Crustal Growth by Magmatic Accretion Constrained by Metamorphic P-T Paths and Thermal Models of the Kohistan Arc, NW Himalayas   总被引：2，自引：0，他引：2  

YOSHINO  TAKASHI; OKUDAIRA  TAKAMOTO 《Journal of Petrology》2004,45(11):2287-2302

Magmatic accretion is potentially an important mechanism inthe growth of the continental crust and the formation of granulites.In this study, the thermal evolution of a magmatic arc in responseto magmatic accretion is modeled using numerical solutions ofthe one-dimensional heat conduction equation. The initial andboundary conditions used in the model are constrained by geologicalobservations made in the Kohistan area, NW Himalayas. Takingconsideration of the preferred intrusion locations for basalticmagmas, we consider two plausible modes of magmatic accretion:the first involves the repeated intrusion of basalt at mid-crustaldepths (‘intraplate model’), and the second evaluatesthe simultaneous intrusion of basalt and picrite at mid-crustaldepths and the base of the crust respectively (‘double-platemodel’). The results of the double-plate model accountfor both the inferred metamorphic P–T paths of the Kohistanmafic granulites and the continental geotherm determined frompeak P–T conditions observed for granulite terranes. Thedouble-plate model may be applicable as a key growth processfor the production of thick mafic lower crust in magmatic arcs. KEY WORDS: thermal model; magmatic underplating; P–T path; granulite; lower crust  相似文献   

Structure and thermal regime beneath the South Pole region, East Antarctica, from magnetotelluric measurements     

Philip E. Wannamaker  John A. Stodt  Louise Pellerin  Steven L. Olsen  Darrell B. Hall 《Geophysical Journal International》2004,157(1):36-54

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利用热红外温差识别沙尘   总被引：3，自引：2，他引：3  

延昊  侯英雨  刘桂清  何延波 《遥感学报》2004,8(5):471-474

沙尘识别是沙尘灾害监测和沙尘气溶胶特性研究的首要工作。利用辐射传输方程进行了沙尘气溶胶的辐射计算 ,对不同沙尘气溶胶光学厚度下的热红外通道温差ΔT(T11μm-T12 μm)的变化进行了分析。理论分析表明 ,利用热红外通道的温度差ΔT进行陆地沙尘识别是可行的。并利用NOAA AVHRR热红外通道的温度差ΔT进行了陆地沙尘识别的实验 ,经与地面气象站实测的沙尘天气现象相比较 ,结果一致。  相似文献   

Gross thermodynamics of two-component core convection     

David Gubbins  Dario Alfè  Guy Masters  G. David Price  Michael Gillan 《Geophysical Journal International》2004,157(3):1407-1414

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Thermal structure, coupling and metamorphism in the Mexican subduction zone beneath Guerrero   总被引：2，自引：0，他引：2  

V. C. Manea  M. Manea  V. Kostoglodov  C. A. Currie  G. Sewell 《Geophysical Journal International》2004,158(2):775-784

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Nonlinear free thermal convection in a spherical shell:A variable viscosity model     

朱涛  冯锐 《地震学报(英文版)》2005,18(2):206-217

Introduction The velocity field of surface plate motion can be split into a poloidal and a toroidal parts.At the Earth′s surface,the toroidal component is manifested by the existence of transform faults,and the poloidal component by the presence of convergence and divergence,i.e.spreading and subduc-tion zones.They have coupled each other and completely depicted the characteristics of plate tec-tonic motions.The mechanism of poloidal field has been studied fairly clearly which is related to …  相似文献   

Thermal evolution of an extensional detachment as constrained by organic metamorphic data and thermal modeling: Graz Paleozoic Nappe Complex (Eastern Alps)   总被引：1，自引：0，他引：1  

Gerd Rantitsch  Reinhard F. Sachsenhofer  Christian Hasenhüttl  Barbara Russegger  Thomas Rainer 《Tectonophysics》2005,411(1-4):57-72

