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1.
砂岩侵入体是由处于浅埋藏阶段、尚未固结的砂质沉积物发生液化并侵入到上覆盖层所形成的一类软沉积物变形,在北海盆地维京地堑渐新统地层中非常发育。为探讨砂岩侵入体的形态特征及诱发机制,通过高分辨率三维地震及测井资料,利用地震反射结构分析、地震相干切片等手段对砂岩侵入现象进行了识别;并结合多边形断层系统、流体充注与砂岩侵入之间的关联性,对砂岩侵入体的成因机制进行了分析。结果表明:在地震剖面上可识别的砂岩侵入体多呈V型或W型强振幅反射特征,其横向展布规模约1~2 km,垂向侵入高度约100~200 m;流体的大规模充注及多边形断层诱发盖层破裂是形成砂体内部超压并诱发其发生液化的关键因素。砂岩侵入体在形成之后可以作为流体运移通道,对强化流体的垂向运移具有重要意义;并且砂岩侵入体本身即可作为油气的有利储集体。因此识别并分析砂岩侵入体的成因机理,对盖层封闭性评价及油气勘探具有重要指导意义。 相似文献
2.
Granite magma migration and emplacement along thrusts 总被引：1，自引：0，他引：1
Eric C. Ferré Olivier Galland Domenico Montanari Thomas J. Kalakay 《International Journal of Earth Sciences》2012,101(7):1673-1688
This paper investigates the influence exerted by brittle tectonic structures in the emplacement of granite plutons in contractional settings. We address both cases where contractional tectonics and magma intrusion are (1) coeval, to study how active contractional tectonics controls the transport of magma, and (2) diachronous, to study the role of pre-existing structures on the transport of magma. In light of new experimental models, we show that magma can rise along thrusts ramps and flats. This phenomenon occurs for both low-viscosity magma (basalts to andesite) and high-viscosity magma (dry granite). The experimental results also allow the evaluation of the role played by magma viscosity in determining pluton geometries. In addition, a review of literature demonstrates a spatial and causal relationship between granites and thrusts and highlights the geometric control of magma pathways in the pluton final shape. The abundance of subhorizontal and tabular granitic intrusions indicates that the location of inflating granitic sills along thrust flats can be common. We argue that active and pre-existing flats-and-ramps thrusts provide a preferential continuous planar anisotropy susceptible to become a granitic magma migration pathway. 相似文献
3.
库车坳陷中段克拉苏构造带广泛发育盐相关收缩构造变形,总体具有"垂向叠置、分层变形"的整体挤压变形特征。沿东-西向克拉苏构造带不同区段深浅层构造变形样式、断层位移存在明显差异,北部盐下层由1～2条高角度基底卷入逆冲断层为主导,并在断层下盘发育捷径断层。区域结构平衡剖面和先存构造活动趋势分析结果表明,克拉苏构造带北侧变形属于基底卷入变形,早期先存断裂在后期收缩变形中重新活动,形成高角度的逆冲断裂。物理和数值砂箱模拟结果表明,盐岩层先于其上、下地层发生变形,其厚度、分布及边界条件差异是造成垂向分层收缩变形的主要控制因素。 相似文献
4.
Two Phases of Cenozoic Deformation in Northeastern Tibet: Thrusting Followed by Strike-Slip Faulting 总被引：1，自引：0，他引：1
TWO PHASES OF CENOZOIC DEFORMATION IN NORTHEASTERN TIBET: THRUSTING FOLLOWED BY STRIKE-SLIP FAULTING 相似文献
5.
