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1.
Thermal-rheological structure of lithosphere beneath the northern flank of Tarim Basin, western China: Implications for geodynamics 总被引：2，自引：3，他引：2
LIU Shaowen WANG Liangshu LI Cheng LI Hua HAN Yongbing JIA Chengzao & WEI Guoqi .Department of Earth Sciences Nanjing University Nanjing China .Chinese Petroleum Exploration Development Institution Beijing China 《中国科学D辑(英文版)》2004,47(7):659-672
Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514℃ to 603℃ and the thermal lithosphere where the heat conduction dominates is 138-182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however,the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers,which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northem flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest.The total lithospheric strength of this region is 4.77× 1012-5.03 × 1013 N/m under extension, and 6.5 × 1012-9.4× 1013 N/m under compression. The lithospheric brittle-ductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the Tarim lithosphere makes it little deform interior, but only into flexure under the sedimentation and tectonic loading associated with the rapid uplift of the Tianshan at its northern margin during the Indian-Eurasian continental collision following the Late Eocene. Finally, the influences of factors, such as heat flow, temperature,crustal thickness, and especially basin sediment thickness, on the lithospheric strength are discussed here. 相似文献
2.
Geodynamic characteristics of tectonic extension in the northern margin of South China Sea 总被引：1，自引：0，他引：1
Based on the geothermal and gravitation methods, this paper investigated the rheological and thermal structure of the lithosphere
under the northern margin of South China Sea. The result shows that the temperature of the upper crust is 150–300°C lower
than that of the lower crust, and the viscous coefficient of the upper crust is 2–3 orders of magnitude larger than that of
the lower crust. It reveals that the upper crust is characterized by brittle deformation while the lower crust by ductile
deformation. A channel of lower-viscosity should be formed between the upper and lower crust when the lithosphere is scattered
and spreads out toward ocean from northwest to southeast along the northern margin of South China Sea. And, a brittle deformation
takes place in the upper part of the lithosphere while a ductile deformation takes place in the lower part of the lithosphere
due to different viscous coefficients and temperature. The layered deformation leads the faulted blocks to rotate along the
faulting and the marginal grabens to appear in the northern margin of South China Sea in Cenozoic tectonic expansion. 相似文献
3.
依据地震波速得到的上地幔温度和气象台站记录的地表温度为约束,结合地表热流和热导率观测数据,利用有限元方法计算了中国大陆及邻区岩石圈三维热结构.基于此温度结果和GPS观测得到的应变率数据,以滑动摩擦、脆性破裂和蠕变三种强度机制为约束,计算得到了中国大陆及邻区岩石圈三维流变结构.结果显示:弱强度和低等效黏滞性系数的下地壳在中国大陆及邻区普遍存在,并且下地壳的流变强度和等效黏滞性系数比上地壳和岩石圈地幔一般要低1~2个数量级;中国大陆范围内青藏高原存在着厚度最大、强度最低的下地壳;青藏高原的岩石圈强度和等效黏滞性系数比华北、华南和印度板块的都要低;岩石圈流变结构的横向分布特征与重力梯度带和地形过渡带比较一致. 相似文献
4.
Brittle deformation of oceanic lithosphere due to thermal stress is explored with a numerical model, with an emphasis on the spacing of fracture zones. Brittle deformation is represented by localized plastic strain within a material having an elasto-visco-plastic rheology with strain softening. We show that crustal thickness, creep strength, and the rule governing plastic flow control the formation of cracks. The spacing of primary crack decreases with crustal thickness as long as it is smaller than a threshold value. Creep strength shifts the threshold such that crust with strong creep strength develops primary cracks regardless of crustal thicknesses, while only a thin crust can have primary cracks if its creep strength is low. For a thin crust, the spacing of primary cracks is inversely proportional to the creep strength, suggesting that creep strength might independently contribute to the degree of brittle deformation. Through finite versus zero dilatation in plastic strain, associated and non-associated flow rule results in nearly vertical and V-shaped cracks, respectively. Changes in the tectonic environment of a ridge system can be reflected in variation in crustal thickness, and thus related to brittle deformation. The fracture zone-free Reykjanes ridge is known to have a uniformly thick crust. The Australian-Antarctic Discordance has multiple fracture zones and thin crust. These syntheses are consistent with enhanced brittle deformation of oceanic lithosphere when the crust is thin and vice versa. 相似文献
5.