Following Early Cretaceous nappe stacking, the Eastern Alps were affected by late-orogenic extension during the Late Cretaceous. In the eastern segment of this range, a Late Cretaceous detachment separates a very low- to low-grade metamorphic cover (Graz Paleozoic Nappe Complex, GPNC) above a low- to high-grade metamorphic basement. Synchronously, the Kainach Gosau Basin (KGB) collapsed and subsided on top of the section.Metamorphism of organic material within this section has been investigated using vitrinite reflectance data and Raman spectra of extracted carbonaceous material. In the southern part of the GPNC, vitrinite reflectance indicates a decrease in organic maturity towards the stratigraphic youngest unit. The remaining part of the GPNC is characterized by an aureole of elevated vitrinite reflectance values and Raman R2 ratios that parallels the margins of the GPNC. Vitrinite reflectance in the KGB shows a steep coalification gradient and increases significantly towards the western basin margin. The observed stratigraphic trend in the southern GPNC is a result of deep Paleozoic to Early Cretaceous burial. This maturity pattern was overprinted along the margins by advective heat and convective fluids during Late Cretaceous to Paleogene exhumation of basement rocks.During shearing, the fault zone was heated up to ca. 500 °C. This overprint is explained by a two-dimensional thermal model with a ramp-flat fault geometry and a slip rate of 1 to 1.5 cm/year during 5 Ma fault movement. The collapse basin above the detachment subsided in a thermal regime which was characterized by relaxing isotherms.  相似文献   

甘肃春季(3～5月)沙尘暴成因分析   总被引：3，自引：7，他引：3  

郭慧  王式功  李栋梁  冯建英  陆登荣  张存杰 《中国沙漠》2005,25(3):412-416

甘肃春季(3～5月)沙尘暴小波变换分析清楚地反映了甘肃春季沙尘暴不同时间尺度周期振荡的交替作用。甘肃中西部自20世纪80年代以来变暖,其变暖与太阳黑子周期长度(SCL)密切相关。甘肃春季沙尘暴与甘肃中西部热力因子和降水研究表明,当冬季冷空气活动频繁,春季气温回升快,气温波动幅度大,降水偏少,甘肃春季容易发生沙尘暴。  相似文献   

A new bounding surface model for thermal cyclic behaviour          下载免费PDF全文

C. Zhou  K.Y. Fong  C.W.W. Ng 《国际地质力学数值与分析法杂志》2017,41(16):1656-1666

To accurately predict soil volume changes under thermal cycles is of great importance for analysing the performance of many earth structures such as the energy pile and energy storage system. Most of the existing thermo‐mechanical models focus on soil behaviour under monotonic thermal loading only, and they are not able to capture soil volume changes under thermal cycles. In this study, a constitutive model is proposed to simulate volume changes of saturated soil subjected to cyclic heating and cooling. Two surfaces are defined and used: a bounding surface and a memory surface. The bounding surface and memory surface are mainly controlled by the preconsolidation pressure (a function of plastic volumetric strain) and the maximum stress experienced by the soil, respectively. Under thermal cycles, the distance of the two surfaces and plastic modulus increase with an accumulation of plastic strain. By adopting the double surface concept, a new elastoplastic model is derived from an existing single bounding surface thermo‐mechanical model. Comparisons between model predictions and experimental results reveal that the proposed model is able to capture soil volume changes under thermal cycles well. The plastic strain accumulates under thermal cycles, but at a decreasing rate, until stabilization. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

近20年京津唐主体城区地表热场空间特征变化分析   总被引：3，自引：1，他引：2  

于琛  胡德勇  张旸  曹诗颂  段欣  张亚妮 《地理科学》2019,39(6):1016-1024

基于Landsat遥感影像获取京津唐主体城区1995~2015年地表温度(Land Surface Temperature, LST)和不透水地表盖度(Impervious Surface Percentage, ISP)数据。采用热点聚集和阈值分割法,依据地表的温度和不透水盖度属性将京津唐主体城区划分成9种地表热场类型,分析并探讨地表热场的发展规律、年际变化状况和区域贡献作用。研究发现,京津唐主体城区地表温度与不透水地表盖度间存在显著的正向相关关系,两者分别呈现“阶梯降”和“两端高、中间低”的变化特征。京津唐主体城区地表热场的发展主轴保持在西北-东南方向,且随时间推移沿主轴呈聚集态势。 京津唐主体城区地表热场的影响范围在空间上持续扩张,对于不同的主体城区,其在整体区域的热场贡献中有差异化表现。  相似文献