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1.
Controls on low-pressure anatexis   总被引:2,自引:0,他引:2  
Low-pressure anatexis, whereby rocks melt in place after passing through the andalusite stability field, develops under more restricted conditions than does low-pressure metamorphism. Our thermal modelling and review of published work indicate that the following mechanisms, operating alone, may induce anatexis in typical pelitic rocks without inducing wholesale melting in the lower crust: (i) magmatic advection by pervasive flow; (ii) crustal-scale detachment faulting; and (iii) the presence of a high heat-producing layer. Of these, only magmatic advection by pervasive flow and crustal-scale detachment faulting have been shown quantitatively to provide sufficient heat to cause widespread melting. Combinations of the above mechanisms with pluton-scale magmatic advection, shear heating, removal of the lithospheric mantle, or with each other provide additional means of developing suitable high temperatures at shallow crustal levels to generate low-pressure anatexis.  相似文献   

2.
The purpose of this paper is to examine the kinematic behaviour of normal fault systems and see what general conditions govern their geometrical evolution. We pay particular attention to seismological and surface data from regions of present day active normal faulting, as the instantaneous three-dimensional geometry at the time of fault movement is better known in active regions than in areas where the faults are now static.Most normal faults are concave upward, or listric. This shape can be produced by geometric constraints, either because the faults reactivate curved thrusts, or because they must be curved to accommodate rotations. Another effect which will produce curved faults is the variation of rheology with depth: brittle failure at shallow depths produces less fault rotation than does distributed creep in the lower part of the crust. An important geometric feature of normal faulting is the uplift of the footwall. The amount of such uplift is related not only to the elastic properties of the lithosphere, but also to the throw and dip of the fault. A striking feature of active normal faults is that they occur in groups in which all the faults dip in the same direction. This behaviour arises because the faults cannot intersect: if they do, one must cease to be active. The rotation which such fault systems produce reduces the dip of the faults until a new steeply dipping fault is formed. Once a new fault cuts pre-existing faults the earlier faults become locked, and a new set of faults must propagate rapidly across the whole region involved. Many of these geometric constraints also apply to thrust faulting.  相似文献   

3.
Deep crustal extensional faulting in the Ivrea Zone of Northern Italy   总被引:1,自引:0,他引:1  
K.H. Brodie  E.H. Rutter 《Tectonophysics》1987,140(2-4):193-212
The Ivrea Zone in Northern Italy consists of amphibolite and granulite facies metasedimentary, metabasic, and ultrabasic rocks, and is thought to represent a section through the deep continental crust. Detailed mapping of the high grade part of this zone has revealed a series of high temperature shear zones, which, after the effects of later low temperature faulting and folding have been removed, appears to accommodate extension of the sequence. The shear zones formed at temperatures similar to those at which thermal equilibration occurred in the host rocks, and locally show evidence for development under prograde conditions. These observations fit well with thermal effects calculated from a simple heat flow model for extensional faulting. In this model the effects of shear heating and displacement of cool hanging-wall rocks against hotter footwall rocks are calculated.

These observations indicate that faulting as a mode of failure may be important during extension of the lower continental crust, especially when basic rocks are the dominant components of the rock pile. A restored section through the extended lower crust as observed in the Ivrea Zone is presented, and the extent to which the features observed are able to explain seismic reflectivity of the lower crust is discussed.  相似文献   


4.
塔里木盆地巴楚隆起古董山断裂带构造分析   总被引:3,自引:0,他引:3       下载免费PDF全文
古董山断裂构造带位于塔里木盆地西部的巴楚隆起上,走向北西-南东,延伸140 km左右。基于地震剖面的详细解释,识别出4期构造变形:寒武-奥陶纪正断层、二叠纪正断层、中新世冲断层、上新世-更新世冲断层及其伴生的正断层。中新世基底卷入型冲断层是古董山构造带的主控断裂构造,构成断裂带的主体,构造变形样式为断层传播褶皱。寒武-奥陶纪正断层形成复式地垒,隐伏于中新世主干断层之下。二叠纪正断层可能伴生有岩浆活动。先存的正断层和岩浆岩对古董山中新世断裂活动具有明显的控制作用;后期的断裂活动,即上新世-更新世逆冲断层和正断层,对中新世形成的断裂构造有改造作用。古董山断裂带东南端与玛扎塔格构造带西端交汇,但两者不是同一条断裂带。  相似文献   

