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1.
地壳不同构造层次岩石变形机制及其构造岩类型 总被引：1，自引：0，他引：1
构造岩记录地壳构造变形演化重要信息,其成因、分类与命名一直没有统一认识。本文对构造岩变形机制、控制因素和构造岩分类进行系统总结。认为构造岩形成受物质成分、变形机制、应变速率、流体、温度、压力等因素控制,是物质成分与物理化学条件、变形机制等众多变量的函数。变形机制包括破裂作用、碎裂流动、晶质塑性、物质扩散、重结晶作用和超塑性流动,不同变形机制出现在不同地壳构造层次中,形成不同的显微组构。依据成因机制、物质组成和组构等标志对构造岩分类与命名进行重新修订,将构造岩划分为碎裂岩系列和变质构造岩系列,前者发育在地壳浅构造层次上,以破裂作用和碎裂流动变形机制为主;后者发育在中深部构造层次上,以晶质塑性、重结晶作用、物质扩散作用和超塑性流动作用为主。碎裂岩系列划分碎裂岩、角砾岩、微角砾岩、超碎裂岩、断层泥和假玄武玻璃;变质构造岩系列划分为构造片岩、糜棱岩和构造片麻岩。依据岩石流变性质、变形机制和构造岩分布,地壳构造层次划分为:脆性域,变形机制以碎裂作用和碎裂流动为主,发育碎裂岩系列;脆-韧性转换域,以晶质塑性、物质扩散和重结晶作用为主,并伴随有碎裂作用,形成糜棱岩、千糜岩和构造片岩;低温韧性域,以晶质塑性、物质扩散和重结晶作为主,发育糜棱岩与构造片岩;高温韧性域,以超塑性蠕变和重结晶作用为主,形成构造片麻岩。 相似文献
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依据渤海湾盆地车镇凹陷车西洼陷陡坡带古近系沙河街组沙三下段岩心、测井以及三维地震资料,对研究区的“源-汇”系统进行了研究。结果表明:(1)车西洼陷沙三下段为一个三级层序,并可进一步划分为低位、湖侵与高位3个体系域,其陡坡带沙三下段发育杂基支撑中砾岩、碎屑支撑中砾岩、杂基支撑细砾岩、碎屑支撑细砾岩、砂质砾岩、含砾砂岩、粗砂岩、中砂岩、细砂岩、递变层理砂岩、滑塌岩等11种重力流成因岩石类型及深湖泥岩,表现为典型的近岸水下扇沉积;不同体系域时期扇体规模整体呈“由大变小,再变大”的演化趋势。(2)车西洼陷陡坡带自西向东识别出6套供源体系,可分为有沟道为主供源体系和滑塌为主供源体系,分别形成沟道供源为主近岸水下扇和滑塌供源为主近岸水下扇类型,其中滑塌供源为主近岸水下扇中的滑塌变形构造更发育、更普遍,但其扇体规模较沟道供源为主近岸水下扇小。(3)进一步的“溯源”分析结果表明,沙三下段沉积时期,研究区物源区母岩以碳酸盐岩为主,其在强烈的构造活动、湿热气候作用下,易于发育石漠化古地貌,剥蚀作用较为强烈,由此形成的频发的季节性重力流进入湖盆,形成该地区的近岸水下扇沉积;不同体系域时期扇体规模的差异主要受物源区气候和植被覆盖的控制。 相似文献
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Within fold-thrust belts, the junctions between salients and recesses may hold critical clues to the overall kinematic history of fold-thrust belts. The deformation history within these junctions is best preserved in areas where thrust sheets extend from a salient through an adjacent recess. We examine one such junction within the Sevier fold-thrust belt (western United States) along the Leamington transverse zone, northern Utah. The Canyon Range thrust sheet can be traced continuously from the Leamington transverse zone to its adjacent salient to the south, the Central Utah segment. Deformation within the Canyon Range thrust sheet took place by faulting and cataclastic flow. Analyses of these fault networks preserved throughout the Canyon Range thrust sheet are used to develop a kinematic history of the Leamington transverse zone. Field data is supplemented by analog sandbox experiments. This study suggests that, in detail, deformation within the overlying thrust sheet may not directly reflect the underlying basement structure. Moreover, these junctions may contain several types of accommodating structures that helped to maintain critical-taper and that serve as potential targets for natural resource exploration. 相似文献
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Deformation within the upper crust (elastico-frictional regime) is largely accommodated by fractures and conjugate faults. The Coulomb fracture criterion leads us to expect that the average dihedral angle of conjugate-fault sets is expected to be ∼60°. Experiments, however, reveal a significant amount of scatter from this 60° average. The confining pressure under which these rocks are deformed is a contributing factor to this scatter.The Canyon Range syncline, Sevier fold-thrust belt (USA) and the Jebel Bani, Anti-Atlas fold-belt (Morocco) both folded under different depths, within the elastico-frictional regime, by cataclastic flow. Conjugate-fault sets assisted deformation by cataclastic flow. The Canyon Range syncline and the Jebel Bani are used here as natural examples to test the relationship between the dihedral angle of conjugate-faults and confining pressure. Variations is confining pressure are modeled by the difference in depth of deformation and position within the folds.Results from this study show that the dihedral angle increases with an increase in depth and within the hinge regions of folds, where space problems commonly occur. Moreover, the shortening directions based on the acute bisectors of conjugate-faults may not be accurately determined if the dihedral angles are unusually large or small, leading to incorrect kinematic analyses. 相似文献
