浅地幔系统的组成和属性相态
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本文为国家自然科学基金资助项目(编号:41574111)的成果。


On composition, attributes andphases of the shallow- mantle system
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    摘要:

    板块构造学说根据构造的活动性划分单元,不考虑单元是否同质。浅地幔系统考虑了系统组成单元的异质性和动力来源,适合于系统的能量和物质运动总体规律的研究。把地球系统地划分为地球表面、浅地幔、地幔对流和地核四个子系统,地球系统就完整了。浅地幔子系统由四个不同质的的单元相互作用组成,它们是大洋岩石圈、大陆岩石圈、洋陆转换带岩石圈和软流圈,它们是不同质的。地震层析成像结果支持这种单元划分。系统作用反映了大洋岩石圈与大陆岩石圈的相互博弈,洋陆转换带是洋底扩张和大陆增生之间博弈的主要战场和阻尼器。软流圈是地幔对流的顶层,也是系统的能量库和主要动力来源。在深度200 km以下,软流圈的物质运动已经与板块运动模式分离。软流圈物质运动主要是大尺度的蠕动,也包括流体的析出和渗透,局部岩浆的集结和上涌。岩石圈板块浮在蠕动的软流圈之上,软流圈地幔的热流体可以通过岩石圈地幔黏度较小的区域向上渗透。同时,在重力作用下,岩石圈黏度大的物质也可以向下运动,拆沉到软流圈底部。从目前的成像结果可以看到,对于地球表面难以观察的软流圈和地下深部,对比三维的地震波速和电阻率扰动图像,可以获得关于物质运动的信息,认知已经发生在地壳和上地幔的物质运动特征。

    Abstract:

    Plate tectonics divides the tectonic units according to the activity of the structure, regardless of whether the units belong to dissimilarity matters. The shallow mantle subsystem takes into account the dissimilarity and motion dynamic sources of the system elements, and is suitable for the study of the Earth system. By dividing the Earth system into four subsystems: the Earth’s surface, the shallow mantle, the mantle convection and the core, the Earth system is viewed in entirety. The shallow mantle system consists of four heterogeneous elements with different mass interactions, they are the ocean lithosphere, the continental lithosphere, the ocean—continent transition zones and the asthenosphere. The current seismic tomography images support this division of the elements. The systematic actions reflects the mutual game between the ocean lithosphere and the continental lithosphere, and the ocean—continent transition zones act as the main battlefield between the expansion of the ocean floors and the accretion of the continental continent. The asthenosphere is the top layer of the mantle convection and is also the system’s energy reservoir and main power source. At a depth of less than 200 km, the material motion in the asthenosphere has been different from the plate motion pattern. The matter movement where is mainly large- scale creeping, including fluid extraction and permeation, local magma build- up and upwelling. The lithosphere plate floats above the peristaltic asthenosphere, and the hot fluid in the asthenosphere penetrates upward through breaks with lower viscosity of the lithosphere. At the same time, under the action of gravitation force, the lithosphere material can also move downwards, underplating to the bottom of the asthenosphere. From the current imaging results, we can find clear information about the movement of matter in the shallow mantle by compared with three- dimensional seismic wave velocity and resistivity perturbation images, and understand cognitive characteristics of the material movement.

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引用本文

杨文采.2020.浅地幔系统的组成和属性相态[J].地质论评,66(2):263-275,[DOI].
YANG Wencai.2020. On composition, attributes andphases of the shallow- mantle system[J]. Geological Review,66(2):263-275.

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  • 收稿日期:2019-12-08
  • 最后修改日期:2020-02-06
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  • 在线发布日期: 2020-03-16
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