5.
Finite element analysis of lithosphere deformation, incorporating failure criteria based on the Modified Griffith Theory for an elastic upper crust and a visco-elastic rheology for the lower crust and lithospheric mantle, demonstrates that normal faulting as a result of comparatively small, horizontal tensile stresses acting throughout the lithosphere can occur by the phenomenon of stress amplification. The use of a simple, Newtonian viscosity or of power law creep for the visco-elastic material does not significantly change the results. The time to failure is dependent upon the magnitude of the applied stress and the effective viscosity of the underlying material. For an applied stress of 20 MPa and a constant viscosity of 1023 Pa s failure is predicted after 1.19 Ma, with a fault plane hade of about 30°. A decrease of one order of magnitude in the viscosity of the lower crust results in a slightly shorter time to failure whereas an increase of one order of magnitude results in a very much greater failure time.  相似文献   

6.
扬子陆块西缘石棉大水沟岩片变形变质特征   总被引:2,自引:0,他引:2  
经近年研究,石棉大水沟岩片边界断裂为韧性剪切带,具逆冲-推覆性质,在中生代碰撞造山过程中逆冲叠置在扬子陆块之上。该岩片经历了晚二叠世裂谷变质、晚三叠世末至早中侏罗世滑脱-收缩动热变质和晚侏罗世热隆接触变质等三期主要变形、变质作用,尤其是后两期影响最深刻,奠定了现今热隆构造,并伴有赚矿床的形成。大水沟热隆,具陆陆碰撞地壳加厚,剪切增热,熔融岩浆底辟上隆的演化特点,属岩浆热隆。  相似文献   

7.
通过研究黄骅坳陷新生代的构造活动,对黄骅坳陷无机成因二氧化碳气藏的形成与分布特征进行分析,发现黄骅坳陷无机成因CO2成藏与断裂和岩浆活动密切相关。新生代的NE—NEE向的伸展断裂为幔源型二氧化碳提供了良好的通道,尤其是在这些NE—NEE向伸展断裂与NW向断裂的交汇处,有利于二氧化碳的运移和聚集;同时这些伸展断裂往往是地热较高的区域,有利于热变质成因二氧化碳的生成;岩浆作用不仅可以直接释放来自幔源的二氧化碳气体,而且岩浆作用带来的地热也可以促进碳酸盐岩的热变质作用,释放二氧化碳。同时,黄骅坳陷新生代断裂和岩浆活动的迁移性特点形成了无机成因二氧化碳气藏地域分布特征。  相似文献   

8.
The thermal impact of several kilometre-thick magmatic underplating in the lower continental crust is studied with analytical and numerical methods. Simple analytical solutions are derived for the thermal transient in the case of an infinite depth below the underplate and also for the case of a finite depth (down to the asthenosphere). It is shown that these solutions lead to simple approximations for when the transient surface heat flow is at its maximum, what the maximum is, and for how long the transient lasts. Even though these solutions assume that the underplate is emplaced instantaneously, they are useful in the interpretation of underplating over finite time spans. A numerical scheme is suggested for the modelling of underplating that handles both short time intervals as well as long intervals. The scheme treats magmatic underplating in a mass and energy conservative manner, and it is compared against the analytical solutions. Finally, the analytical and numerical results for thermal transients are applied to a transect from the Vøring margin (NE Atlantic), with respect to various degrees of early Cenozoic magmatic intrusion. It appears that more than half of the lower crustal body (LCB) in the Vøring margin must be magmatic underplating for the vitrinite reflectance to be substantially higher than for the non-magmatic case, where the LCB is assumed to comprise Caledonian crust.  相似文献   

