The geometry of listric normal faults and deformation in their hangingwalls

In cross-sections containing listric extensional faults, area balancing techniques for depth to décollement are usually based on either bed length conservation or displacement conservation. Listric fault geometry may be constructed from a hangingwall roll-over profile using the ‘Chevron construction’. This construction, based on conservation of heave, necessitates a reduction in fault displacement with decreasing fault dip. A modification of this construction utilizing conservation of fault displacement predicts a listric fault that detaches at a shallower depth. A new construction based on slip lines uses fault-perpendicular displacement segments to generate listric fault shape. Fault propagation strain may be responsible for anomalous hangingwall geometries, and these can be predicted by forward modelling using either a modified Chevron construction or a slip-line construction.     

Extrusion vs. accretion at the frictional–viscous décollement transition in experimental thrust wedges: the role of convergence velocity

In many cases, thrust wedges accreted at shallow crustal levels show an across‐strike rheological variability along the basal décollement, notably from brittle to ductile behaviour. In this paper, we illustrate the results of sandbox analogue modelling research devoted to studying the influence of convergence velocity on wedge architecture when laterally juxtaposed frictional and viscous materials occur along the basal décollement of accreting thrust wedges. Our results show that slow convergence favours a near symmetrical distribution of thrust vergence within wedge sectors accreted above viscous décollement material, whereas fast convergence favours vergence asymmetry. In particular, at fast convergence rates the hinterlandward extrusion of viscous décollement material at the toe of the frictional wedge is favoured and contributed to accommodate a significant amount of the total contraction. Terra Nova, 18, 241–247, 2006     

准噶尔盆地南缘褶皱-逆冲断层带分析

讨论了与准噶尔盆地南缘褶皱-逆冲断层带有关的4个问题。(1)准噶尔盆地南缘褶皱-逆冲断层带具有纵向分带、横向分段和垂向构造分层的特征:纵向上由南至北可分为逆冲推覆构造带、基底卷入褶皱-冲断带和滑脱型褶皱-冲断带三个带;横向上,基底卷入褶皱-冲断带从西至东按横向调节带分为5个段,构造特征表现为反冲断层从不发育到向南反冲的位移逐渐增大、反冲断层所滑脱的层位亦逐渐加深;滑脱型褶皱-冲断带以红车断裂为界划分为西段和东段,西段构造运动弱,构造变形具双层结构;东段构造运动较强,发育大型冲向后陆的反向逆冲断层,构造变形多具有3层结构。(2)逆冲断层-褶皱类型按其形成机制分为基底卷入型冲断-褶皱、滑脱型冲断-褶皱以及基底卷入-滑脱混合型冲断-褶皱3大类,其中,基底卷入型冲断-褶皱的特征是褶皱作用发生在逆冲断裂之前,而滑脱型冲断-褶皱以冲断和褶皱同时或冲断层先于褶皱形成为特征。(3)本区存在横向和纵向传递带。横向调节带一般分布于基底卷入型褶皱-冲断带,主要为左旋走滑断层;纵向传递带分布于滑脱型褶皱-冲断带,以逆冲断层系斜列分布和位移纵向斜列传递为特征。(4)褶皱-冲断带形成的主控因素主要有:近南北向的水平挤压作用,上新世末—早更新世末和晚侏罗世末发生的构造变形以及古近系、下白垩统和下—中侏罗统发育的三套异常高压泥岩层相关的滑脱作用。     

下刚果盆地重力滑脱构造发育特征及演化规律

论述了西非被动大陆边缘下刚果盆地重力滑脱构造的发育特征及演化规律。下刚果盆地早白垩世至今的被动大陆边缘阶段主要发育重力滑脱构造,可分为上陆坡的重力滑脱伸展构造、中陆坡和下陆坡的重力滑脱底辟构造、下陆坡-深海平原转换区的重力滑脱冲断构造。一期完整的重力滑脱构造演化模式为从早到晚由陆向海逐渐发育的前展式发育模式,即最早发育高部位的重力滑脱伸展构造、其次发育中部的重力滑脱底辟构造、最后发育低部位的重力滑脱冲断构造。下刚果盆地总共发育两期重力滑脱构造,分别是早白垩世阿尔布期(Albian)-渐新世的第一期(早期)重力滑脱构造,中新世至今的第二期(晚期)重力滑脱构造。这两期重力滑脱构造之间呈现出从早到晚由陆向海发育的前展式结构,即晚期的重力滑脱构造位于早期重力滑脱构造的向海一侧。     

