacent magmatic highs, commonly exhibiting vergence towards the centre of the basin. Some magmatic features formed coeval with Cenozoic syn-deformation sediments clearly indicate that Abrolhos magmatism activity and contractional deformation development were associated. The study of the thickness variation of the syn-deformation section in relation to fault-related folds on deformation maps and maximum strain diagrams revealed that most folds were activated and re-activated several times during the Cenozoic without a systematic kinematic pattern. This lack of systematic deformation might be related to the variation of the magmatic pulse activity of adjacent magmatic highs resulting in a complex interference pattern of Cenozoic folds. These structural interpretations of the timing of fault-related folds that are potential Cenozoic traps in the Cumuruxatiba basin play a fundamental role in petroleum systems and exploration of low-risk hydrocarbon prospects.  相似文献