9.
断层作用热模型及其对烃源岩热演化的影响   总被引:1,自引:0,他引:1  
从盆地的应力状态分析入手,从断层摩擦生热的角度,建立了断层作用生热的定量模型。在此基础上,确定了断层摩擦产生的热量与断层的性质、深度、构造应力和流体压力等之间的定量关系,定量分析了断层摩擦生热对烃源岩热演化的影响。结果表明:断层作用的生热量主要决定于断层的深度,构造应力的大小、流体压力、断层的位移量、断面摩擦系数等;断层的活动速率对断层摩擦的生热量没有影响,但对断层带内产生的温度却起决定性的作用;在断层快速活动的条件下(地震型),断层摩擦生热虽然可以产生很高的温度,可以造成断层面附近岩石的局部熔融,但其影响范围和影响持续的时间是十分有限的。   相似文献   

10.
The well-known Pliocene to Quaternary Rio Grande rift of northern New Mexico and southern Colorado is distinctly different from the Miocene rift, especially in structural style. Prior to approximately 21 Ma, there was little extension or rift-basin development. Uppermost Oligocene and Lower Miocene strata were deposited as broad volcaniclastic aprons, with no significant evidence of syn-depositional faulting, in contrast to younger deposits. The only documented areas of extensional faulting and stratal rotation older than 21 Ma occur within or close to magmatic centers. Early rift basins (21-10 Ma) developed as half grabens progressively tilted in hanging walls of normal faults that primarily reactivated Laramide (Eocene) reverse faults: (1) the San Luis basin tilted eastward as the Sangre de Cristo normal fault reactivated westward-dipping Laramide reverse faults; (2) the Tesuque basin tilted westward as normal faults reactivated eastward-dipping Laramide reverse faults of Sierra Nacimiento and related features; and (3) the Belen basin experienced complex tilting as diverse normal faults reactivated variably dipping Laramide reverse faults. Some of these early-rift faults remain active, whereas others became inactive starting near 10 Ma, as new faults broke across Laramide and early-rift features. The Embudo transfer zone linked normal faults along the east side of the San Luis basin to the Pajarito, La Bajada, San Francisco, and Rincon fault zones at this time. Normal faults along the northwest side of the Miocene Tesuque basin became inactive at the same time that rapid uplift of the Sandia Mountains as a footwall block began at about 10 Ma. This shifting of normal-fault activity resulted in reversal of tilt direction from westward for the Miocene Tesuque basin to eastward for the modern Albuquerque basin. Uplift and erosion of early-rift deposits along the northwest side of the Albuquerque basin have resulted.

This two-stage model for evolution of the Rio Grande rift in north-central New Mexico and southern Colorado is fundamentally different from previous two-stage models, which described Oligo-Miocene volcaniclastic aprons as “early rift deposits,” and related them to extensional structures. Rather, development of half grabens began around 21 Ma, with dominance of negative inversion of Laramide reverse and thrust faults. Regional change in extension direction led to the abandonment of some faults and the initiation of new faults at 10-8 Ma in the Rio Grande rift. The biggest change occurred in the Tesuque basin, as the western boundary fault became inactive during growth of the Jemez volcanic field, and the Sandia Mountains began their rapid rise as the northern Albuquerque basin tilted to the east. Continued regional uplift, and integration and incision of the Rio Grande and tributaries, have occurred during the last 5 million years, with the course of the river tending to follow the downdropped side of each modern half graben.  相似文献   

11.
The upper part of the High Himalayan slab in north central Nepal is comprised of a thick layer-parallel sheet of biotite + muscovite + tourmaline ± garnet ± sillimanite ± cordierite leucogranite up to 3–4 km thick and dipping north at 5–20°. These strongly peraluminous magmas were emplaced into high temperature–low-pressure sillimanite and cordierite bearing gneisses, calc-silicates and rare amphibolites which were metamorphosed at temperatures of 600–650°C some time during the Oligocene–early Miocene. Parallel stringers of black xenolithic gneisses within the leucogranites suggest passive magmatic intrusion along fractures parallel to the schistosity in the country rocks. In the mountains of Cho Oyu, Gyachung Kang, Pumori, Lingtren and the base of the Everest massif, these leucogranites form part of a single structural horizon bounded at the top by the Lhotse Detachment, the lower of two N-dipping normal faults of the South Tibetan Detachment (STD) system, and below by the Khumbu Thrust (KT), an out-of-sequence fault which was partly responsible for the uplift, erosion and exhumation of the leucogranites. A model for the emplacement of these leucogranites is proposed, where they represent viscous minimum melts, produced by melting of a pelitic protolith, similar to the underlying sillimanite grade gneisses, through muscovite breakdown, either during fluid-absent melting at <750°C, or fluid-saturated melting at <650°C. These leucogranites may have intruded up to ∼40 km horizontally from their source, but were emplaced by hydraulic fracturing along multiple sills into recently metamorphosed high temperature–low pressure rocks of the middle crust. The entire mid-crustal region where the granites were formed and emplaced was later uplifted along the hangingwall of the Khumbu Thrust, and by the structurally lower Main Central Thrust (MCT) to their present position. The location of the leucogranites at the top of the slab, but never intruding across the STD normal faults and the complete lack of leucogranites further down the slab rule out frictional heating along the MCT as a viable heat source and also rule out diapirism as a viable emplacement mechanism. High radioactivity of the crustal source, percolation of fluid from the migmatitic source into sills and dykes during simple shear, heat focussing due to a large thermal conductivity contrast across the STD, and decompression during active low-angle normal faulting above, are all viable processes to explain leucogranite melting and emplacement.  相似文献   

