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1.
Guojiang Liu 《Geophysical Prospecting》1994,42(4):277-302
The Bjøirnøya West Basin lies between latitudes 73° and 74°, longitudes 16°E and 18°E, contains at least 8 km of sediments deposited from the Late Jurassic, and is of considerable interest for hydrocarbon exploration. The Cenozoic extensional tectonics in the basin can be clearly seen from seismic data with normal faulting and from subsidence curves with rapid subsidence. The extension occurred during the Late Palaeocene with active extension lasting about 6 million years (m.y.) followed by thermal cooling. The tectonic subsidence within the study area shows a three-phase development: phase 1, synrift (58–52 Ma (million years before the present day)), is characterized by rapid subsidence; phase 2, postrift (52–5 Ma), by slow subsidence with occasional uplift; and phase 3 (5–0 Ma), by rapid subsidence. An adaptive finite-element model, with consideration of the radiogenic heat production in the lithosphere, has been used to model the subsidence and heat flow. The modelling of subsidence shows the β-factor distribution varying from 1.9 to 3.5 with an average of 2.4 for the uniform lithospheric extension. The heat-flow modelling predicts a rapid increase of heat flow during the Early Palaeocene. The maximum heat flow at about 52 Ma, which could be as much as 3.0 hfu (10?6 cal/cm2/s), was followed by a decrease in heat flow. A plate-weakening model has been proposed to explain the rapid subsidence for the last 5 m.y. by flexure of the elastic lithosphere which is weakened by a decrease in elastic thickness caused by an increase of the temperature gradient in the lithosphere. The plate-weakening model predicts a heat-flow increase at 5 Ma of up to 2.0 hfu. Our study, using quantitative modelling of the tectonic subsidence, provides a partial (if not a full) understanding of the tectonic development and thermal evolution of the Bjønøya West Basin. 相似文献
2.
Sedimentary basin formation with finite extension rates 总被引：4，自引：0，他引：4
Thinning of continental crust by rapid stretching of the lithosphere produces an initial subsidence and thermal anomaly. When stretching ceases, slow decay of the thermal anomaly produces subsidence (due to thermal contraction) on a time scale of approximately 60 Ma. The dependence of the heat flow and subsidence histories on the rate of extension is determined here using a time-dependent analytical model. Results are compared with the predictions of a simpler instantaneous stretching model and constraints on the use of the latter are provided in terms of the duration and amount of stretching. For most basins the simple model gives reasonably accurate results provided the duration of stretching is less than 20 Ma. 相似文献
3.
南海北部洋陆转换带是近年来基础科学研究和深水油气勘探热点地区.本文在详细研究南海北部洋陆转换带新采集的二维长电缆深反射地震剖面资料的基础上,采用挠曲悬臂梁模型和挠曲回剥模型算法,分别计算了上地壳、地壳和整个岩石圈拉伸系数,实验结果表明,研究区洋陆转换带盆地岩石圈发生了与深度相关的拉伸变形过程,并且随深度增加,拉伸量逐渐变大,该结果解释了南海北部盆地裂后阶段发生的加速沉降现象.同时,本文结合南海北部洋陆转换带盆地发育过程的特点,将洋陆转换带盆地演化划分为陆内裂陷阶段、裂后热沉降阶段和裂后加速沉降阶段.本研究将有助于认识南海北部深水盆地特征,并对大陆边缘动力学研究和陆缘盆地深水区油气勘探有重要意义. 相似文献
4.