Deciphering thrust fault nucleation and propagation and the importance of footwall synclines

In this paper, we analyze small scale examples of thrust faults and related folding in outcrops of the Cretaceous Boquillas Formation within Big Bend National Park in west Texas to develop detailed understanding of the fault nucleation and propagation that may aid in the interpretation of larger thrust system structure. Thrust faults in the outcrop have maximum displacements ranging from 0.5 cm to 9 cm within competent limestone beds, and these displacements diminish both upward into anticlines and downward into synclines within the interbedded and weaker mudrock layers. We interpret the faults as having nucleated within the competent units and partially propagated into the less competent units without developing floor or roof thrusts. Faults that continued to propagate resulted in hanging wall anticlines above upwardly propagating fault tips, and footwall synclines beneath downwardly propagating fault tips. The observed structural style may provide insights in the nucleation of faults at the formation scale and the structural development at the mountain-range scale. Décollement or detachment layers may be a consequence rather than cause of thrust ramps through competent units and could be over interpreted from seismic data.     

The influence of pre-existing structure on the growth of syn-sedimentary normal faults in a deltaic setting,Niger Delta

Three dimensional seismic-reflection data from the western Niger Delta were used to investigate the segmentation and linkage of a syn-sedimentary normal fault array and to estimate the influence of a pre-existing normal fault on the geometry and growth of younger faults. The nucleation, growth and linkage of a regional (seaward-dipping) deltaic fault system were analyzed on reflectivity time-/horizon slices and vertical seismic sections. In the deep subsurface, a master fault that consists of two segments (northwestern, NW, and southeastern, SE) grew through time into a single fault by lateral tip propagation reaching a final length of about 15 km. After attaining this length, displacement along the fault system developed non-uniformly through time. The analysis of the hanging-wall sediments of the deep-seated master fault shows two different processes of vertical linkage above the NW and SE segment. The SE segment links vertically to several younger faults contemporaneously with displacement accumulation on the master fault; in contrast, fault linkage above the NW segment occurred only after an interval of master-fault inactivity connecting the deep-seated structure upwards to a single syn-sedimentary normal fault. The observed differences in fault development suggest that although multi-segment deltaic faults form single fault systems after segment linkage, individual pre-linkage characteristics can be preserved, supporting a possibly diverse upward growth and connection to younger faults in the overburden. The geological interpretations presented highlight the influence of large deep-rooted structures on the development, location and geometry of shallow deltaic faults, documenting the influence of an older structural grain on delta tectonics.     

Large-scale fluid infiltration, metasomatism and re-equilibration of Archaean basement granulites during Palaeoproterozoic thrust belt construction, Ungava Orogen, Canada

Abstract The metamorphic history of the Archaean Superior Province crystalline basement in the Palaeoproterozoic Ungava Orogen attests to the importance of structural and geohydrological controls on a retrograde amphibolite-granulite transition. Two distinct metamorphic suites, separated in age by nearly one billion years, are recognized in extensively exposed tonalitic to dioritic metaplutonic gneisses. The older suite comprises c. 2.7-Ga granulite facies assemblages (orthopyroxene-clinopyroxene-hornblende-plagioclase-ilmenite ± biotite ± quartz) that record moderate pressures (±5 kbar) and high temperatures (±800° C). A younger, c. 1.8-Ga suite resulted from amphibolitization of the granulites and is characterized by regionally extensive amphibolite facies mineral zones that broadly parallel the basal décollement of the overlying Proterozoic Cape Smith Thrust Belt. Deformation/mineral growth relationships in the amphibolitized basement indicate that extensive hydration and re-equilibration of the Archaean granulites occurred during thrust belt deformation. The transition from granulite facies to amphibolite facies assemblages is characterized by the growth of garnet-hornblende-quartz ° Cummingtonite coronas between plagioclase and orthopyroxene-clinopyroxene, as well as titanite coronas on ilmenite. Multi-equilibrium thermobarometry on the coronitic assemblages documents re-equilibration of the granulitic gneiss to 7.7 kbar at 644° C in the south and 9.8 kbar at 700° C in the north. The variably deformed, amphibolite facies domain sandwiched between the coronitic garnet zone and the basal décollement is marked by significant metasomatic changes in major element concentrations within tonalite. These changes are compatible with equilibrium flow of an aqueous-chloride fluid down a temperature gradient. The source of fluids for basement hydration/metasomatism is interpreted to be dehydrating clastic rocks in the overlying thrust belt, with fluid flow probably focused along the basal décollement.     