More than 1400 km of two-dimensional seismic data were used to understand the geometries and structural evolution along the western margin of the Girardot Basin in the Upper Magdalena Valley. Horizons are calibrated against 50 wells and surface geological data (450 km of traverses). At the surface, low-angle dipping Miocene strata cover the central and eastern margins. The western margin is dominated by a series of en echelon synclines that expose Cretaceous–Oligocene strata. Most synclines are NNE–NE trending, whereas bounding thrusts are mainly NS oriented. Syncline margins are associated mostly with west-verging fold belts. These thrusts started deformation as early as the Eocene but were moderately to strongly reactivated during the Andean phase. The Girardot Basin fill records at least four stratigraphic sequences limited by unconformities. Several periods of structural deformation and uplifting and subsidence have affected the area. An early Tertiary deformation event is truncated by an Eocene unconformity along the western margin of the Girardot Basin. An Early Oligocene–Early Miocene folding and faulting event underlies the Miocene unconformity along the northern and eastern margin of the Girardot Basin. Finally, the Late Miocene–Pliocene Andean deformation folds and erodes the strata along the margins of the basin against the Central and Eastern Cordilleras. 相似文献
6.
塔里木盆地西部四十厂剖面志留系柯坪塔格组沥青砂岩沉积特征 总被引：2，自引：1，他引：1
塔里木盆地西部四十厂剖面志留系柯坪塔格组上部发育典型的沥青砂岩,分别位于若干个正韵律沉积旋回的中下部。通过典型露头剖面写实、沉积物粒度分析、矿物镜下鉴定、铸体薄片鉴定和X衍射等手段,对该剖面沥青砂岩进行了精细研究,发现沥青砂岩形成于潮坪沉积体系中潮间带下部的砂坪或混合坪内,岩性以细砂岩和粉砂岩为主,发育典型的双向交错层理和浅水动物遗迹等;其沉积物以跳跃搬运为主,受潮汐改造作用明显;碎屑矿物以石英或生物碎屑为主,含少量长石和粘土矿物。结合储层物性测试对沥青砂岩储集性进行了分析,结果表明,优质沥青砂岩储层往往是中等成分成熟度的长石石英砂岩,其内部长石含量在5%~10%之间,石英含量在75%~83%之间,其次是较高成分成熟度的石英砂岩,其内部长石含量一般在2%左右,石英含量在90%以上,较差的是含大量生物碎屑的砂岩,其内部生屑含量在60%左右,石英含量在35%左右。这对该区志留系沥青砂岩储层评价具有一定的借鉴意义。 相似文献
7.
Michael Denis M. Guiraud M. Konat�� J.-F. Buoncristiani 《International Journal of Earth Sciences》2010,99(6):1399-1425
Subglacial deformation is crucial to reconstructing glacier dynamics. Sediments associated with the Late Ordovician ice sheet
in the Djado Basin, Niger, exhibit detailed structures of the subglacial shear zone. Three main types of subglacial shear
zones (SSZ) are discriminated. The lowermost SSZ, developed on sandstones, displays Riedel macrostructures and cataclastic
microstructures. These resulted from brittle deformation associated with strong glacier/bed coupling and low pore-water pressure.
Where they developed on a clay-rich bed, the overlying SSZ display S–C to S–C′ fabrics, sheath folds, and dewatering structures.
These features indicate high ductile shear strain and water overpressure. On fine-grained sand beds, the SSZ exhibit homogenized
sand units with sand stringers, interpreted as fluidized sliding beds. The succession of subglacial deformation processes
depends on fluid-pressure behavior in relation to subglacial sediment permeability. Fluid overpressure allows subglacial sediment
shear strength and ice/bed coupling to be lowered, leading to ice streaming. 相似文献
8.
A thrust-fold belt consisting of a series of thrusts and buckling folds developed in the Mesozoic and Cenozoic strata within the Kuqa Depression, Tarim Basin. In this study, a structural interpretation model of the Kuqa Depression is established and the Mesozoic proto-basin is reconstructed on the basis of outcrop geology along the basin margin, seismic,well-log and CEMP data. The model is called ‘delaminate contractional deformation’, which emphasizes the decoupling between the Cenozoic, Mesozo... 相似文献
9.