通过地质、地球物理和地球化学资料分析,建立了东秦岭地学断面带地壳二维深度-强度剖面,揭示了该造山带的地壳结构和流变学分层性．脆性的上地壳南薄北厚;中、下地壳包括莫霍面呈现水平流变状态,南端蠕变特征更明显;上地幔流变强度较大其地壳类型是栾川以南为H型地壳,构成中、新生代造山带的核部,具有伸展构造和走滑构造的特征,栾川以北为C型地壳,中、新生代的大陆汇聚带．东秦岭地学断面带整体上看为C-H型地壳,反映了后造山期陆内造山的构造特征．地壳物质为长英质-石英闪长质壳内软层具有低速、高热、强网状反射和低强度蠕变的地球物理特征,是后造山期经过调整的水平流变层. 相似文献
6.
The experimental studies done at high temperature and high pressure find that increased temperature can lead to dramatic velocity and strength reductions of most of rocks at high confining pressure[1,2]. What causes this phenomenon? Is it due to dehydrati… 相似文献
7.
研究了温度和应变率对岩石破裂强度的影响,得到了岩石圈中一些典型岩石破裂强度的新的经验规律.新的经验规律除考虑围压和标本尺度的影响外,还考虑了温度和应变率的影响,并增加了新岩石的结果,所以更能反映岩石圈内岩石破裂的真实状态.通过对鄂尔多斯平均流变结构的计算和对比研究表明：传统的忽略脆性破裂的流变模型过高地估计了流变强度,流变机制的分布也不尽合理.而考虑了脆性破裂机制的流变模型的结果表明脆性区分为两部分,浅部以摩擦滑动机制控制,深部以脆性破裂机制控制.由于新的经验规律考虑的代表性岩石更全面,并考虑了应变率的影响,得到的脆性区的范围进一步增大,流变强度进一步降低. 相似文献
8.
三维黏弹性数值模拟华北盆地地震空间分布与构造应力积累关系 总被引：2，自引：1，他引：1
华北盆地为我国板内地震多发区域,历史以来相继发生多次破坏性大地震.前人地震勘探与震源定位结果揭示了华北地震的空间分布特征:横向上,华北地震基本发生在地壳的薄弱地带(Moho面上隆),或者地壳厚度的急剧变化带;纵向上,华北地震在地壳一定深度范围内呈现成层分布特征;主震一般在上地壳底部9~15 km深度范围,余震多发生在大约深5~25 km的上地壳与中地壳范围内,在中地壳下层与下地壳中仅有少量或者鲜见有余震发生.为研究解释华北盆地地震空间分布的以上特征,本文建立了华北盆地岩石圈三维黏弹性有限元模型.震源机制和GPS反映华北盆地处于NNE最大主压应力方向挤压,因此对模型边界施以恒定的位移速率边界条件;数值模拟华北岩石圈各层位在数百年以上长期匀速构造挤压作用下的应力积累特征,分析了华北地震空间分布与构造应力积累速率的关系,探讨了地壳结构与地壳分层流变性质对地壳应力积累的影响.计算结果表明,Moho面的隆起与地壳各层位岩石介质的黏滞系数是华北盆地地震孕育的重要因素.华北盆地在构造挤压的持续作用下,Moho面隆起处产生明显应力集中现象.该区域应力在长时期的积累过程中,在脆性的上地壳与中地壳上层,应力表现近于线性增长趋势,上地壳底部较其它深度有最大的应力增长率,其主震可以在应力积累至岩石破裂强度时发生;在脆、韧性转换的中地壳下层,应力增长速率次之,华北地震的大部分余震可能在该层位为主震所触发;而在柔性的下地壳应力增长近于指数形式,稳定状态之后其应力增长速率近于零,而鲜有地震发生.地壳各层位的应力增长率差异与地震成层分布的现象揭示了华北地壳的分层流变性质:脆性(上地壳)-较弱脆性(中地壳上层)-较弱韧性(中地壳下层)-较强韧性(下地壳)-韧性(岩石圈上地幔)的分层流变结构. 相似文献
9.