伸展盆地区断裂构造特征与成因

近十年来断裂构造研究进展迅速，研究思路发生了重大转变，强调应变与应力在断裂形成过程中的同等重要性。重点论述了断裂位移特征及影响因素，断裂位移在断层中部最大，端部最小至零，具有与断层规模无关的特征，但它受断裂分段、连接、近端过程等影响而发生变化。位移作为应变的结果，控制着横向褶皱的形成和分布、沉积中心的迁移(断裂单侧扩展时)或沉积位置不变但范围扩大(断裂双侧扩展时)以及沉积充填结构等。探讨了断裂三维几何形态分类及断裂形成与形态的控制因素：深部与浅部耦合(基底构造的活化与沉积盖层的响应)，建造与改造的耦合，边界条件与构造应力场，沉积压实和埋藏作用等。提出了断裂分级和组合规律，总体上伸展区断裂可分五级，一级控盆，二级控坳，三级控带，四级控圈，五级复杂化；不同级别的断裂三维组合规律可分为软连接组合和硬连接组合。伸展区断裂生长史可划分为成核、扩展、释压、连接、消亡和活化6个阶段。     

乌鲁木齐山前坳陷逆断裂-褶皱带及其形成机制

乌鲁木齐山前坳陷位于天山新生代再生造山带北侧,南以准噶尔南缘断裂与天山相隔,内部发育了几排逆断裂 背斜带,每一排构造带又由多个逆断裂 背斜组成。最南的齐古逆断裂 背斜带形成于中生代末,其北的玛纳斯逆断裂背斜带包含霍尔果斯、玛纳斯和吐谷鲁逆断裂背斜,形成于上新世末、早更新世初,受上、下２ 个滑脱面和断坡的控制,形成上、下２ 个背斜。再向北的独山子逆断裂背斜带由独山子、哈拉安德和安集海逆断裂背斜组成,形成于早、中更新世之间,主逆断裂向下在８ ～９ ｋｍ 深处的侏罗系中变为近水平滑脱面。此外,在独山子和吐谷鲁背斜的西北和东北还分别发育有正在形成之中的西湖和呼图壁隆起。研究了这些逆断裂 背斜带的地表和深部的构造特征、二维和三维几何学及运动学后指出,它们是在天山向准噶尔盆地扩展过程中发育于近水平滑脱面和不同断坡上的断展褶皱,独山子和安集海逆断裂 背斜的水平缩短量分别为２ ９００ ,１ ３５０ ｍ ,缩短速率分别为３９７ ,１８７ ｍ ｍ／ ａ。霍尔果斯、玛纳斯、吐谷鲁逆断裂 背斜的水平缩短量分别为５ ９００ ,６ ５００ ,６ ０００ ｍ ,相应的缩短速率分别为２０２,２２３ ,２０６ ｍ ｍ／ａ,准噶尔南缘断裂和乌鲁木齐山前坳陷第四纪?     

Fold development in the Jura

The term “folding” encompasses a wide range of processes, most of which are poorly understood. Jura folds, though comparatively simple, have developed by a superposition of different types of instabilities both in space and time. They are never periodic and sinusoidal and are more realistically approximated by kink bands with rounded hinges. Thrusting and kinking instabilities had closely similar thresholds, with kinks usually following and deforming thrusts. An analysis of embryonic folds shows that instabilities in the sedimentary cover were initiated primarily at inherited flaws of the basal décollement layer. They thence spread upward, often following stratigraphically higher incompetent layers in secondary décollement and there nucleating secondary instabilities before reaching the surface (disharmonic folding). Embryonic folds thus are usually narrow, emanating from secondary décollement layers that are connected with the basal décollement zone by thrusts nucleated at inherited obstacles. These are eventually overcome, permitting basal décollement to coalesce with kinking instabilities that grow downward from nuclei in higher décollement intervals. In this way folds centered in the basal décollement layer, and consequently of normal width, may be superposed on the narrow embryonic folds. The sequence and importance of the different elements may vary from place to place to result in a vast catalog of fold shapes.     

Reactivated strike–slip faults: examples from north Cornwall, UK

Several strike–slip faults at Crackington Haven, UK show evidence of right-lateral movement with tip cracks and dilatational jogs, which have been reactivated by left-lateral strike–slip movement. Evidence for reactivation includes two slickenside striae on a single fault surface, two groups of tip cracks with different orientations and very low displacement gradients or negative (left-lateral) displacements at fault tips.