12.
Abstract: This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N-S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E-W or WNW-ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike-slip fault type earthquakes with strong compressive stress nearly in the NNE-SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based on seismo-tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N-S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N-S direction. The obstruction for the plateau to move eastward is rather weak.  相似文献   

13.
The Schlinig fault at the western border of theÖtztal nappe (Eastern Alps), previously interpreted as a west-directed thrust, actually represents a Late Cretaceous, top-SE to -ESE normal fault, as indicated by sense-of-shear criteria found within cataclasites and greenschist-facies mylonites. Normal faulting postdated and offset an earlier, Cretaceous-age, west-directed thrust at the base of theÖtztal nappe. Shape fabric and crystallographic preferred orientation in completely recrystallized quartz layers in a mylonite from the Schlinig fault record a combination of (1) top-east-southeast simple shear during Late Cretaceous normal faulting, and (2) later north-northeast-directed shortening during the Early Tertiary, also recorded by open folds on the outcrop and map scale. Offset of the basal thrust of theÖtztal nappe across the Schlinig fault indicates a normal displacement of 17 km. The fault was initiated with a dip angle of 10° to 15° (low-angle normal fault). Domino-style extension of the competent Late Triassic Hauptdolomit in the footwall was kinematically linked to normal faulting.

The Schlinig fault belongs to a system of east- to southeast-dipping normal faults which accommodated severe stretching of the Alpine orogen during the Late Cretaceous. The slip direction of extensional faults often parallels the direction of earlier thrusting (top-W to top-NW), only the slip sense is reversed and the normal faults are slightly steeper than the thrusts. In the western Austroalpine nappes, extension started at about 80 Ma and was coeval with subduction of Piemont-Ligurian oceanic lithosphere and continental fragments farther west. The extensional episode led to the formation of Austroalpine Gosau basins with fluviatile to deep-marine sediments. West-directed rollback of an east-dipping Piemont-Ligurian subduction zone is proposed to have caused this stretching in the upper plate.  相似文献   


14.
The geometry and architecture of a well exposed syn-rift normal fault array in the Suez rift is examined. At pre-rift level, the Nukhul fault consists of a single zone of intense deformation up to 10 m wide, with a significant monocline in the hanging wall and much more limited folding in the footwall. At syn-rift level, the fault zone is characterised by a single discrete fault zone less than 2 m wide, with damage zone faults up to approximately 200 m into the hanging wall, and with no significant monocline developed. The evolution of the fault from a buried structure with associated fault-propagation folding, to a surface-breaking structure with associated surface faulting, has led to enhanced bedding-parallel slip at lower levels that is absent at higher levels. Strain is enhanced at breached relay ramps and bends inherited from pre-existing structures that were reactivated during rifting. Damage zone faults observed within the pre-rift show ramp-flat geometries associated with contrast in competency of the layers cut and commonly contain zones of scaly shale or clay smear. Damage zone faults within the syn-rift are commonly very straight, and may be discrete fault planes with no visible fault rock at the scale of observation, or contain relatively thin and simple zones of scaly shale or gouge. The geometric and architectural evolution of the fault array is interpreted to be the result of (i) the evolution from distributed trishear deformation during upward propagation of buried fault tips to surface faulting after faults breach the surface; (ii) differences in deformation response between lithified pre-rift units that display high competence contrasts during deformation, and unlithified syn-rift units that display low competence contrasts during deformation, and; (iii) the history of segmentation, growth and linkage of the faults that make up the fault array. This has important implications for fluid flow in fault zones.  相似文献   