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A Quaternary interglacial lake sediment record from the Piànico-Sèllere Basin (northern Italy) consists of biochemical calcite varves with intercalated detrital layers. At the end of the Piànico Interglacial, continuous varve formation was replaced by predominantly detrital sedimentation. However, 427 varve-years before this shift, an abrupt increase in the frequency and thickness of detrital layers occurred. Microfacies analyses reveal a total of 152 detrital layers, ranging from 0·2 to 20·15 mm in thickness, deposited during the last 896 years of the Piànico Interglacial. Three microfacies types are distinguished: (i) graded layers, (ii) non-graded silt layers, and (iii) matrix-supported layers. The position of detrital layers within an individual varve provides additional information on the season in which they have been deposited. Microfacies analyses in combination with varve counting further enabled precise varve-to-varve correlation of the detrital layers for two sediment sections cropping out ca 130 m apart. The detailed intra-basin correlation allows the source regions of detrital layers to be inferred. Moreover, micro-erosion at sub-millimetre scale has been established. Of the described facies types, only the accumulation of summer and spring graded and non-graded silt layers abruptly increased before the end of interglacial varve formation whereas non-graded winter silt and matrix-supported layers are randomly distributed over the entire study period. Heavy rainfalls are assumed to have triggered spring and summer graded layers, so that the occurrence of these layers is thought to be a proxy for extreme precipitation events in the past. 相似文献
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四川省宁南县跑马铅锌矿地质特征及找矿前景分析 总被引：1，自引：0，他引：1
宁南跑马铅锌矿集中产于下寒武统麦地坪段潮坪一泻湖相的粘土一藻白云岩一硅质白云岩组合中，受平行不整合面和褶皱的层间破碎带、裂隙密集带、断裂等控制，为典型的沉积改造型矿床；矿床经历了沉积和改造两个成矿期，即在麦地坪段沉积过程中铅、锌初始富集形成矿源层，经后期热液叠加改造富集成矿，矿区具备大型铅锌矿床的成矿条件，找矿前景良好。 相似文献
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Single-layer and massive boulder beds, which include boulder pavements, are sporadically distributed in the glaciogenic Permo-Carboniferous Dwyka Formation. These matrix-supported beds consist of moderately to poorly sorted, rounded boulders, cobbles and pebbles with a clast composition similar to those in the underlying or overlying diamictite. Alternatively, the clasts are composed of monolithic basement rock-types. The clasts show a long-axis orientation which, in the case of the boulder pavements, is parallel to the striae on the pavements. The various types of boulder beds have a similar mode of deposition and their subglacial origin is evidenced by the clast orientation, clasts with stoss and lee sides, stacking of clasts, and the development of a cleavage in the matrix due to horizontal stresses exerted by the boulders in the subglacial sediment. Subglacial streams, kame mounds, subaqeously winnowed till, or boulder beaches supplied the coarse debris which was entrained in the basal ice by plastic flow and regelation. Selective lodgement of the transported boulders occurred down-glacier when the basal thermal conditions changed from cold-freezing to warm-melting. The formation of the different types of boulder beds is thought to depend primarily on the concentration of coarse debris in the basal ice. 相似文献
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The study of granitic plutons of the Baikal Highland and the Tien Shan has made it possible to establish new features of their posthumous (after incorporation into the consolidated Earth’s crust) structural reworking and to understand the implications of the cataclastic flow for the exhumation of the crystalline basement in the studied regions. It is shown that granitic plutons undergo appreciable structural transformation at the stages of tectonic reactivation that is significantly separated in time from the moment of formation of plutons as geological bodies. The 3D cataclastic deformation is the main mode of structural reworking of granitic plutons, while the cataclastic flow is the main form of their mobility. Newly recognized slice structures characterize the volumetric deformation of granites. 相似文献