Evidence for the relative age of the two strike–slip movements is (1) the first formed tip cracks associated with right-lateral slip are deformed, whereas the tip cracks formed during left-lateral slip show no deformation; (2) some of the tip cracks associated with right-lateral movement show left-lateral reactivation; and (3) left-lateral displacement is commonly recorded at the tips of dominantly right-lateral faults.

The orientation of the tip cracks to the main fault is 30–70° clockwise for right-lateral slip, and 20–40° counter-clockwise for left-lateral slip. The structure formed by this process of strike–slip reactivation is termed a “tree structure” because it is similar to a tree with branches. The angular difference between these two groups of tip cracks could be interpreted as due to different stress distribution (e.g., transtensional/transpressional, near-field or far-field stress), different fracture modes or fractures utilizing pre-existing planes of weakness.

Most of the d–x profiles have similar patterns, which show low or negative displacement at the segment fault tips. Although the d–x profiles are complicated by fault segments and reactivation, they provide clear evidence for reactivation. Profiles that experienced two opposite slip movements show various shapes depending on the amount of displacement and the slip sequence. For a larger slip followed by a smaller slip with opposite sense, the profile would be expected to record very low or reverse displacement at fault tips due to late-stage tip propagation. Whereas for a smaller slip followed by larger slip with opposite sense, the d–x profile would be flatter with no reverse displacement at the tips. Reactivation also decreases the ratio of d_max/L since for an original right-lateral fault, left lateral reactivation will reduce the net displacement (d_max) along a fault and increase the fault length (L).

Finally we compare Crackington Haven faults with these in the Atacama system of northern Chile. The Salar Grande Fault (SGF) formed as a left-lateral fault with large displacement in its central region. Later right-lateral reactivation is preserved at the fault tips and at the smaller sub-parallel Cerro Chuculay Fault. These faults resemble those seen at Crackington Haven.     

Geological evolution and structural style of the Palaeozoic Tafilalt sub‐basin,eastern Anti‐Atlas (Morocco,North Africa)

The Tafilalt is one of a number of generally unexplored sub‐basins in the eastern Anti‐Atlas of Morocco, all of which probably underwent a similar tectono‐stratigraphic evolution during the Palaeozoic Era. Analysis of over 1000 km of 2‐D seismic reflection profiles, with the interpretation of ten regional seismic sections and five isopach and isobath maps, suggests a multi‐phase deformation history for the Palaeozoic‐aged Tafilalt sub‐basins. Extensional phases were probably initiated in the Cambrian, followed by uniform thermal subsidence up to at least the end of the Silurian. Major extension and subsidence did not begin prior to Middle/Upper Devonian times. Extensional movements on the major faults bounding the basin to the north and to the south took place in synchronisation with Upper Devonian sedimentation, which provides the thickest part of the sedimentary sequence in the basin. The onset of the compressional phase in Carboniferous times is indicated by reflectors in the Carboniferous sequence progressively onlapping onto the Upper Devonian sequence. This period of compression developed folds and faults in the Upper Palaeozoic‐aged strata, producing a structural style characteristic of thin‐skinned fold and thrust belts. The Late Palaeozoic units are detached over a regional décollement with a northward tectonic vergence. The folds have been formed by the process of fault‐propagation folding related to the thrust imbricates that ramp up‐section from the décollement. Copyright © 2007 John Wiley & Sons, Ltd.     

陕甘川邻接区基于MAPGIS的金成矿远景区预测

陕甘川邻接区金矿床的展布与滑脱挤出构造、特别是不均匀滑脱关系非常密切。为了定量分析不均匀滑脱与金矿的关系 ,专门研制了自动追踪断裂求取弧形滑脱断裂曲率的计算机软件。经MAPGIS空间分析和多次实验证实 ,区内大中型以上金矿与曲率大于 4的点的密度区关系密切。用Grsip软件 ,对研究区进行断裂密度统计 ,再与金矿床进行MAPGIS空间分析 ,发现断裂密度在 10 0 2 40时 ,对金矿最有利。将研究区的印支—燕山期岩体依出露面积大小划分了大、中、小岩体和岩脉 4种规模的侵入岩。对侵入岩与金矿床MAPGIS空间分析 ,得出了中、小型岩体和岩脉的成矿有利区间分别为岩体边界向外扩展 70 ,6 0和 40个MAPGIS单位的环带。在进行MAPGIS空间分析过程中 ,还分析出研究区的金矿与该区应力异常区也有密切关系 ,但金矿与地层的关系不密切。最后 ,利用MAPGIS空间分析工具对陕甘川邻接区以上金成矿有利因素进行相交分析 ,圈定出 14个一级金矿远景区 ,19个二级金矿远景区和 11个三级金矿远景区。     