砂岩侵入体是指深水沉积砂体受到外界的触发,并在一定条件下形成超压,致使上覆弱渗透性沉积物等围岩发生破裂,砂体以流化和液化的形式向周围沉积物产生侵入。砂岩侵入体的形成过程为形成超压、盖层破裂、产生液化和流化、发生侵入。差异压实、地震引发的液化、流体的加入和压力传递等多种因素都可以使砂岩中形成超压,当地层压力达到并超过破裂压力时,发生水力破裂,或地震引起上覆地层破裂,超压砂岩发生流化,侵入到低渗透围岩中。大量未固结的深水沉积砂岩、低-非渗透层的快速覆盖、形成超压的机制和触发事件是砂岩发生侵入的必备条件。 相似文献
10.
Field observations of highly porous and permeable sandstone in the Orange area (S-E Basin, France) show that networks of shear-enhanced compaction bands can form in a contractional regime at burial depths of about 400 m ± 100 m. These bands show equal compaction and shear displacements, are organized in conjugate and densely distributed networks, and are restricted to the coarse-grained (mean grain diameter of 0.6 ± 0.1 mm) and less porous (porosity of 26 ± 2%) sand layers. The bands are crush microbreccia with limited grain comminution and high grain microfracture density. They show reductions of permeability (mD) ranging from 0 to little more than 1 order of magnitude. They show no control on the alteration products related to meteoric water flow, which suggests that these shear-enhanced compaction bands have no or only negligible influence on subsurface fluid flow. Their selective occurrence and small (20%) reduction in transmissibility in densely populated layers prevented them from compartmentalizing the sandstone reservoirs. A comparison with compaction-band populations in the Navajo and Aztec sandtsones (western U.S.) emphasizes the role of burial depth and the presence of chemical compaction processes for the sealing potential of deformation bands. 相似文献
11.
准噶尔盆地腹部地区深埋储层物性特征及影响因素 总被引：1，自引：0，他引：1
准噶尔盆地腹部地区的储层埋深一般大于4 300 m,部分地区深度可达6 000 m左右,孔隙度和渗透率的大小变化范围也较大,弄清物性的主控因素有利于深埋储层的预测,为勘探提供依据.本文在前人研究和分析化验资料的基础上研究了该区深埋储层的物性,由于岩石类型多为岩屑砂岩,岩石成分含较多的塑性岩屑,因此强烈的压实作用极大的降低了准噶尔盆地腹部地区深埋储层的孔隙度,晚期的含铁碳酸盐岩胶结物使岩石更加致密.早期的碳酸盐岩胶结物因后期的有机酸和大气淡水的溶解作用产生了较多的次生溶蚀孔隙,晚期生烃导致的超压及早期油气充注对储层成岩过程中的成岩作用具有抑制作用,在一定程度上改善了深部储层物性,为深部油气的聚集提供了有利空间. 相似文献
12.
The structural history of the Hercynian Pyrenees is considered with respect to the relationships between the metamorphism and the successive deformations, the characteristics and mode of emplacement of the gneissic and anatectic cores of the metamorphic domes, the migmatization and the intrusions of plutonic and basic and ultrabasic rocks.The metamorphism can be shown to have progressed upwards with time, attaining the presently exposed levels just before, during and a short time after the major penetrative regional deformation.The intrusion of major plutonic, anatectic and gneissic massifs, which has determined the metamorphic domes in country rocks, was roughly synchronous with the progression of the metamorphism, but seems to have continued later in the uppermost levels.The basic and ultrabasic rocks uplifted by the intrusion of the anatectic cores of the metamorphic domes have been deformed and foliated by the major regional penetrative deformation, thus showing that their intrusion predated this deformation in the lowermost levels.These results, together with the presently available sedimentological data, lead us to propose a dynamic model of the tectonic evolution of the Hercynian Pyrenees.The first step was a crustal extension and thinning, attaining its maximum during Frasnian time, marked in the upper levels by a “ horst and graben” controlled sedimentation and in the lower crust by intrusions of basic magmas and the onset of the very low-pressure metamorphism and anatexis characteristic of the Hercynian Pyrenees.The second step was a crustal shortening marked by large-scale crustal thrusting followed by widespread regional penetrative deformation. The flysch troughs formed in front of the progressing and emerging thrusts. In lower levels, the thrusts are believed to have controlled the progressive ascent of the plutonic and anatectic magmas which continued their uplift and emplacement during major penetrative regional deformation in the actual mesozone and probably after it in the uppermost levels. 相似文献
13.