Peak lithospheric strength should reside in the rocks that, under the applied stress, cannot either creep (due to low temperature) or break (due to high confining pressure). The greatest resistance comes from dry olivine/pyroxene-rich upper mantle/lowermost crust at Moho conditions (400–600 °C and > 1 GPa). We have conducted laboratory experiments to investigate the importance of the unbreakable core of the lithosphere in between its brittle and ductile parts and conclude that it can control the large-scale lithospheric deformation pattern under shortening. Regardless of the thickness of the unbreakable core, it acts as a restraining layer that is easily flexed but is unstretchable. This eliminates large scale brittle faulting or homogeneous thickening as available shortening modes and results in irregular wrinkling of the unbreakable layer. We discuss geodynamic implications of our laboratory experiments and advocate studies of large scale buckling of the lithosphere as a relevant shortening mode. 相似文献
10.
LIU Shaowen WANG Liangshu GONG Yuling LI Cheng LI Hua & HAN Yongbing . Department of Urban Resources Nanjing University Nanjing China . Department of Earth Sciences Nanjing University Nanjing China 《中国科学D辑(英文版)》2005,48(10)
Thermal regime of the lithosphere is the scenario of the lithospheric thermal evolution, and the thermo-mechanical state of lithosphere definitively controls its deformation style and mechanism. Better understanding of the lithospheric deep thermal-rheo- logical structure of sedimentary basin will shed light on the formation and evolution dynamic process of the basin. Surface tectonics is the response of the deep structure, and is controlled by the lithospheric ther-mal-rheological properties.… 相似文献
11.
Control of paths of quaternary volcanic products in western Bohemian Massif by rejuvenated Variscan triple junction of ancient microplates 总被引：1，自引：1，他引：0
Our objective is to look for deep paths of Cenozoic volcanism and migration routes of active mantle volatiles through the
lithosphere of the western Bohemian Massif. We show that the rejuvenated junction of three mantle domains, delimited by different
orientation of seismic anisotropy and belonging to originally separated microplates — the Saxothuringian (ST), Moldanubian
(MD) and Teplá-Barrandian (TB) — can provide the easiest upward routes of fluids through the deep lithosphere. Geographic
distribution of mantle-fluid escapes at the surface suggests fluid migration through the ductile lower crust and through partly
open faults in the rigid upper crust, which is locally detached and shifted from its lower part and from the mantle lithosphere.
Present-day escapes of mantle-derived helium and CO2 concentrate mainly in two tectonically different crust edifices — in the Cheb Basin (CHB) and in an allochtonous block called
the Mariánské Lázně Complex (MLC). Crystalline basement of the CHB developed above the Variscan ‘triple junction’ of the mantle
lithosphere domains. The basement was extended during the Cenozoic and dissected by systems of faults into small partly sunken
blocks. Thanks to buoyancy the mantle fluids migrate upwards along the lithosphere junction into the faulted basement of the
CHB. The highest CO2 flow and the highest 3He/4He ratios are observed at intersections of major normal faults and along the southern boundary of the Smrčiny (Fichtelgebirge)
granite Pluton. The fluid escapes are separated from the earthquake swarm epicentres. Routes of the fluids to the MLC are
longer and more complicated. Surface escapes tap the mantle fluids mainly from the Mariánské Lázně Fault (MLF) and from the
tectonic boundaries along which the MLC block of the TB lower crust was thrust over the ST complexes. Hypocentres of earthquake
swarms of the two major focal areas at Novy Kostel and Lazy, located mainly at depths of 6–13 km, reside either in granite
or in underlying gneiss, while the escapes of mantle fluids follow major faults or boundaries of crystalline units outside
the Smrčiny and Karlovy Vary granite Plutons. We suggest that primarily those parts of faults in the upper crust, which is
strengthened by granite magmatism and rigid enough to selectively accumulate stresses, are seismoactive. On the other hand,
other parts of the faults tapping ascending mantle volatiles are ‘lubricated’ by the fluids and secondary mineralogical changes,
and thus they cannot accumulate sufficient stresses to be released by earthquakes. A comparison of the most probable paths
of the mantle fluids with the space-time distribution of the Novy Kostel hypocentres does not seem to support the model of
the earthquake swarms triggered by pressurized fluids of mantle origin. 相似文献
12.