Heterogeneous stretching, simple shear and basin development 总被引：1，自引：0，他引：1
M.P. Coward 《Earth and Planetary Science Letters》1986,80(3-4):325-336
The models of basin development which involve either homogeneous stretching of the whole lithosphere or displacement on a lithospheric-scale shear zone, are but two end members of a range of possible extensional models. The homogeneous extension model thins the lower lithosphere beneath the thinned upper crust and superimposes a thermal subsidence basin on the earlier fault bounded basin. The shear zone model offsets the zone of lower lithospheric stretching and thermal subsidence. It is more likely that the zones of upper and lower lithospheric stretching will be heterogeneous and patchy, but will often overlap in plan view. This will produce localised uplift and subsequent thermal subsidence within the faulted basin and may explain many of the anomalies between the various stretching estimates made using different structural, stratigraphic and geophysical techniques. The model which combines heterogeneous lithospheric stretching and associated simple shear may explain: (1) variations in dip of the major detachment zones in the large basins, (2) variations in types of strain on or beneath the detachment zones, (3) regional uplift of part of a basin, to erode the earlier fault blocks, and (4) the development of volcanism in basins with only low values of upper crustal extension. The zone of stretched lower crust and lithospheric mantle may lie beneath the centre of the zone of upper crustal stretching, or to one side. It may be linked to the upper crustal zone by faults which dip consistently in one direction, or by extensional systems which change their dominant dip direction with depth, pulling out the mid-crust as one or more wedges. Possible examples are discussed from the Basin and Range province and northwest European continental shelf. 相似文献
5.
本文在等黏态角落流模型的基础上,建立了上升离散地幔流场,将该流场作用于大陆岩石圈底部,能解释岩石圈减薄、裂解并最终形成海底扩张和张裂大陆边缘等一系列过程.数值模拟的结果表明,岩石圈在上升离散地幔流的作用下发生依赖于深度的伸展减薄,表现为不同深度的拉张因子不同,地表热流显著升高,热扰动引起的均衡调整造成地表沉降,同时热扰动造成岩石圈流变强度尤其是在变形中心处显著减小,脆性变形临界深度变浅,而韧性变形范围扩大.在上升离散地幔流的持续作用下最终导致大陆裂解,岩石圈地幔出露,形成海底扩张和张裂大陆边缘. 相似文献
6.
本文利用热导率、热容、热膨胀系数等参数随温度变化的经验表达式,在板块模型的基础上用隐式有限差分方法解非线性热传导方程,并利用北太平洋和北大西洋海底年龄与水深数据反演了大洋岩石圈厚度与底界温度等参数,结果表明大洋岩石圈的厚度在105 km左右,岩石圈底界温度在1450℃左右,这与Stein等用全球大量数据反演的结果一致.将变参数模型用到岩石圈拉张成盆的模拟中,结果表明当考虑岩石圈热参数随温度变化之后,预测的地表热沉降要大于常参数均匀伸展模型的预测量.由此我们指出：McKenzie的均匀伸展模型预测的初始沉降偏大而热沉降偏小,可能与该模型没有考虑热参数随深度(即温度)变化有关. 相似文献
7.
为了考察渤海湾盆地济阳坳陷新生代裂后不整合及加速沉降事件并探讨其成因机制，利用悬臂梁模型和二维挠曲回剥模型的正反演模拟，对济阳坳陷2条NS向剖面新生代的构造演化进行了重建.正演计算表明，要反映14 Ma的盆地结构，需要叠加断陷阶段及裂后不整合时期发生的构造抬升事件，叠加的构造抬升量在坳陷东北部比西南部大；反演计算表明，要恢复到14 Ma的盆地结构，按照断层估算的拉张系数产生的热沉降不足以恢复当时的古水深，如果要通过人为增加构造沉降以恢复到14 Ma的古水深，那么坳陷东北部比西南部需要更大的沉降量.结果说明，济阳坳陷在新生代发育时，除了水平伸展产生的岩石圈被动减薄外，可能还叠加了垂向因素引起的岩石圈主动减薄；14 Ma以来发生的裂后加速沉降有从坳陷东北部向西南部推进的趋势.分析表明除了水平伸展诱发软流圈热扰动及随后快速热衰减外，岩石圈拆层作用、岩石圈地幔交代作用等主动因素，也会产生裂后不整合及加速沉降事件. 相似文献
8.