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Folding at upper crustal levels occurs by bending of beds and flexural slip between beds. As a fold's interlimb angle decreases, changes in bed thickness and limb rotation are accommodated by various mechanisms, depending on deformation conditions. In the elastico-frictional (EF) regime, cataclastic flow may be the dominant mechanism for fold tightening. The Canyon Range (CR) syncline, located in the Sevier belt of central Utah, shows this type of deformation. The fold involves three thick quartzite units, with slight lithological variations between them. Fold tightening took place in the EF regime (<2 km overburden) by cataclastic flow, involving collective movement on a distributed network of fractures and deformation zones (DZs) from the micro- to the outcrop-scale. In detail, the degree of cataclastic deformation varies significantly across the fold due to minor variations in initial bedding thickness, grain size, matrix composition, etc. A cooperative relationship exists across different scales, and the fracture networks result in a fracture shape fabric that is relatively homogeneous at the outcrop-scale.The initial outcrop scale fracture/DZ network geometry is a product of the growth and linking of micro-scale cataclasite zones, which in turn is controlled by primary lithological variations. Once a fracture network forms, the material behavior of the fractured rock is unlike that of the original rock, with sliding of fracture-bound blocks accomplishing ‘block-controlled’ cataclastic flow. Thus, initial lithological variations at the micro-scale largely control the final deformation behavior at the largest scale. During progressive fold tightening, additional factors regulate cataclastic flow, such as fracture/DZ reactivation or healing, during folding. Although initial lithological variations in different units may produce unique network geometries, each unit's behavior may also depend upon the behavior of adjacent units. In the CR syncline, during the initial stages of cataclastic flow, the inherent nature of each quartzite unit results in unit-specific fracture network geometries. As deformation progresses, unit-specific networks begin to interact with those in surrounding units, resulting in feedback mechanisms regulating the later stages of network development. Thus, the nature of cataclastic flow changes dramatically from the initial to the final stages of folding. 相似文献
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The paper describes the mechanical and microstructural characteristics associated with the brittle to cataclastic flow transition in an orthoquarzite (Oughtibridge Ganister), and compares its microstructural development with features of cataclastic deformation of rocks in nature. The brittle to ductile transition in dry ganister occurs at about 600 MPa at room temperature. At lower pressures shear oriented grain boundary cracks form both pre and post peak strength, loosening the microstructure to the point at which axial transgranular cracks develop. Fault zone localization then occurs. At high pressures fault localization is suppressed by friction, and cataclastic flow occurs by the formation of ultracataclasite shear zones around each grain boundary, Rhomb shaped, relatively intact grain cores survive to high (greater than 20%) strains. Hardening mechanisms responsible for the ductility are discussed. It is shown that natural zones of intense cataclasis (fault zones) often develop microstructures comparable with those seen in these experiments, but the less intense cataclastic flow often associated with folding of rocks at high crustal levels in the external zones of orogenic belts is not comparable inasmuch as grain-scale catalaclasis does not normally occur. It is emphasised that finite strain microstructural similarity does not necessarily point to comparable deformation paths and stress history. 相似文献
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现有公路（铁路）工程中的高陡岩质边坡,特别是风化作用强烈地区的岩质边坡,浅表层岩体多呈碎裂状。采用传统SNS主动防护网加固后,仍经常产生局部失稳、掉块等现象,部分甚至引起整体失稳。因此,针对破碎岩质边坡的加固防护迫切需要进行结构及其设计方法改进。本文提出一种锚墩式主动防护网新型组合结构及其受力计算和设计方法,可有效防止碎裂岩质边坡坡面破坏,同时保证边坡整体稳定。工程应用表明,该组合防护结构具有良好的破碎岩质边坡加固效果,值得在工程建设中推广应用。 相似文献
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在近期的矿山接替资源找矿过程中,对店房金矿以西的角砾岩体西段勘查新圈定5条金矿体。金矿体的形态与产状严格受断裂构造控制,直接产于火山机构的环状、放射状构造和蚀变破碎带之中,矿石分为石英脉型和构造蚀变岩型,围岩蚀变以硅化和黄(褐)铁矿化为主,成矿作用分为2期4个阶段;稳定同位素和流体包裹体研究表明,成矿流体主要为幔源,并具低盐度和多源特点,以岩浆热液为主,成矿温度为中、低温,主成矿期为燕山晚期,店房角砾岩体西段金矿床属与火山构造有关的中、低温热液矿床。 相似文献