自20世纪60年代以来,大陆岩石圈流变学取得了较大的进展,理论和应用研究不断深入.理论上,人们不仅认识到在构造运动中岩石圈介质是流变体而非简单的刚体性和弹性体;并利用矿物和岩石的实验结果提出了岩石圈流变分层的概念,建立了一维流变模型;进而用流变的观点解释了一些具体构造现象,而且开始了三维流变结构的研究,提出了岩石圈流变结构的横向分块纵向分层的观点.应用上,人们已从把流变强度曲线简单地运用于运动学或动力学模型的阶段,进入了在三维空间中定量研究地球动力学问题的阶段.随着岩石圈流变学研究的深入及大陆岩石圈的复杂性,新的问题也不断涌现. 相似文献
13.
岩石流变参数和变形机制是根据断层摩擦和岩石幂次流动本构关系建立岩石圈强度剖面的基础。近 30年来 ,高温高压实验取得了很大进展 ,获得了大量地壳矿物和岩石流变资料。本文系统总结了这些流变实验资料 ,并应用流变数据结合地震震源深度分布 ,对华北地壳流变性质进行了研究。结果表明 ,以花岗岩和低级变质岩为代表的上地壳为脆性破裂 ,其强度受断层摩擦约束 ,以长英质片麻岩为主的中地壳和以中性麻粒岩为主的下地壳上层处于塑性流变状态 ,由干的基性麻粒岩组成的下地壳下层处于脆性向塑性流变的过渡状态。华北地壳的这种物质组成和流变为地壳不同层次的解耦和强震孕育提供了力学条件 ,也构成了不同尺度块体的底边界 相似文献
14.
本文利用瑞利波群速度频散资料和层析成像方法,研究了中国西部及邻近区域(20°N—55°N,65°E—110°E)的岩石圈S波速度结构.结果表明这一地区存在三个以低速地壳/上地幔为特征的构造活动区域:西蒙古高原—贝加尔地区,青藏高原,印支地区.西蒙古高原岩石圈厚度约为80 km,上地幔低速层向下延伸至300 km深度,说明存在源自地幔深部的热流活动.缅甸弧后的上地幔低速层下至200 km深度,显然与印度板块向东俯冲引起俯冲板片上方的热/化学活动有关.青藏高原地壳厚达70 km,边缘地区厚度也在50 km以上并且具有很大的水平变化梯度,与高原平顶陡边的地形特征一致.中下地壳的平均S波速度明显低于正常大陆地壳,在中地壳20~40 km深度范围广泛存在速度逆转的低速层,这一低速层的展布范围与高原的范围相符.这些特征说明青藏高原中下地壳的变形是在印度板块的北向挤压下发生塑性增厚和侧向流动.地幔的速度结构呈现与地壳显著不同的特点.在高原主体和川滇西部地区上地幔顶部存在较大范围的低速,低速区范围随深度迅速减小;100 km以下滇西低速消失,150 km以下基本完全消失.青藏高原上地幔速度结构沿东西方向表现出显著的分段变化.在大约84°E以西的喀喇昆仑—帕米尔—兴都库什地区,印度板块的北向和亚洲板块的南向俯冲造成上地幔显著高速;84°E—94°E之间上地幔顶部速度较低,在大约150~220 km深度范围存在高速板片,有可能是俯冲的印度岩石圈,其前缘到达昆仑—巴颜喀拉之下;在喜马拉雅东构造结以北区域,存在显著的上地幔高速区,可能阻碍上地幔物质的东向运动.川滇西部岩石圈底界深度与扬子克拉通相似,约为180 km,但上地幔顶部速度较低.这些现象表明青藏高原岩石圈地幔的变形/运动方式可能与地壳有本质的区别. 相似文献
15.