沉积盆地岩石圈热结构特征是岩石圈构造-热演化过程的综合反映和盆地热史恢复的约束条件,对盆地动力学研究和油气资源评价具有重要意义.由于海洋勘探难度大、勘探程度低,相对于大陆地区,边缘海盆地比较缺乏岩石圈热结构方面的研究.本文在收集整理珠江口盆地及邻区大地热流数据的基础上,补充收录了自2003年以来发表的新数据,绘制了研究区最新版的大地热流等值线图;基于中美合作双船地震剖面揭示的深部地壳结构计算了研究区的壳-幔热流、深部温度以及"热"岩石圈厚度.研究表明,珠江口盆地地壳热流介于18.7~28.6 mW·m-2,地幔热流介于36.9~91.4 mW·m-2,壳幔热流比值0.23~0.75;由陆架、陆坡至中央海盆,在地壳热流逐渐减小的情况下地表热流逐渐递增,说明地表热流分布主要受深部热作用控制;盆地"热"岩石圈厚度介于34.0~87.2 km,平均65.5 km,反映出显著拉张减薄的特征. 相似文献
9.
Formation of deep basins in continental crust is usually explained by stretching. Intense stretching produces typical deformations in sedimentary cover. These deformations are observed in rift valleys. Deformations produced by stretching can in principle be revealed in presentsedimentary basins. There are also simple ways to reveal such deformations in fold belts, where the remmants of numerous deep basins in the continental crust were found. The sedimentary cover structure was analyzed in the Urals, Appalachians, Scandinavian Caledonides, North-American Cordilleras and in the Alpine, Verkhoyansk and Franklinian fold belts, but no deformations that are typical for significant stretching of continental lithosphere have been found there in most of the deep basins in the continental crust. These basins were commonly formed in cool cratonic areas by very rapid subsidence of the duration of a few million years. Such subsidence cannot be explained by thermal relaxation. Thrust loading as a cause of subsidence can also be excluded in most cases. The authors suggest a gabbro to eclogite transformation with the destruction of the basaltic layer as a possible cause of rapid subsidence. This occurs under upwelling of wet asthenosphere of not too high temperature to the base of the crust. Crustal attenuation from destruction of the basaltic layer permits an intense subsequent crustal shortening. This may explain why continental crust was intensely compressed only in those regions, where rapid subsidence of large magnitude took place. 相似文献
10.
Yu. I. Galushkin G. L. Leitchenkov Yu. B. Guseva E. P. Dubinin 《Izvestiya Physics of the Solid Earth》2018,54(1):79-90
The burial history and thermal evolution of the lithosphere within the passive nonvolcanic Antarctic margin in the region of the Mawson Sea are numerically reconstructed for the margin areas along the seismic profile 5909 with the use of the GALO basin modeling system. The amplitudes of the lithosphere stretching at the different stages of continental rifting which took place from 160 to 90 Ma ago are calculated from the geophysical estimates of the thickness of the consolidated crust and the tectonic analysis of the variations in the thickness of the sedimentary cover and sea depths during the evolution of the basin. It is hypothesized that the formation of the recent sedimentary section sequence in the studied region of the Antarctic margin began ~140 Ma ago on a basement that was thinned by a factor of 1.6 to 4.5 during the first episode of margin stretching (160–140 Ma) under a fairly high heat flux. The reconstruction of the thermal regime of the lithosphere has shown that the mantle rocks could occur within the temperature interval of serpentinization and simultaneously within the time interval of lithospheric stretching (–160 < t <–90 Ma) only within separate segments of profile 5909 in the Mawson Sea. The calculations of the rock strength distribution with depth by the example of the section of pseudowell 4 have shown that a significant part of the crust and uppermost mantle fall here in the region of brittle deformations in the most recent period of lithosphere stretching (–104 to–90 Ma ago). The younger basin segments of profile 5909 in the region of pseudowells 5 and 6 are characterized by a high heat flux, and the formation of through-thickness brittle fractures in these zones is less probable. However, serpentinization could take place in these areas as in the other margin segments at the stage of presedimentation ultra slow basement stretching. 相似文献
11.
