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1.
马来西亚沙捞越Punda走滑构造及其动力学成因   总被引:1,自引:2,他引:1  
沙捞越Punda走滑构造为一典型的右旋走滑构造形式,是沿近东西向F断裂(PDZ)发育特征的负花状构造或郁金香构造,并构成走滑伸展双重构造。Luconia陆块与巽他克拉通的碰撞及卢帕断裂的走滑是Punda走滑构造形成的动力学成因。同时,利用Riedel单剪模式和走滑次级构造逐级配套模式可以合理地解释Punda走滑断裂的构造形式。  相似文献   

2.
云南澜沧地区的逆冲推覆构造很发育.可划分为老厂、孟连一澜沧、孟梭及竹塘一澜沧等四个带。推覆构造由推覆体、飞来峰、构造窗、逆冲断层及原地系统等组成,推覆体变形弱、褶皱不发育,符合冲断式推覆模式,具有双重逆冲构造结构.宏观与微观构造都表明形成于较浅的构造层次。推覆构造的形成演化与澜沧裂谷的发展有关,可划分为三期。逆冲推覆的区域应力来自地体向东的碰撞拼接,是印度板块与扬子板块汇聚的重要构造事件。  相似文献   

3.
九龙山构造是川西北地区的重点勘探构造。据地震剖面分析,解析了九龙山的构造几何学特征。研究表明,九龙山背斜受到米仓山构造和龙门山构造的双重影响,主要经历了三期次构造叠加,其叠加组合形成了现今九龙山的复杂构造。通过合理的构造建模,对九龙山构造运动过程、多期构造叠加及油气运移与分布规律等有了新的认识。  相似文献   

4.
滇中砂岩铜矿是中生代陆相碎屑岩铜矿床.滇中含铜砂岩即矿源层形成后,构造对矿床的形成起着双重的控制作用,一是构造控制了成矿物质的活化、迁移、富集,二是构造控制了矿床的位置.文中初步提出了滇中构造控制矿床的规律.  相似文献   

5.
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川东地区属高陡构造发育区,伴随四川盆地经历了华南纪—早古生代、晚古生代—三叠纪、侏罗纪—第四纪3大伸展聚敛构造旋回;具有明显的顺层挤压滑脱与垂向分层特点。围绕下寒武统、下志留统、下三叠统膏泥岩滑脱层可划分为上、中、下3套构造层;在各滑脱层之下,围绕各自所发育的有效烃源岩层,形成各自独立的含油气系统。川东高陡构造主要为印支期形成,燕山期发展,喜马拉雅期改造定型,其构造变形机制总体表现为“断层转折、楔入反冲与双重构造”模式特征。下构造层沿下寒武统滑脱层,形成叠瓦构造、双重构造和楔入反冲构造;中构造层沿下志留统滑脱层,形成断层转折褶皱、对冲构造和反冲构造;上构造层沿下三叠统滑脱层,形成断层传播褶皱、对冲构造和反冲构造。区内天然气资源丰富,主要集中于中构造层,具有下构造层继承性低隆起构造高部位的寒武系—震旦系白云岩与礁滩发育区聚集,中部构造层沿不整合面的潜伏构造围斜部石炭系白云岩与志留系砂体发育区聚集,中部构造层的潜伏构造背斜与向斜区二叠系与下三叠统礁滩与白云岩发育区聚集成藏特点,对应其有利勘探方向。  相似文献   

6.
川东台附状逆断层与韧—脆性变形的显微构造特征   总被引:1,自引:0,他引:1  
川东盆地发育的台附状逆断层,其伴生构造有断层转折褶皱,拖曳褶被、背形堆垛的双重逆冲构造和后陆倾向中的双重逆冲构造,断层岩中方解石的变形,在光学显微镜下表现有波状消光、机械双晶、显微破裂和碎裂等特征,反映了岩石的变形以脆性变形为主,韧性变形为韧-脆性过渡型变形,在变形过程中,断层活动的差异应力值,根据方解石双晶发育程度推导,得出在500巴以上。台阶状逆断层的形成与低角度 断层之间有着密切的关系,其形成机制主要有:(1)形成断坡的滑动和破裂过程,其应变速率大于10^-10/s;(2)位错活动过程,产生阶状断层以及相伴生的褶皱构造,其应变速率在10^-10/s-10^-12/s范围之内。  相似文献   