15.
Detailed 40Ar/39Ar geochronology on single grains of muscovite was performed in the Variscan Tanneron Massif (SE France) to determine the precise timing of the post-collisional exhumation processes. Thirty-two plateau ages, obtained on metamorphic and magmatic rocks sampled along an east–west transect through the massif, vary from 302 ± 2 to 321 ± 2 Ma, and reveal a heterogeneous exhumation of the lower crust that lasted about 20 Ma during late Carboniferous. In the eastern part of the massif, the closure of the K–Ar isotopic system is at 311–315 Ma, whereas in the middle part of the massif it closes earlier at 317–321 Ma. These cooling paths are likely to be the result of differential exhumation processes of distinct crustal blocks controlled by a major ductile fault, the La Moure fault that separates both domains. In the western part of the massif, the ages decrease from 318 to 303 Ma approaching the Rouet granite, which provides the youngest age at 303.6 ± 1.2 Ma. This age distribution can be explained by the occurrence of a thermal structure spatially associated to the magmatic complex. These ages argue in favour of a cooling of the magmatic body at around 15 Ma after the country rocks in the western Tanneron. The emplacement of the Rouet granite in the core of an antiform is responsible for recrystallization and post-isotopic closure disturbances of the K–Ar chronometer in the muscovite from the host rocks. These new 40Ar/39Ar ages clearly outline that at least two different processes may contribute to the exhumation of the lower crust in the later stage of collision. During the first stage between 320 and 310 Ma, the differential motion of tectonic blocks limited by ductile shear zones controls the post-collisional exhumation. This event could be related to orogen parallel shearing associated with crustal-scale strike-slip faults and regional folding. The final exhumation stages at around 300 Ma take place within the tectonic doming associated to magmatic intrusions in the core of antiformal structures. Local ductile to brittle normal faulting is coeval to Upper Carboniferous intracontinental basins opening.  相似文献   

16.
变质核杂岩与岩浆作用成因关系综述   总被引:12,自引:0,他引:12  
对岩浆与伸展作用的关系、伸展作用中岩浆的成因和需加强的工作进行了讨论,并重点论述了变质核杂岩形成机制与侵入作用的关系。在造山带重力势能差和深部作用等各种因素导致的拉伸应力场作用下,岩石圈地幔和地壳通过减压或深部热活动发生部分熔融而形成岩浆,岩浆的上涌强化了地壳伸展,对地壳的弱化作用触发伸展构造的发生。岩浆作用是变质核杂岩形成的主导因素之一,其主要包括对地壳的加热、弱化导致拆离断层的形成及由其浮力和密度产生不均一隆升而形成穹隆。  相似文献   

17.
地壳根、造山热与岩浆作用   总被引:8,自引:1,他引:7  
简要讨论了近年来造山带及其岩浆作用研究的主要进展。造山带流变学结构与造山热和岩浆作用有着密切的耦合关系。年轻的山带往往存在地壳根,但古老的山带地壳根是否存在,取决于造山带的热状态和榴辉岩化的强度,只有缺乏流体和冷的造山带才保留有地壳根,例如古生代的南乌拉尔山和北美前寒武纪的南Trans-Hudson造山带。造山带的伸展塌陷往往伴随着幔源岩浆底侵、地壳软化、隆升和强烈岩浆作用。由于地幔浮力和造山热的作用,一些山带具有高的海拔和薄而热的地壳,属于具有长期活动性的构造带。研究表明,这些具有长期活动性的构造带,是建立在以前形成的热的、软化了的弧后区内。中国昆仑—秦岭—大别造山系北缘,古生代时期发育了与俯冲有关的弧岩浆带,而南缘发育了相近时代的与弧后伸展有关的双峰式岩浆带,构成古生代双岩浆带。该造山系早中生代的造山作用,就是在南缘的古生代弧后岩浆带基础上发展起来的。因此,该双岩浆带提供了造山热控制复合造山作用的实例。  相似文献   