A three-dimensional model for the central Fennoscandian Shield was constructed for analysing the thermal, the rheological and the structural conditions in the lithosphere. The mesh covers a rectangular area in the southern Finland with horizontal dimensions of 500 km × 400 km and a depth extent of 100 km. Structural boundaries are derived from the several deep seismic soundings carried out in the area. Constructed model is first used in the calculation of the thermal and the rheological models and secondly in analysing the stress and the deformational conditions with the obtained rheology. Thermal and structural models are solved with the finite element method. The calculated surface HFD is between 40 and 48 mW m−2 in the Proterozoic southern part and below 40 mW m−2 in the older and northern Archaean part of the model. The calculated rheological strength shows a layered structure with two individual rheologically weak layers in the crust and strong layer in the upper part of the lower crust. The minimum brittle–ductile transition (BDT) depth is around 10 km in the southern part of the model while in the north and north-eastern parts the BDT depth is around 45–50 km. Comparison with the focal depth data shows that as most of the earthquakes occur no deeper than the depth of 10 km are they located in the brittle regime. Resulting stress conditions and possible regions of deformation after the model is subjected to pressure of 50 MPa reveals that the stress field is quite uniformly distributed in different crustal layers and that the elastic parameters control more the state of the stress than the applied rheological structure. In the upper crust, the stress intensity has values between 42 and 45 MPa whereas in the middle crust the values are around 50 MPa. Comparison of the 3-D model with earlier 2-D models shows that some differences in the results are to be expected. 相似文献
16.
青藏高原东缘低地形变速率的龙门山断裂带上相继发生了2008汶川Mw7.9级地震和2013芦山Mw6.6级地震.地震勘探与震源定位结果揭示了龙门山区域地震空间分布特征：纵向上,龙门山断裂带这两次地震主震均发生在龙门山断裂带上地壳的底部（14~19 km）,绝大部分余震均发生在上地壳范围（5~25 km）,而在其中、下地壳深度范围内鲜见余震发生;横向上,地震（Mw>3）在龙门山断裂带青藏高原一侧密集分布且曾有大震发生,而四川盆地地震稀少（Mw>3）.为探讨龙门山断裂带地震发生机理,并解释以上龙门山区域地震空间分布特征,本文建立了龙门山断裂带西南段跨芦山地震震中区域的四种不同流变结构的龙门山断裂带三维岩石圈模型,以地表GPS观测资料为约束边界条件,数值模拟龙门山断裂带岩石圈在数千年以上长期匀速构造挤压作用下的应力积累特征,探讨了地壳分层流变性质对地壳应力积累的影响,分析了该区域地震空间分布与构造应力积累速率的关系.计算结果表明：该区域在数千年的应力积累过程中,脆性上地壳中应力表现近于恒定值的线性增长趋势,龙门山断裂带上地壳底部出现应力集中积累现象,这一应力集中现象可以解释龙门山断裂带汶川地震与芦山地震主震的发生,及其大部分余震在脆性上地壳中的触发;青藏高原一侧上地壳应力积累速率远远高于四川盆地的应力积累速率,这一应力积累分布现象可以解释龙门山区域青藏高原一侧地震密集而四川盆地地震稀少的地震空间分布特征;通过比较不同流变结构模型中的应力积累状态,认为导致这一应力积累空间分布状态的重要控制因素在于青藏高原中、下地壳较低的黏滞系数与四川盆地中、下地壳较高的黏滞系数的差异.在柔性的中、下地壳内,应力增长近于指数形式,稳定状态之后其应力增长速率近于零,构造应力积累难以达到岩石破裂强度,因而鲜见地震发生.地壳各层位的应力增长率差异与地震成层分布的现象共同揭示了龙门山区域岩石圈分层流变结构：脆性上地壳、韧性中、下地壳（青藏高原一侧较弱,四川盆地一侧较强）、韧性岩石圈上地幔. 相似文献
17.
根据中国地震台网和ISC台站提供的P波走时资料,使用差异演化全局优化算法(DE算法)和移动窗方法反演了琉球-台湾-吕宋地区岩石层尺度的P波速度结构.在台站和地震分布较为密集的地区,反演窗口为2°×2°,移动步长为1°;在台站和地震较少的地区,反演窗口为4°×4°左右,移动步长为2°.反演结果揭示出琉球-台湾-吕宋地区壳幔结构的横向差异:琉球岛弧西侧受冲绳海槽地幔热扰动的地壳减薄,东侧由于菲律宾海板决的俯冲挤压地壳略有增厚;欧亚大陆与菲律宾海板块的相互碰撞导致台湾地区地壳及岩石层明显增厚;吕宋及菲律宾北部岩石层受岛弧火山下方热流影响较大.结果表明,非线性全局优化算法和移动窗方法能够用于反演较大尺度速度结构的横向变化. 相似文献
18.