7.
从松辽盆地的构造反转看中国东部盆地构造圈闭的形成   总被引:6,自引:0,他引:6  
王燮培  宋廷光 《地球科学》1996,21(4):373-382
通过对松辽盆地构造反转的分析,把该盆地构造反划分为3种类型:平面上分为4个反转向构造带,结合中国东部含油气盆地构造样式和演化机制,认为松辽盆地的构造反转不同局部现象,它代表了中国东部裂谷盆地演化的普遍模式,并与构造圈闭,油气藏的形成密切相关,中国东部盆地重要的构造反转4期;盆地内众多构造圈闭类型是多种地质应力联合作用和多期构造作用叠加的结果,而后期的挤压反转到了加剧和定型作用,中国东部燕山-喜山期  相似文献   

8.
立足于中非剪切带的构造演化,文章分析了中非剪切带对多赛奥盆地形成与演化的控制作用,明确了多赛奥盆地的 构造演化阶段,并从盆地结构和构造样式分析入手,探讨了多赛奥盆地的成因机制。研究表明,受中非剪切带“强—弱” 两期走滑作用控制,多赛奥盆地经历了扭张期、压扭期、拗陷期三期的构造演化阶段,扭张期为盆地的主要形成期,压扭 期为盆地构造定型期。在晚白垩世压扭期,盆地东、西部遭受不同程度的压扭作用,形成东部主坳区和西部压扭区,东部 主坳区遭受后期压扭作用较弱,表现为不对称的双断结构特征,而西部压扭区遭受强烈的后期压扭作用,地层发生弯曲变 形,Borogop II断裂发生正反转作用,形成大型正花状构造区。受早期扭张作用和后期压扭作用双重控制,多赛奥盆地发育 两类五种构造样式。右阶右旋作用机制形成的扭张作用控制了多赛奥和塞拉迈特走滑—拉分盆地的形成。  相似文献   

9.
新疆塔里木盆地构造样式研究   总被引:2,自引:0,他引:2  
塔里木盆地是一个复合叠加的大型含油气盆地,经历了多期构造活动的影响,形成了丰富多彩的构造样式,笔者从形成盆地的地球动力学背景出发,将塔里木盆地的构造样式划分为压缩构造样式,伸展构造样式和走滑构造样式三种基本类型,再根据构造的卷入程度,进一步划分为基底卷往型和盖层滑脱型两种类型,同时讨论了由于构造背景转化而形成的反转构造。  相似文献   

10.
米仓山、南大巴山前缘构造特征及其形成机制   总被引:6,自引:0,他引:6  
在对四川盆地东北部盆山结合部地表地质和石油地球物理资料综合分析的基础上,阐述了米仓山前缘构造、南大巴山前缘构造的几何学、运动学特征;发现了二者的共性和不同,二者均以双重构造为主,通过古生代构造层的叠置,而迅速抬升出露地表,米仓山前缘以被动顶板双重构造为主,即典型的"三角带"构造,南大巴山前缘以主动顶板双重构造为其显著特征;初步分析了原因,区域滑脱层,特别是嘉陵江组-雷口坡组膏盐岩滑脱层及古生界泥页岩滑脱层,构成了顶板和底板逆冲断层,其间的台地相碳酸盐岩构成了断夹块,受米仓山早期基底隆升和侧向挤压,形成了被动顶板双重构造,南大巴山递进挤压变形,形成了主动顶板双重构造。  相似文献   