Three-dimensional modelling of folds,thrusts, and strike-slip faults in the area of Val de Ruz (Jura Mountains,Switzerland)

The Val-de-Ruz syncline is a northeast-southwest trending, rhomb-shaped synclinal basin in the internal part of the central Jura Mountains. The Mesozoic sediment succession is decoupled from the basement by a décollement horizon in Middle Triassic evaporite-bearing layers at depth and folding is associated with southeast-dipping thrust splays rooting into this décollement. The folds and thrusts also interfere with a system of N-S striking, sinistral strike-slip faults. A 3D model was constructed from the following input data: A digital elevation model, the 1:25,000 geological map of Switzerland, published contours of the top of basement based on drilling and seismics, and nine newly constructed cross-sections. The latter are based on surface geology and published seismic data. Cross-sections parallel to the northwestward transport direction, i.e. perpendicular to the overall strike, are line balanced. Anticlines are interpreted as faulted detachment folds, which initiated by buckling and associated flow of evaporites from synclinal to anticlinal areas. Anticlines were later broken by northwest-vergent thrusts and subsequently developed into fault-propagation folds during décollement from the basement and northwestward translation. The model assumes no faulting in the pre-Mesozoic basement and no hidden flat-ramp tectonics in the subsurface in order to account for structurally high positions. As a consequence, the modelled cumulative, post-deformation thickness of Triassic strata locally exceeds 1500 m, which we find in accordance with regional observations. From the geological 3D model, new cross-sections in any desired orientation and tectonic thickness variations of the layers can be extracted. The three output cross-sections presented are in excellent agreement with published reflection seismic data. The most important features of our model are (1) large thickness variations due to lateral flow of evaporites, and (2) new and plausible explanation of structural highs in terms of accumulation of Triassic strata by lateral flow.     

Spatial arrangement of décollements as a control on the development of thrust faults

We used two-dimensional finite element models to explore different configurations of weak layers in undeformed sedimentary sequences to investigate the occurrence of three characteristic types of thrust configurations: ramp-flat; imbricate; and duplex. In our models, we embedded two low-friction weak layers with a finite spatial extent in a sequence of stronger rock. These two weak layers were initially horizontal, were separated vertically by 1 km, and were arranged in three different relative positions to each other. When the models were deformed and these weak layers developed into décollements, they interacted to produce one of the three types of thrust faults as a function of their initial configurations. When the tips of weak layers were separated by a large gap (>10 km), only the lower-level décollement became active, producing imbricate thrusts. When the two weak layers overlapped for a large distance (>10 km), they simultaneously became active décollements, producing duplexes in the overlapped zone. When the gap or overlap was small (<5 km), the two weak layers also simultaneously became active décollements but their tips linked up to form a ramp-flat geometry. These results suggest that thrust geometry is highly sensitive to the initial arrangement of décollements.     

Polyphase late Palaeozoic deformation in the southeastern foreland and northwestern Piedmont of the Alabama Appalachians

Late Palaeozoic deformation in the southern Appalachians is believed to be related to the collisional events that formed Pangaea. The Appalachian foreland fold and thrust belt in Alabama is a region of thin-skinned deformed Palaeozoic sedimentary rocks ranging in age from Early Cambrian to Late Carboniferous, bounded to the northwest by relatively undeformed rocks of the Appalachian Plateau and to the southeast by crystalline thrust sheets containing metasedimentary and metaigneous rocks ranging in age from late Precambrian to Early Devonian. A late Palaeozoic kinematic sequence derived for a part of this region indicates complex spatial and temporal relationships between folding, thrusting, and tectonic level of décollement. Earliest recognized (Carboniferous(?) or younger) compressional deformation in the foreland, observable within the southernmost thrust sheets in the foreland, is a set of large-scale, tight to isoclinal upright folds which preceded thrafing, and may represent the initial wave of compression in the foreland. Stage 2 involved emplacement of low-angle far-traveled thrust sheets which cut Lower Carboniferous rocks and cut progressively to lower tectonic levels to the southwest, terminating with arrival onto the foreland rocks of a low-grade crystalline nappe. Stage 3 involved redeformation of the stage 2 nappe pile by large-scale upright folds oriented approximately parallel to the former thrusts and believed to be related to ramping or imbrication from a deeper décollement in the foreland rocks below. Stage 4 involved renewed low-angle thrusting within the Piedmont rocks, emplacement of a high-grade metamorphic thrust sheet, and decapitation of stage 3 folds. Stage 5 is represented by large-scale cross-folding at a high angle to previous thrust boundaries and fold phases, and may be related to ramping or imbrication on deep décollements within the now mostly buried Ouachita orogen thrust belt to the southwest. Superposed upon these folds are stage 6 high-angle thrust faults with Appalachian trends representing the youngest (Late Carboniferous or younger, structures in the kinematic sequence.     