Seismic tomography of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions 总被引：1，自引：0，他引：1
In the Bohai Bay Basin and its adjacent regions(112°―124°E,34°―42°N),there exists abundant gas-petroleum while modern inter-plate seismic activity is robust.Although the tectonic structure of this region is very complicated,plenty of geological,geophysical and geochemical data and results are obtained through previous researches.On the basis of absorbing previous results,especially various kinds of geological and geophysical results,we collect and process the arrival time of P-wave phases of local events and tele-seismic events recorded by the station within this region from 1978 to 2004,build the responding initial model,and image the velocity structure of the crust and upper mantle of this region via tomography.The perturbation images of various depths and velocity profiles imply that the velocity structure of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions is mainly influenced by the surface tectonic units,and is characterized by "Stripped along east-west,and zoned along south-north";some large-scaled faults penetrate Moho and lithosphere,and provide the channels for the basic lava or hot mass upwelling from the mantle. 相似文献
19.
《Journal of Geodynamics》2007,43(4-5):95-114
A three-dimensional model for the central Fennoscandian Shield was constructed for analysing the thermal, the rheological and the structural conditions in the lithosphere. The mesh covers a rectangular area in the southern Finland with horizontal dimensions of 500 km × 400 km and a depth extent of 100 km. Structural boundaries are derived from the several deep seismic soundings carried out in the area. Constructed model is first used in the calculation of the thermal and the rheological models and secondly in analysing the stress and the deformational conditions with the obtained rheology. Thermal and structural models are solved with the finite element method. The calculated surface HFD is between 40 and 48 mW m−2 in the Proterozoic southern part and below 40 mW m−2 in the older and northern Archaean part of the model. The calculated rheological strength shows a layered structure with two individual rheologically weak layers in the crust and strong layer in the upper part of the lower crust. The minimum brittle–ductile transition (BDT) depth is around 10 km in the southern part of the model while in the north and north-eastern parts the BDT depth is around 45–50 km. Comparison with the focal depth data shows that as most of the earthquakes occur no deeper than the depth of 10 km are they located in the brittle regime. Resulting stress conditions and possible regions of deformation after the model is subjected to pressure of 50 MPa reveals that the stress field is quite uniformly distributed in different crustal layers and that the elastic parameters control more the state of the stress than the applied rheological structure. In the upper crust, the stress intensity has values between 42 and 45 MPa whereas in the middle crust the values are around 50 MPa. Comparison of the 3-D model with earlier 2-D models shows that some differences in the results are to be expected. 相似文献
20.
《Journal of Volcanology and Geothermal Research》1999,91(1):65-78
The tectonic stresses can significantly affect the propagation of a magma-filled crack. It has been pointed out that the rheological boundaries control the emplacement of magmas through the effect of stress. However, it has not been clarified how the role of rheological boundaries depends on the regional tectonic and thermal states. We have evaluated the role of rheological boundaries under various tectonic and thermal conditions and found that the level of magma emplacement may jump according to the changes in the tectonic force or the surface heat flow. The stress profiles were estimated by a simple model of lithospheric deformation. We employed a three-layer model of the lithosphere; the upper crust, the lower crust and the upper mantle have different rheological properties. A constant horizontal force is applied to the lithosphere, and the horizontal strain is assumed to be independent of depth. When realistic tectonic forces (>1011 N/m) are applied, the rheological boundaries mainly control the emplacement of magma. The emplacement is expected at the MOHO, the upper–lower crust boundary, and the brittle–ductile boundary. For lower tectonic forces (<1011 N/m), the tectonic stress no longer plays an important role in the emplacement of magmas. When the tectonic stress controls the emplacement, the roles of rheological boundaries strongly depend on the surface heat flow. When the surface heat flow is relatively high (>80 mW/m2), the stress in the mantle is quite low and the MOHO cannot trap ascending magmas. For relatively low heat flow (<80 mW/m2), on the other hand, the MOHO acts as a magma trap, and the upper–lower crust boundary acts as a magma trap only when the magma supply rate is sufficiently high. Our results suggest that the emplacement depth can change responding to the change in the tectonic force and/or that in the surface heat flow. This may provide us a key to understand the relation between the evolution of a volcanic region and its tectonic and/or thermal history. 相似文献