11.
Two Hercynian duplexes are developed in Viséan limestones in the Basse Normandie quarry. The lower duplex is completely exposed in a subvertical quarry wall; the partially exposed upper duplex lies immediately above the lower duplex. The duplexes are both located in the footwall of the Hydrequent thrust which emplaced Devonian clastic sediments above the Viséan limestones. The lower duplex exposes all the internal thrusts, a reference bed of chalky limestone, the roof and floor thrusts, and the duplex tip. The duplex has been graphically restored to its pre-deformation geometry by line-length and area balancing and its resultant geometry is close to the model of Boyer & Elliott. The lower duplex shortened by two different mechanisms, an initial phase of layer-parallel shortening which produced no cleavage, followed by thrust imbrication. The average contraction of the front portion of the duplex was ?49% (natural strain) of which ?27% is layer-parallel shortening and ?22% is thrust imbrication. However, locally the bulk shortening increases from zero at the duplex tip to over ?120% in a down-dip direction. The area balancing provides the most accurate estimates of bulk shortening; line-length balance calculations give minimum estimates only. An area balance on the whole of the lower duplex gives a bulk shortening of ?84%. An area balance of the upper duplex yields an average contraction of ?75% and the total contraction produced by both duplexes is ?92%.  相似文献   

12.
Detailed (1:60 scale) mapping of the Fort Foster Brittle Zone in the mylonitic Rye Formation of southernmost Maine has revealed the intricate internal duplex structure of a system of probable Paleozoic-age dextral strike-slip faults that have produced abundant pseudotachylyte and minor breccia. The internal configuration of this brittle zone consists of a mosaic of individual pseudotachylyte generation zones as slab-duplex structures. Individual duplex zones are up to 100 m in length and 1 m or less in width and are defined by pairs of layer-parallel slip surfaces along which frictional melts were produced. These slab-duplex structures are interpreted as zones of displacement transfer between long, overlapping, layer-parallel en échelon strike-slip fault surfaces. Contractional duplexes develop layer-parallel compressional structures that tend to shorten and thicken the fault-bounded slabs by the formation of lateral ramps and conjugate faults, kinks and asymmetric folds. Extensional duplexes develop layer-parallel stretching and thinning by the formation of oblique dextral shears, high-angle conjugate pairs and localized fault breccias. The production of pseudotachylyte by friction melting along layer-parallel fault surfaces in these exposures is attributed to rapid slip during paleoseismic events. The rupture structures developed during these events may be characteristic of fault structure and mechanics at near-focal depths in a strike-slip seismogenic zone.  相似文献   

13.
This study made it possible to reconstruct three stages of the structure formation at the large Malomyr gold deposit in the Amur Region: (1) premineral folding and left-lateral strike-slip faulting; (2) synmineral thrust faulting, and (3) postmineral dike and neotectonic stage. The study has shown that the formation of the Malomyr deposit was related to the system of duplexes as the structural traps that are the most favorable for ore deposition. The left-lateral duplex hosts the major orebodies composed of refractory ore at the Central site of the deposit, whereas the highest-grade and readily processable ore from the Quartzitic site is localized in the right-lateral duplex. The development of both duplexes during the same stage of thrust faulting indicates that readily processable and refractory ores were formed almost simultaneously. The type of mineralization depends on structural conditions of ore deposition. Refractory ore with invisible gold was formed under compression, whereas the readily processable ore with free gold was deposited in the extension setting.  相似文献   

14.
The Lewis thrust sheet of the southern Canadian Rocky Mountains contains many spectacular examples of small-scale duplex structures. This paper presents the results of a detailed analysis of such structures found in the Mississippian carbonates of the Banff Formation at Crowsnest Pass, southwestern Alberta.Foreland dipping, hinterland dipping and antiformal stacked duplexes are found in the hangingwall of the Lewis thrust. Out-of-sequence thrusts, back thrusts and folds that push out of the plane of the cross-section, termed lateral lobes, give rise to complex internal geometries. Dominant slip vectors are towards 080–090° but the complex fault geometries have generated significant variations in slip away from this direction. The duplex structures occur as discrete thrust fault-bounded packages with each package having different slip vectors. The panels above and below the duplex structures show consistent slip vectors towards 080–090° whereas the duplexes exhibit a wide scatter of slip vectors from 350–160°. The stacking of duplexes with many horses can be likened to the stacking of many inverted soup bowls, herein termed turtle back structures, and will involve a wide scatter of slip directions, particularly if the horses are of limited lateral extent. Such a stacking mechanism involving out-of-section movement invalidates the assumption of two-dimensional plane strain in the plane of the cross-section that contains the regional tectonic transport direction. Correctly balanced cross-sections cannot be constructed through such stacked duplex structures as described in this paper.  相似文献   