The Luning–Fencemaker fold-thrust belt (LFTB) of central Nevada reflects major Mesozoic shortening in the western US Cordillera, and involved contractional deformation in Triassic and lower Jurassic back-arc basinal strata. Structural analyses in the Santa Rosa Range, in the northern LFTB, provide new insight into the evolution of this belt. Four phases of deformation are recognized in the Santa Rosa Range. D1 involved tight to isoclinal folding, cleavage development under low-grade metamorphic conditions, and reverse faulting. This deformation phase reflects NW–SE shortening of 55–70% in the Early and/or Middle Jurassic. D2 structures are similar in orientation to D1 but involved much less overall strain and are well developed only to the southeast. D2 appears to be related to thrusting along the eastern margin of the LFTB in the Middle and/or Late Jurassic. D3 deformation reflects very minor shortening (<5%) in a subvertical direction, and is tentatively interpreted to reflect stresses generated during initial intrusion of mid-Cretaceous plutons in the area. D4 deformation demonstrably occurred synchronously with emplacement of Cretaceous granitoids dated at 102 Ma (U–Pb zircon) based on syntectonic relations between D4 structures and thermal metamorphism associated with intrusion, and an upgrade in D4 strain in the thermally softened metamorphic aureoles of the intrusions. This last phase of deformation reflects minor regional NE–SW shortening, coupled with localized strain associated with pluton emplacement.Formation of the LFTB structural province was accomplished during the D1 and D2 phases of deformation, and most shortening occurred during the D1 event. This Jurassic deformation led to structural closure of the back-arc basin by top-to-the-SE tectonic transport and development of a largely ductile fold-thrust belt. Subsequent deformation (D3 and D4) is >50 m.y. younger and unrelated to development of the LFTB. The younger deformation reflects a combination of minor regional shortening, interpreted to be related to the Cretaceous Sevier orogeny, plus localized shortening related to emplacement of Cretaceous intrusions. 相似文献
14.
From the early Late Permian onwards, the northeastern part of the Sydney Basin, New South Wales, (encompassing the Hunter Coalfield) developed as a foreland basin to the rising New England Orogen lying to the east and northeast. Structurally, Permian rocks in the Hunter Coalfield lie in the frontal part of a foreland fold‐thrust belt that propagated westwards from the adjacent New England Orogen. Thrust faults and folds are common in the inner part of the Sydney Basin. Small‐scale thrusts are restricted to individual stratigraphic units (with a major ‘upper decollement horizon’ occurring in the mechanically weak Mulbring Siltstone), but major thrusts are inferred to sole into a floor thrust at a poorly constrained depth of approximately 3 km. Folds appear to have formed mainly as hangingwall anticlines above these splaying thrust faults. Other folds formed as flat‐topped anticlines developed above ramps in that floor thrust, as intervening synclines ahead of such ramp anticlines, or as decollement folds. These contractional structures were overprinted by extensional faults developed during compressional deformation or afterwards during post‐thrusting relaxation and/or subsequent extension. The southern part of the Hunter Coalfield (and the Newcastle Coalfield to the east) occupies a structural recess in the western margin of the New England Orogen and its offshore continuation, the Currarong Orogen. Rocks in this recess underwent a two‐stage deformation history. West‐northwest‐trending stage one structures such as the southern part of the Hunter Thrust and the Hunter River Transverse Zone (a reactivated syndepositional transfer fault) developed in response to maximum regional compression from the east‐northeast. These were followed by stage two folds and thrusts oriented north‐south and developed from maximum compression oriented east‐west. The Hunter Thrust itself was folded by these later folds, and the Hunter River Transverse Zone underwent strike‐slip reactivation. 相似文献
15.