渤海盆地大地热流测量和利用磷灰石裂变径迹及镜质体反射率数据进行的盆地热史恢复结果表明：盆地现今热流值为５０-７５ｍＷ／ｍ２,背景热流值达６３．６ｍＷ／ｍ２,而早第三纪砂河街组和东营组沉积时（２５-５０Ｍａ）盆地古热流值为７０-９０ｍＷ／ｍ２．盆地构造沉降史分析显示,盆地（含辽东湾地区和渤海地区）经历了早期的裂谷阶段（２５一扣Ｍａ）和后期的热沉降阶段（２５-０Ｍａ）,其中早期的裂谷阶段包含了两个裂谷亚旋回．渤海盆地内的后期热沉降叠加了１２Ｍａ以来由高密度地幔及岩石圈冷却诱发的快速均衡沉降．渤海盆地现今较低的大地热流值和较高的古热流及典型的裂谷型构造沉降样式等支持了渤海盆地板内裂谷盆地的大地构造属性并为渤海盆地构造一热演化提供了重要认识． 相似文献
12.
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14.
The GALO basin modeling system has been applied for the numerical reconstruction of the subsidence history, variations in temperature, and maturity of the organic matter of sedimentary rocks composing the main tectonic structures of Sirte Basin. The reconstruction was carried out for eight sedimentary cross sections along the profile stretching from the Cyrenaica Platform on the eastern coast of the basin to the Hun Graben on its western wall. The interval of depths for temperature calculations included the sedimentary layer, consolidated crust, and the mantle to below 100 km. This extensive depth coverage made it possible to use the analysis of the variations in the tectonic subsidence of the basin for estimating the amplitudes and duration of the events of thermal activation and extension of the lithosphere of the basin in the history of its evolution. The modeling suggests that thermal activations of the lithosphere in the Albian-Cenomanian and Oligocene-Pleistocene are common for all tectonic structures of the Sirte Basin and the Cyrenaica Platform and that a relatively high temperature regime is also characteristic of the present-day conditions in the Sirte Basin and Cyrenaica Platform. To a considerable extent, such a regime is caused by the thermal activation of the lithosphere of the basin during the last 10 Ma. The intensity of this activation is highest in the western part of the basin, where it is accompanied by the highest erosion amplitudes. The analysis of the variations in tectonic subsidence of the basement also suggests a series of intervals of lithospheric extension, which accounts for the stages of relatively rapid subsidence of the basin. Two intervals of significant extension of the lithosphere in the Upper Cretaceous and Paleocene are common for all areas within the basin. Here, the total amplitudes of the crustal extension attained 1.5 in the central part of the Sirte Basin (the Ajdabiya and Maradah troughs and Zelten and Dahra platforms), was equal to 1.3 in the Hameimat and Zallah troughs, and were minimal (1.11–1.17) in the periphery of the basin (within the Hun Graben and Cyrenaica Platform). 相似文献
15.
The time history and magnitude of the subsidence in a sedimentary basin depends on the extent to which the lithosphere is thinned by stretching and on its original thickness. Hence the history and stratigraphic thickness of early Precambrian sedimentary basins, preserved as greenstone belts, should provide estimates of lithospheric thickness during the first half of the earth's history. Only the thickness of shallow-water sediments deposited without faulting is of relevance, and the best available estimates are compatible with all lithospheric thicknesses which have been suggested. The same is true of the estimates of the duration of the subsidence. Nonetheless radiometric dating can probably now provide estimates of the duration of the subsidence which are sufficiently accurate to constrain the models of the earth's thermal history if carried out for this purpose. 相似文献
16.