15.
在过去的25年里,由于许多原因,作为最常见、分布也最广泛的地质构造形迹之一,逆冲断层成为倍受关注的科学研究主题。文中指出,关于逆冲断层及其几何学特征的许多普遍认识(或观念),并不像以往文献中所阐述的那样简单。其中之一的"薄皮"冲断构造是受地层控制的,极少有或者没有结晶基底物的卷入。文中主张,"薄皮"一词只有逆冲板片的几何学形态含义,而不应包含地层意义,并列举了一些完全由结晶岩石所构成的薄皮逆冲构造的例子来说明这一主张。近来,逆冲双重构造成为构造文献中的热点。关于逆冲双重构造的成因,引用得最多的是1982年Boyer和Elliot在其重要论文"逆冲断层系统"中所作的解释。他们认为,双重道冲构造是通过在冲断坡底部发生下盘破裂。新生断裂不断向前扩展并进入先存断层下盘的一系列变形过程中逐渐形成的。根据Boyer和Elliot提出的这种变形过程,将形成一个具有平面状顶板断层的边冲双重构造,这个顶板断层只在活动断坡的顶部是主动向前扩展的。依笔者之见,在实际的构造变形当中,是不可能具备形成平顶过冲双重构造的地质条件的。而能对平顶过冲双重构造形成作出最好解释的是反序(out-of-sequence,OOS)边冲断层的发育,即断层向着主冲断层的后方发展,在先存道冲构造的上部?  相似文献   

16.
This paper focuses on the behavior of a roof sequence in the Appalachian Plateau of West Virginia, U.S.A., and emplacement of the Wills Mountain duplex with 17.5 km of displacement. Unlike the Plateau along strike in Pennsylvania and New York where forethrusting was previously documented, this roof sequence lacks an underlying salt-dominated roof décollement. Kinematic analyses reveal that the roof sequence in the West Virginian Plateau accommodated about two-thirds of the 17.5 km of shortening by the adjacent Wills Mountain duplex, as a forethrusting kinematic response. The remaining shortening imbalance of about 5 km between the duplexes and younger roof sequence rocks is accommodated by additional forethrusting further into the foreland and local compensation. This kinematic response matches that along strike in the central Appalachians despite the loss of the salt décollement. We interpret that an Ordovician shale-dominated formation was sufficiently weak to substitute for the salt horizon. Thus, a weak mechanical unit rather than specifically a salt décollement is a necessary prerequisite for forethrusting. A contributing factor to forethrusting may be the subvertical front of the Wills Mountain duplex, which inhibited other responses by the roof sequence. Mesoscale and smaller processes, including grain-to-grain pressure solution, twinning and cleavage formation account for over 75% of the shortening in the roof sequence, and, if ignored, would result in an erroneous interpretation of backthrusting or local compensation. This result suggests that failure to consider all deformation scales could lead to incorrect kinematic conclusions in other tectonic systems.  相似文献   

17.
In a cross-section through the southern arm of the Cantabrian Zone, several duplexes have been identified below the Esla Nappe, which is the uppermost and main thrust sheet of the area. The folds deforming the Esla Nappe are culmination walls linked to frontal and lateral ramps belonging to the lower thrust sheets. The thrust sequence can be established on the basis of quantitative analysis of displacement transfer and out of sequence thrusting. The primitive footwall ramps of the Esla Nappe Region were often subsequently broken by décollements developed in successively lower stratigraphic levels of these footwalls. The kinematics of the lowest duplex are more complicated than those of typical duplexes described elsewhere: some thrusts transfer only part of their displacement to the roof thrust, while the remaining part is accommodated along the higher thrusts of previously emplaced duplexes, cutting out of sequence one or more floor or roof thrusts. Cumulative displacement of the thrusts in this region is about 90 km, giving a present thickness 3 times that of the original pre-orogenic sequence, together with a translation of at least 60 km, for the synorogenic basin.  相似文献   