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青海双朋西-斜长支沟地区金矿成矿地质条件及成矿规律 总被引：9，自引：0，他引：9
双朋西—斜长支沟地区是青海东部较为重要的贵金属和有色金属成矿区。在已探明的金矿床中,有矽卡岩型、破碎蚀变岩型、石英脉型三类。金的成矿作用受构造-岩浆控制,在不同的岩性组合中分布着不同类型的金矿。矽卡岩型和石英脉型金矿赋存于二叠系中,破碎蚀变岩型金矿赋存于三叠系中。 相似文献
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SIMON P. TODD 《Sedimentology》1989,36(4):513-530
Within high-density flood flows a prominent mechanism of gravel transport and deposition is by stream-driven, high-density traction carpet (with a rheology similar to grain flow). These gravel carpets are envisaged to form the basal portion of a bipartite high-density flood flow, decoupled from an overlying sand- and silt-laden turbulent flow. Several examples already documented in the literature are reviewed and an additional case from the Lower Old Red Sandstone of southwest Ireland is presented. Two mechanisms of traction carpet initiation are discussed: by rapid entrainment of gravel into suspension on rising stage, followed by settling into the gravel traction carpet at peak and falling stage; and by overconcentration of a ‘normal’, low-density bedload. Gravel entrainment, suspension and traction carpet development are significantly easier if the flood water already carries a high concentration of sand and silt in suspension. Theoretical consideration further shows that gravelly traction carpets can be maintained in channels of relatively low gradient by the shear stress exerted by the high-density, sand-bearing turbulent flood flow above. This tangential shear stress is converted to dispersive pressure, which aids buoyancy and quasi-static grain-to-grain contacts in the support of the clasts within the gravel carpet. The carpet is thought to have a quasi-plastic rheology but behave much like a viscous fluid at high shear rates. Stream-driven gravelly traction carpets are expected to produce sheet-like units of clast- to matrix-supported conglomerate, characterized by a parallel or an a(p)a(i) clast fabric. These units may be ungraded, normally or inversely graded, depending on the rate of shear, the viscosity of the flow and the celerity of deposition. 相似文献
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河南南召响水河锑矿床位于秦岭褶皱系北秦岭分区南召―方城小区;中元古界宽坪群四岔口组下段主要岩性为绢云石英片岩,工业锑矿体直接赋存于绢云石英片岩中碎裂石英岩带内,响水河锑矿床成因类型为低温热液充填交代型矿床;工业锑矿体形态为大的不规则陡倾斜脉状体;围岩蚀变主要有硅化、绢云母化和绿泥石化,金属矿化为辉锑矿化、黄铁矿化;矿石自然类型为石英辉锑矿型,按结构构造可分为细脉状矿石、浸染状矿石和块状矿石;矿石矿物成分为辉锑矿,氧化后形成锑华;分析矿床成因机理为花岗斑岩岩浆期后低温含矿热液沿构造裂隙贯入于碎裂石英岩带内,在节理或裂隙发育处富集成矿;且总结了矿床找矿标志。 相似文献
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海域孔隙型天然气水合物储层中,水合物主要以颗粒胶结、包裹胶结、骨架支撑、孔隙悬浮4种赋存模式充填沉积物孔隙,水合物饱和度与赋存模式的不同导致了储层弹性和电性的差异,利用声波和电阻率测井资料联合处理可以进行水合物赋存模式的定量表征。首先利用Simandoux公式计算水合物饱和度,然后通过有效介质模型构建的岩石物理模板识别水合物赋存模式,最后计算储层中不同赋存模式水合物的相对占比。以全球范围内三个典型区域(中国南海神狐海域、北美Blake海台、新西兰Hikurangi边缘)为例,利用水合物储层的实际钻探资料,对水合物赋存模式进行定量分析：(1)中国南海神狐海域SH2站位储层中,水合物主要以骨架支撑模式产出,约占水合物总量的64%;(2)Blake海台994C站位储层中,水合物主要为颗粒胶结和包裹胶结模式,分别占总量的27%和51%;(3)Hikurangi边缘U1518B站位的水合物储层中,水合物主要为包裹胶结和骨架支撑模式,分别占总量的32%和47%。前人针对水合物形成和赋存模式的实验研究显示,水合物更易以颗粒胶结、包裹胶结和骨架支撑模式赋存,从侧面验证了上述分析结果的可靠性。本研究使用... 相似文献
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ABSTRACT Laboratory experiments on rock faulting show that processes of particle comminution in fault rocks are influenced by several parameters, including fault strike and normal stress across faults. In nature, normal stress across faults increases with increasing transpressional strike of faults. Accordingly, different structural fabrics and particle size distributions are expected for cataclastic rocks that have developed along faults with different transpressional orientations and comparable displacements within regional-scale strike-slip fault zones. Adjacent bands of cataclastic gouge and breccia were analysed from four small-scale fault zones. All have comparable displacements and very similar protolith (i.e. shallow-water limestone), structure, kinematics, size, and tectonic environment, but different transpressional strikes within the regional-scale left-lateral Mattinata strike-slip fault, Italy. An inverse linear relationship is found between fault transpressional angles and fractal dimensions of particle size distributions from cataclastic rock samples. 相似文献