Study on lithogeochemistry of Middle Jurassic basalts from southern China represented by the Fankeng basalts from Yongding of Fujian Province   总被引：3，自引：1，他引：3  

ZHOU Jincheng  JIANG Shaoyong  WANG Xiaolei  YANG Jinghong  ZHANG Mengqun 《中国科学D辑(英文版)》2006,49(10):1020-1031

There exists an E-W trending Middle Jurassic volcanic zone in southern China. The Fankeng basalts in the Yongding basin of Fujian Province are considered to be a typical example. The Fankeng basalts have TiO2 contents in the range of 1.92%-3.21%. They are classified as high-Ti basalts. They also have higher total Fe (averaging FeO* = 11.09%). The Middle Jurassic Fankeng basalts from southwestern Fujian have obvious distinctive lithogeochemical features from early Cre- taceous basalts from southeastern coast of China. They have higher HFSE, such as Th, Nb, Ta, Zr and Ti. Their element ratios related with HFSE, such as Zr/Ba, La/Nb, La/Ta ,Zr/Y, Ti/Y, Ba/Nb, K/Ti and Rb/Zr are similar to those of OIB. The most samples have ε Nd(T) of-0.70-0.24, which are near chondrite. Some samples have higher ε Nd(T) of 1.87-3.55.Therefore, these basaltic magmas might be derived from depleted asthenospheric mantle. The lithogeochemical characteristics of the Fankeng basalts may be caused by interaction between asthenosphere and lithosphere at the time. The (Early-) Middle Jurassic basalts and gabbros from southeastern Hunan, southern Jiangxi and northern Guangdong provinces show similar geochemical features to those of the Fankeng basalts from the Yongding of Fujian. Occurrence of these OIB-type basalts in the area may be regarded as the petrological mark of upwelling of asthenosphere at the time. Upwelling of asthenosphere has led to tectonic extension and the formation of rifted basin in the area.  相似文献   

华北地区深部构造特征   总被引：5，自引：0，他引：5  

邢作云  邢集善  赵斌 《地质科技情报》2006,25(6):17-23,36

通过岩石圈厚度变化、大地热流值和莫霍面起伏,结合浅表岩浆构造活动,编制了华北地区深部构造略图,建立了燕山期软流圈上涌与岩浆构造活动的关系模式,总结了该区的深部构造特征:岩石圈厚区与软流圈上涌区共存.同时,按生成机制对该区软流圈上涌进行了类型划分:中生代燕山期(J-K1)、早新生代(E2-E3)主动机制形成的软流圈上涌,中、新生代(K2-E1)及晚新生代(N-Q)被动机制形成的软流圈上涌.  相似文献   

Effect of lateral viscosity variations in the top 300 km on the geoid and dynamic topography   总被引：2，自引：0，他引：2  

O. &#;adek  L. Fleitout 《Geophysical Journal International》2003,152(3):566-580

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青藏高原大陆动力学研究——“INDEPTH”合作研究的体会   总被引：1，自引：1，他引：0  

赵文津  冯昭贤 《地球学报》1996,17(2):119-128

“NDEPTH”是中国和美国地学家合作开展的大陆动力学研究项目。本文介绍了研究该项目的重大意义、长远的战略目标和酝酿协议过程,喜马拉雅造山带和青藏高原新一轮研究的科学目标、研究工作方针和研究工作特点;最后对组织管理工作提出了几点建议。  相似文献   

The crustal and upper-mantle geophysical signature of narrow continental rifts in the Pannonian basin   总被引：1，自引：0，他引：1  

A. Ádám  & M. Bielik 《Geophysical Journal International》1998,134(1):157-171

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Thin-sheet modelling of lithospheric deformation and surface mass transport   总被引：1，自引：0，他引：1  

Ivone Jimnez-Munt  Daniel Garcia-Castellanos  Manel Fernandez 《Tectonophysics》2005,407(3-4):239-255