18.
Kinematic models developed here suggest a bewildering array of structural styles can be generated during out-of-sequence thrusting. Many of these structures would be difficult to distinguish from a normally stacked thrust sequence and the process can produce younger-on-older faults that could easily be misinterpreted as normal faults. This paper considers a small subset of this problem within a large model space by considering structures that develop along a pair of ramp-flat faults that are moving simultaneously, or sequentially. Motion on the lower ramp warps the structurally higher fault due to fault-bend folding and when the fault ruptures through the warp it transfers a horse to the upper hanging wall. Continuity of the process generates what is referred to here as an “upper plate duplex” to distinguish the structure from a conventional duplex. Kinematic parameters are developed for two models within this general problem: 1) a system with a fixed ramp in the lower thrust, overridden by an upper thrust; and 2) a double-duplex system where a conventional duplex develops along the lower fault at the same time as an upper plate duplex is formed along the upper fault. The theory is tested with forward models using 2D Move software and these tests indicate different families of structural styles form in association with relative scaling of ramp systems, slip-ratio between faults, and aspect ratios of horse blocks formed in the upper-plate duplex. A first-order result of the analysis is that an upper plate duplex can be virtually indistinguishable from a conventional duplex unless the trailing branch lines of the horses are exposed or imaged; a condition seldom met in natural exposures. Restoration of an upper-plate duplex produces counterintuitive fault geometry in the restored state, and thus, restorations of upper plate duplexes that erroneously assume a conventional duplex model would produce restored states that are seriously in error. In addition, in most of the models some fault segments place younger rocks on older rocks which could be easily misinterpreted as normal fault systems. In some models younger-on-older juxtapositions are significant and if scaled to crustal scale would produce core-complex style structures that would be difficult to recognize as contractional features. Collectively, these observations imply that many areas where simultaneous contraction and extension are inferred may be entirely contractional with younger-on-older relationships generated by out-of-sequence thrust systems. Examples where this process may have occurred are in southwestern North America and the Moine thrust system and future studies should evaluate these systems in light of these models. Distinguishing upper plate duplex from conventional duplex is potentially important in economic evaluations of thrust systems because fluid migration paths would be very different in the two alternatives. The process may also be important in seismogenic mechanisms, particularly in subduction megathrusts, because faults warping faults could produce fault irregularities that would form transient asperities along the fault.  相似文献   

19.
Upper crustal strike-slip duplexes provide an excellent opportunity to address the fundamental question of fault zone development and strain partitioning in an evolving system. Detailed field mapping of the Mesozoic Atacama fault system in the Coastal Cordillera of Northern Chile documents the progressive development of second- and third-order faults forming a duplex at a dilational jog between two overstepping master faults: the sinistral strike-slip, NNW-striking, Jorgillo and Bolfin faults. These are constituted by a meter-wide core of foliated S-C ultracataclasite and cataclasite, flanked by a damage zone of protocataclasite, splay faults and veins. Lateral separation of markers along master faults is on the order of a few kilometers. Second-order, NW-striking, oblique-slip subsidiary fault zones do not show foliated ultracataclasite; lateral sinistral separations are in the range of  10 to 200 m with a relatively minor normal dip-slip component. In turn, third-order, east–west striking normal faults exhibit centimetric displacement. Oblique-slip (sinistral–normal) fault zones located at the southern termination of the Bolfin fault form a well-developed imbricate fan structure. They exhibit a relatively simple architecture of extensional and extensional-shear fractures bound by low displacement shear fractures. Kinematic analysis of fault slip data from mesoscopic faults within the duplex area, document that the NW-striking and the EW-striking faults accommodate transtension and extension, respectively. Examination of master and subsidiary faults of the duplex indicates a strong correlation between total displacement and internal fault structure. Faults started from arrays of en echelon extensional/extensional-shear fractures that then coalesced into throughgoing strike-slip faults. Further displacement leads to the formation of discrete bands of cataclasite and ultracataclasite that take up a significant part of the total displacement. We interpret that the duplex formed by progressive linkage of horsetail-like structures at the southern tip of the Bolfin fault that joined splay faults coming from the Jorgillo and Coloso faults. The geometry and kinematics of faults is compared with that observed in analog models to gain an insight into the kinematic processes leading to complex strike-slip fault zones in the upper crust.  相似文献   

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