18.
Thermal anomalies in tectonically active areas are often attributed to sub-seafloor fluid circulation and faulting mechanisms, particularly in subduction zones where the largest thrust earthquakes occur. Postseismic fluid flow is enabled by the poroelastic response of the fault system to the earthquake's strain field, as well as by the rupturing of permeability barriers in the vicinity of the fault zone. We investigated the relative importance of these mechanisms on postseismic pore-pressure diffusion and advective heat transport in the subduction zone setting. A two-dimensional numerical fluid flow and heat transport model was developed for the Costa Rica subduction zone offshore of the Nicoya Peninsula. The flow and transport model was coupled with an earthquake strain model to quantify the effects of coseismic strain and permeability enhancement on fluid pressures and temperatures within the Costa Rica margin. Coseismic changes in pore pressure and postseismic pore-pressure diffusion were found to be sensitive to the compressibility of the porous medium, and patterns of pore-pressure recovery were more complex than that predicted by theoretical faulting models. Coseismic contraction and extension of the crust produced high fluid pressures close to the fault, while the inflow of fluid from depth increased fluid pressures several years following the simulated fault slip. Crustal deformation alone was not observed to perturb the temperature field. Laterally extensive permeability increases of two orders of magnitude along the décollement were required to produce small changes in heat flow. Local permeability changes in the upper slope region of least five orders of magnitude were necessary to noticeably affect heat flow. The results of the numerical simulations may help to refine conceptual faulting models and provide guidance for locating long-term hydrologic monitoring sites at Costa Rica and other subduction zones.  相似文献   

19.
Analysis of fault system in the high-P/T type Sambagawa metamorphic rocks of central Shikoku, southwest Japan, shows that conjugate normal faults pervasively developed in the highest-grade biotite zone (upper structural level) in three study areas (Asemi river, Oriu and Niihama areas). These conjugate normal faults consist of NE–SW to E–W striking and moderately north-dipping (set A), and NNW–SSE striking and moderately east dipping (set B) faults. The fault set A is dominant compared to the fault set B, and hence most of deformation is accommodated by the fault set A, leading to non-coaxial deformation. The sense of shear is inferred to be a top-to-the-WNW to NNW, based on the orientations of striation or quartz slickenfibre and dominant north-side down normal displacement. These transport direction by normal faulting is significantly different from that at D1 penetrative ductile flow (i.e. top-to-the-W to WNW). It has also been found that these conjugate normal faults are openly folded during the D3 phase about the axes trending NW–SE to E–W and plunging west at low-angles or horizontally, indicating that normal faulting occurred at the D2 phase. D2 normal faults, along which actinolite breccia derived from serpentinite by metasomatism sometimes occurs, perhaps formed under subgreenschist conditions (ca. 250 °C) in relation to the final exhumation of Sambagawa metamorphic rocks into the upper crustal level. The pervasive development of D2 normal faults in the upper structural level suggests that the final exhumation of Sambagawa metamorphic rocks could be caused by “distributed extension and normal faulting (removal of overburden)” in the upper crust.  相似文献   

20.
刘健  史杰  姚鑫  李钦  常志勇 《中国地质》2018,45(4):681-692
帕米尔东北缘位于青藏高原西北部,是新构造运动最强烈的地区之一。受控于公格尔拉张断裂作用的塔什库尔干盆地,活动构造强烈,高的大地热流值和丰富的地下水,使其具备地热资源形成的地质构造和水文条件。基于塔什库尔干盆地北部的曲曼地区地质构造、湖相地层年代学调查研究,该地区发育晚更新世的NNE向f_1和f_2正断层以及第四纪沉积物之下存在隐伏的近EW向的断层f_3。这3条断层是塔什库尔干断裂在不同构造演化时期形成的次级断层。结合EH-4电磁成像和钻孔及抽水试验等资料表明NNE向f_1和f_2正断层是地热系统的导水通道,而近EW向f_3断层为导热通道。该地区地热模式是大地热流为热源-地下水深循环逐渐加热-构造控水和控热。  相似文献   

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