岩石圈热结构是盆地现今地温场研究的重要延伸和扩展,是了解大陆岩石圈构造变形及演化等大陆动力学问题的重要窗口,更是地热田热源机理研究的核心问题.本次工作,在系统分析渭河盆地现今地温场和水动力系统基础上,编制了渭河盆地大地热流分布等值线图;通过实测生热率等热物性参数,利用一维稳态热传导方程计算了研究区岩石圈热结构,并分析了渭河盆地岩石圈热结构特征和地热田热源机理.结果表明,渭河盆地现今大地热流值分布范围为62.5~80.2mW·m-2,平均为70.8±4.8mW·m-2,西部明显高于东部,西安坳陷最高,咸礼凸起次之;渭河断裂并不是控热断裂,其沟通作用引起的水热循环一定程度上影响了浅部热量再分配,对渭河盆地地温场并没有起到明显的控制作用.西安坳陷—咸礼凸起地壳热流介于32.2~37.5mW·m-2之间,平均为34.6mW·m-2;地幔热流分布范围为33.8~38.9mW·m-2,平均为36.0mW·m-2;地壳热流和地幔热流的总体变化趋势一致,西安坳陷高于咸礼凸起,分析认为西安坳陷沉积层厚度大于后者,且沉积层放射性生热率更大,是造成西安坳陷地壳热流高于咸礼凸起的原因,而西安坳陷相比咸礼凸起更高的地幔热流,表明西安坳陷深部活动性强于咸礼凸起.西安坳陷和咸礼凸起地壳/地幔热流比值相近,介于0.93~1.01之间,平均为0.96,"热"岩石圈厚度约为95~101km.渭河盆地岩石圈热结构特征与鄂尔多斯盆地在很大程度上具有相似性,暗示着二者具备相似的深部稳定性,这与渤海湾盆地为代表的中国东部中—新生代主动裂谷盆地岩石圈热结构特征截然不同,表明渭河盆地为被动伸展裂陷.从鄂尔多斯盆地、渭河盆地、山西裂谷到华北盆地,"热"岩石圈厚度的有序变化表明太平洋板块俯冲引起的地幔对流对华北地块深部动力学行为的影响主要发生在太行山以东,而太行山以西的鄂尔多斯盆地和渭河盆地则影响甚微,这种空间差异影响从侧面暗示着华北克拉通破坏过程的有序性.综合分析渭河盆地地质—地球物理资料认为,岩石圈表层伸展破裂、深部重力均衡调整进而引起软流圈被动上涌,其产生的相对高地幔热流的热传导和深大断裂沟通的水体热对流相互叠加作用,共同构成了渭河盆地中—低温地热田的热源机理. 相似文献
17.
V. O. Mikhailov T. Parsons R. W. Simpson E. P. Timoshkina C. Williams 《Izvestiya Physics of the Solid Earth》2007,43(1):75-90
Data on present-day heat flow, subsidence history, and paleotemperature for the Sacramento Delta region, California, have
been employed to constrain a numerical model of tectonic subsidence and thermal evolution of forearc basins. The model assumes
an oceanic basement with an initial thermal profile dependent on its age subjected to refrigeration caused by a subducting
slab. Subsidence in the Sacramento Delta region appears to be close to that expected for a forearc basin underlain by normal
oceanic lithosphere of age 150 Ma, demonstrating that effects from both the initial thermal profile and the subduction process
are necessary and sufficient. Subsidence at the eastern and northern borders of the Sacramento Valley is considerably less,
approximating subsidence expected from the dynamics of the subduction zone alone. These results, together with other geophysical
data, show that Sacramento Delta lithosphere, being thinner and having undergone deeper subsidence, must differ from lithosphere
of the transitional type under other parts of the Sacramento Valley. Thermal modeling allows evaluation of the rheological
properties of the lithosphere. Strength diagrams based on our thermal model show that, even under relatively slow deformation
(10−17 s−1), the upper part of the delta crystalline crust (down to 20–22 km) can fail in brittle fashion, which is in agreement with
deeper earthquake occurrence. Hypocentral depths of earthquakes under the Sacramento Delta region extend to nearly 20 km,
whereas, in the Coast Ranges to the west, depths are typically less than 12–15 km. The greater width of the seismogenic zone
in this area raises the possibility that, for fault segments of comparable length, earthquakes of somewhat greater magnitude
might occur than in the Coast Ranges to the west.
The text was submitted by the authors in English. 相似文献
18.
渤海湾盆地是华北最大的新生代裂谷盆地,具有最完整的新生代地层记录,是研究盆地演化的理想区域.本文基于二维多期拉张模型,对渤海湾盆地内9条地震解释剖面进行新生代构造-热演化模拟,以揭示盆地拉张强度及热演化的时空差异性,为探讨盆地演化的地球动力学机制提供依据.研究结果表明:渤海湾盆地各坳陷新生代期间的总拉张系数为1.28～2.39,渤中坳陷和辽东湾坳陷的总拉张系数最大,而辽河坳陷和临清坳陷的拉张系数最小.盆地基底热流在古近纪中、晚期达到峰值71～100mW·m-2,之后逐渐降低至现今.盆地西部热流峰期出现的时间早于东部.由盆地拉张系数和基底热流的研究结果得出,渤海湾盆地新生代的拉张有着自西向东,自南向北的迁移,与沉积、沉降中心的迁移方向一致.太平洋板片新生代期间的幕式向东后撤可能是造成渤海湾盆地幕式拉张及拉张中心向东迁移的主要动力学机制. 相似文献
19.