We study the effects of incorporating surface mass transport and the gravitational potential energy of both crust and lithospheric mantle to the viscous thin sheet approach. Recent 2D (cross-section) numerical models show that surface erosion and sediment transport can play a major role in shaping the large-scale deformation of the crust. In order to study these effects in 3D (planform view), we develop a numerical model in which both the dynamics of lithospheric deformation and surface processes are fully coupled. Deformation is calculated as a thin viscous layer with a vertically-averaged rheology and subjected to plane stresses. The coupled system of equations for momentum and energy conservation is solved numerically. This model accounts for the isostatic and potential-energy effects due to crustal and lithospheric thickness variations. The results show that the variations of gravitational potential energy due to the lateral changes of the lithosphere–asthenosphere boundary can modify the mode of deformation of the lithosphere. Surface processes, incorporated to the model via a diffusive transport equation, rather than just passively reacting to changes in topography, play an active role in controlling the lateral variations of the effective viscosity and hence of the deformation of the lithosphere.  相似文献   

软流层部分熔融岩浆竖向迁移模型分析   总被引：1，自引：0，他引：1  

董军  彭省临  赖健清  邵拥军 《高校地质学报》2002,8(1):16-24

针对地幔蠕动过程中，软流层部分熔融岩浆上升这一地质背景，从力学的基本原理出发，将软流层岩石抽象为一类充满液体的多孔介质，并假定其以均匀速度上升，对岩石中部分熔融岩浆的迁移机理进行了分析，得到了一组简化的公式，并进行了计算。结果表明在此简化模型下，可以得到一个临界速度值的表达式。当岩石上升的速度低于该临界数值时，部分熔融岩浆将在一定的界面上形成；若大于这个临界数值，部分熔融岩浆的形成将滞后到一段竖向区域内完成。同时简单的计算结果也说明部分熔融岩浆的迁移运动是实现热量及成矿物质元素向上迁移的重要原因。其结果和某些岩浆过程的地质分析是一致的，这对进一步研究地幔蠕动及其成矿动力学具有重要的意义。  相似文献   

A Tertiary asthenospheric flow beneath the southern French Massif Central indicated by upper mantle seismic anisotropy and related to the west Mediterranean extension   总被引：1，自引：0，他引：1  

Guilhem Barruol  Michel Granet 《Earth and Planetary Science Letters》2002,202(1):31-47

Upper mantle flow beneath the French Massif Central is investigated using teleseismic shear wave splitting induced by seismic anisotropy. About 25 three-component stations (short period, intermediate and broadband) were installed during the period 1998-1999 in the southern Massif Central, from the Clermont Ferrand volcanic area to the Mediterranean Sea. Teleseismic shear waves (SKS, SKKS and PKS) were used to determine the splitting parameters: the fast polarization direction and the delay time. Delay times ranging between 0.7 and 1.5 s have been observed at most of the sites. The azimuths of the fast split shear waves trend homogeneously NW-SE in the southern Massif Central suggesting a homogeneous mantle flow beneath this area. The observed NW-SE direction differs from the N100°E Pyrenean anisotropy further south. It does not appear to be correlated to Hercynian structures nor to the present-day motion of the plate but is well correlated to the Tertiary extension direction. We propose that the opening of the western Mediterranean induced by the rotation of the Corsica-Sardinia lithospheric block and the roll-back to the SE of the Tethys slab may have generated a large asthenospheric mantle flow beneath the southern Massif Central and a deflection of the up going plume centered beneath the northern Massif Central toward the SE.  相似文献   

拆沉作用(delamination)及其壳—幔演化动力学意义   总被引：45，自引：0，他引：45  

高山  金振民 《地质科技情报》1997,(1)

拆沉作用导致下地壳和岩石圈地幔下沉，相应软流圈上涌至壳—幔边界，使下地壳、岩石圈地幔和软流圈三者发生物质交换，引起岩浆作用、山脉隆升、伸展、垮塌，形成坳陷盆地，并最终使大陆地壳向长英质方向演化，产生与其它行星不同的、独一无二的中性安山质或英云闪长质成分。拆沉作用是对经典板块构造理论的重要补充与完善  相似文献   

动态部分熔融作用及其地球物理意义   总被引：7，自引：1，他引：7  

金振民  白武明 《地质科技情报》1993,12(1):93-100

本文着重阐述了上地幔动态部分熔融动力学的几个基本问题:(1)初始熔融物的产生;(2)渗透和萃取;(3)运移和聚集;(4)研究方法、内容及其地球物理意义。笔者强调指出,在初始熔融阶段,两面角是控制上地幔熔融物的几何分布、渗透性和连通性能的关键参数,少量熔融物(2%~5%)不仅会使软流圈中地震波速下降、导电率增加,而且还引起上地幔非弹性衰减现象。  相似文献