Strain compatibility and fault linkage in relay zones on normal faults

Relay zones on normal faults are unlikely to have tabular geometries as depicted in idealised models. Rotation of a relay ramp between non-parallel and non-planar relay-bounding faults will inevitably lead to strain compatibility problems causing open gaps or overlaps within the relay zone. Linkage of relay-bounding faults does not evolve from a single branch point. Rather, linkage occurs at multiple points along the fault tip lines giving rise to initially discontinuous branch lines. Where linkage occurs along a discontinuous slip-aligned branch line, displacement at different levels within the relay zone is partitioned between variable amounts of ramp rotation and slip across the branch line. The linking fault propagates when strain compatibility can no longer be maintained by continuous deformation processes, such as thickening or thinning of incompetent layers within the relay ramp. Step-like changes in vertical displacement vs. distance (d − x) profiles on horizons containing apparently intact relay ramps are probably indicative of incipient breaching and can be used predict the presence of a slip-aligned branch line in the sub-surface. Despite the complexity of the strain distribution within relay zones, the total vertical displacement across the relay remains geometrically coherent at all levels.     

Listric growth faults in the Kenya Rift Valley

Many of the major faults in the Kenya Rift Valley are curved in section, were active over considerable periods and form sets which are related in space and time. They can, therefore, be regarded as systems of listric growth faults. The Elgeyo Fault marks the western limit of rift structures at this latitude and displaces the basement surface by up to about 6 km. The Kamasia Hills are a block rotated above this fault plane. Movement on the Elgeyo Fault has been grossly continuous since at least 16 Ma ago but deposition of volcanics and sediments has generally kept pace with the growth of the escarpment. The Kaparaina Arch is a rollover anticline on the downthrown side of the Saimo Fault on the eastern side of the Kamasia Hills. On the eastern side of the rift, the block between the Bogoria and Wasages-Marmanet Faults has shown continued rotation since about 15 Ma. The Pleistocene lavas on the rift floor here show rollover into the Bogoria Fault and have formed a facing near the top of the escarpment. Area balancing calculations suggest depths to décollement of 25 km for the Elgeyo Fault, 6 km for the Saimo Fault and 12 km for the Bogoria Fault. The most direct evidence for the listric nature of the faults is provided by microearthquakes near Lake Manyara which appear to lie on fault planes connected to surface escarpments.     

Differential Hydrocarbon Accumulation Controlled by Structural Styles along the Southern and Northern Tianshan Thrust Belt

The Kuqa and the Southern Junggar foreland thrust belts, which lie to the southern and northern Tianshan, respectively, were formed under a strong compressional tectonic setting. Due to the differential propagation and deformation under the control of the décollement horizon, the structural deformation styles differ in the Kuqa and Southern Junggar thrust belts. Imbricated stacking is developed in the Kuqa thrust belt, forming a piggyback imbricated pattern of faulted anticline and fault-block structural assemblage dominated by salt structures. In contrast, wedge-shaped thrusts are developed in Southern Junggar, mainly forming vertical laminated patterns of multi-wedge-structure stacks strongly influenced by the décollement horizons. The different deformation patterns and structural styles of the north and south of Tian Shan control the contrasting characteristics of hydrocarbon accumulation in the foreland thrust belts of the Kuqa and the Southern Junggar thrust belts, including the variance in the hydrocarbon trap types, pathway systems and hydrocarbon-bearing horizons. Proven by the hydrocarbon accumulation research and exploration achievements, recent exploration targets should focus on sub-salt piggyback imbricated structural patterns in the Kuqa and the deep laminated patterns in the Southern Junggar thrust belt.