The geometry of several thrust-related folds in the Central Apennines of Italy results from a switch in deformation regime, from extension to contraction. This switch in tectonic regime occurred during the deposition of syn-orogenic sediments, and the emplacement and migration of the thrust belt–foredeep system towards the foreland in Neogene time. The styles of positive tectonic inversion result from normal faults that were steepened, rotated and truncated by thrusts, with local development of minor folds due to buttressing. Normal fault-controlled escarpments are also locally preserved in the forelimbs and backlimbs of thrust-related anticlines. The location and amplitudes of contractional structures across the belt reflects the distribution of pre-thrusting normal faults within precursor syn-orogenic basins, a result that may improve our understanding of the evolution of Apennine, as well as other thrust belt–foredeep systems. 相似文献
16.
17.
The Qiongdongnan Basin is a strongly overpressured basin with the maximum pressure coefficient over 2.2. Two types of vertical overpressure configuration can be identified by electronic logs and mud pressure, based on the calibration with the test pressure. The first is a double overpressure configuration, in which the middle low overpressure zone divides the entire overpressure zone into two zones. The double overpressure configuration lies primarily in the western part of the basin. The second is a single overpressure configuration, in which overpressure increases with depth. The single overpressure configuration lies primarily in the eastern part of the basin. Distribution maps of the overpressure top and overpressure horizons show three important characteristics: (1) The distribution of the pressure coefficient is not uniform. There are many low overpressure zones against a background of high overpressure. (2) The pressure coefficient in the western area is greater than in the eastern area. The maximum pressure coefficient in the western area is greater than 2.2. (3) There is a low overpressure interval between the high overpressure zones in the western area. Based on the overpressure distribution, some important implications for hydrocarbon exploration can be drawn. In the Qiongdongnan Basin, it has been shown that normal pressure zones are favorable for hydrocarbon accumulation, and strongly overpressured zones (pressure coefficient greater than 1.8) are unfavorable for hydrocarbon accumulation. Accordingly, the NW low overpressure belt around wells R, Q and S should be beneficial for hydrocarbon accumulations, and should be considered as the next exploration play in the Qiongdongnan Basin. Theoretical hydrofracture calculation and interpretation of the sand injectites indicate the presence of widespread hydrofractures in the basin. Comparison between the sealing capacities of the double overpressure and single overpressure configurations shows that the former is superior for hydrocarbon accumulation and preservation. Because of the strong sealing capacity provided by the displacement pressure and pore pressure difference between the seal rock and reservoir in the double overpressure configuration zone, hydrocarbons barely penetrate the seal rock in the middle low overpressure zone. Therefore, the exploration interval should be within and below the middle low overpressure zone in the western basin. 相似文献
18.
Fluid overpressure at the base of low-permeability strata reduces effective stress, allowing for gravitational sliding of the overlying cover. The force driving sliding is the slope-parallel component of the weight of the cover, whereas the resisting forces are the friction at the base of the cover and the buttressing resistance to shortening, which can be critically reduced by incision at the base of the slope. We developed an analytical model and undertook a series of analogue experiments to better understand the evolution of a sedimentary cover sliding above a low-permeability layer subjected to fluid overpressure. Where a downslope buttress was present, the sliding sheet length decreased with increasing pore-fluid pressure. In the absence of such buttress, the slide's length increased exponentially with increasing pore-fluid pressure. Another important difference dealt with geometry and kinematics. Buttressed slides consisted of one large slope-parallel mass rigidly translated and bounded by downslope thrusts and upslope normal faults. With increasing pore-fluid pressure, the contractional structures propagated upslope. By contrast, non-buttressed slides showed intense strain: deformation started with normal faults forming near the incision, then propagating upslope throughout the slide's evolution. 相似文献
19.