本文以多孔介质中大尺度传热问题为基础,结合热平衡理论分析与数值计算,探讨了上通流对大陆岩石圈地幔-地壳热结构模式的潜在影响.根据大陆岩石圈中孔隙波传热概念模型的初步理论分析结果,指出了采用理论分析和数值模拟相结合的方法在研究大陆岩石圈地幔-地壳热结构模式时的重要性.理论分析方法可用来确定岩石圈尺度范围内大陆岩石圈的厚度和大陆地壳相关的边界条件,从而为地壳范围内数值模型的建立提供一些重要信息.数值模拟方法可以用来模拟地壳尺度范围内地壳的详细结构和复杂几何形状.如果地壳内的热分布是所考虑的主要因素,采用具有地壳尺度的合理数值模型可以有效减少计算机工作量.利用理论分析方法求出的岩石圈尺度范围内大陆岩石圈厚度与地幔传导热流之间关系的理论解,不仅可以用来验证模拟大陆岩石圈内传热问题所采用的数值方法, 而且可以用来初步研究大陆岩石圈内热分布的基本规律,为研究岩石圈地幔热事件中大陆岩石圈热减薄过程提供相应的边界条件.本文从理论分析的观点初步探讨了中国大陆不同构造背景下大陆岩石圈的热结构模式,其结果与从地球物理和地质资料中获得的大陆岩石圈热结构模式十分吻合.研究结果表明由大陆岩石圈中孔隙波传播所导致的上通流是影响大陆岩石圈地幔-地壳热结构模式及大陆岩石圈地幔与地壳之间物质和能量交换的可能机制之一. 相似文献
20.
Thermally, the lithosphere may be defined as that outer portion of the earth in which heat is transferred primarily by conduction. It generally includes the crust and part of the mantle. The thermal regime of continental lithosphere is determined by many factors including heat flow from the asthenosphere, the vertical and lateral variation of both thermal conductivity and radiogenic heat production, tectonic history, and such superficial processes as climatic history and the shallow hydrothermal regime. From studies of the global heat flow data set, two generalizations regarding continental lithosphere have arisen, namely that: 1) there is a negative correlation between heat flow and tectonic age of continental lithosphere; and 2) the thermal evolution of continental lithosphere is similar to that of ocean basins with the result that the “stable geotherm” is similar in both environments. When continental heat-flow data are studied from a regional rather than a global point of view, considerable doubt arises as to the general applicability of either statement. R. U. M. Rao and his associates have demonstrated that while Precambrian terranes do have demonstrably lower heat flows than, say, Tertiary terranes, the data are not normally distributed and it is not possible to establish a negative correlation between heat flow and age in any rigorous statistical way. The scatter in the relation may be explained in terms of the variations in the duration, intensity and even the sign of continental thermotectonic events in contrast to the simple situation (creation of new oceanic lithosphere at mid-ocean ridges) which prevails in the oceans. The scatter also is partially attributable to the large and laterally variable radiogenic component of heat flow on continents. For a province for which a heat flow-heat production relation has been established, much of the scatter in surface heat flow due to crustal radiogenic heat production versus age is eliminated by determining reduced heat flow (surface heat flow minus radiogenic component) as a function of tectonic age, but much scatter remains, and it is still not possible to establish a heat flux-age relation in a rigorous way. Primarily because of the spatial variability in radiogenic heat production, no single geotherm can be used to characterize the thermal regime of a stable continental terrane. Thus, while some sites on stable continental blocks may have a geotherm fortuitously similar to that for old ocean basins, there is no reason to expect that this will be true generally, and many stable continental terranes will be characterized by geotherms markedly different from the geotherm for old ocean basins. 相似文献