Yang Chu Michel Faure Wei Lin Qingchen Wang Wenbin Ji 《International Journal of Earth Sciences》2012,101(8):2125-2150
In orogenic belts, a basal décollement zone often develops at depth to accommodate the shortening due to folding and thrusting of the sedimentary cover. In the Early Mesozoic intracontinental Xuefengshan Belt of South China, such a décollement zone is exposed in the core of anticlines formed by the emplacement of the late-orogenic granitic plutons. Our detailed, multi-scale structural analysis documents a synmetamorphic ductile deformation. In the basal décollement, the Neoproterozoic pelite and sandstone, and the intruding Early Paleozoic granites were deformed and metamorphosed into mylonites and orthogneiss, respectively. The metamorphic foliation contains a NW–SE stretching lineation associated with top-to-the-NW kinematic indicators. The ductile shearing of these high-strained rocks can be correlated with NW-verging folds and thrusts recognized in the Neoproterozoic to Early Triassic sedimentary cover. Monazite U–Th–Pbtot chemical dating, and zircon SIMS U–Pb dating provide age constraints of the ductile shearing between 243 and 226?Ma, and late-orogenic granite emplacement around 235–215?Ma. In agreement with recent geochronological data, these new results show that the Xuefengshan Belt is an Early Mesozoic orogen dominated by the NW-directed shearing and thrusting. At the southeastern boundary of the Xuefengshan Belt, the Chenzhou-Linwu fault separates the Early Mesozoic domain to the NW from the Early Paleozoic domain to the SE. The tectonic architecture of this belt was possibly originated from the continental underthrusting to the SE of the South China block in response to northwest-directed subduction of the Paleo-Pacific plate. 相似文献
20.
A new structural evolution consisting of both extensional and contractional events has been defined for the St Ives Goldfield in the south-central Kalgoorlie Terrane of the eastern Yilgarn Craton in Western Australia. These events shaped the development of the fault architecture, which controlled the location of the regional anticlines, the magmatic centres, and the deposition of the Archaean greenstone successions. The fundamental grain of the St Ives Goldfield is north-northwest-trending. This trend is marked by faults which developed during D1 extension, which was oriented east-northeast–west-southwest. Across these faults we map major stratigraphic changes in the thickness and composition of units, especially of the previously undivided Black Flag Group volcaniclastic rocks. The centre of the St Ives Goldfield is dominated by the Kambalda Anticline. This north-northwest-trending regional fold was likely established early during the D1 extensional history, and was fully established during subsequent east-northeast-oriented D2 contraction. The regional anticline is an important architectural element because (1) magmatism and gold mineralising fluids were focussed into this domed region, and (2) deformation was partitioned across the limbs and crest of this structure. The D3 event involved regional uplift and extension, resulting in the formation of late basins (Merougil Conglomerate locally) and the emplacement of granitoids sourced from a metasomatised mantle wedge (Mafic-type porphyries). The most significant gold event in terms of endowment occurred during D4b sinistral strike-slip shearing and associated thrusting (e.g., Tramways and Republican thrusts). These thrusts were previously interpreted as the first contractional structures to deform the area (‘D1’), but are here reinterpreted as relatively late (D4b). In this D4b event, the north-northwest-trending faults underwent sinistral strike-slip shearing and were linked across the Kambalda Anticline by accommodation structures represented by generally east- to east-northeast-trending thrusts. Reactivation of D1 transfer structures may have influenced the location of these later accommodation structures. Late-stage mineralisation during D5 was the result of dextral strike-slip brittle shearing. 相似文献