Revisiting the geodynamics of the Middle East region from an integrated geophysical perspective

IF 2.1 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
Chiara Civiero , Nicolas L. Celli , Magdala Tesauro
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引用次数: 0

Abstract

A long-standing question in geodynamics is whether mantle flow is driven by the plate motion alone, or mantle upwelling makes a significant contribution to it. Subducting slabs and lateral variations of the continental lithosphere can further influence the asthenospheric flow and control its direction. The Middle East region (MER) is a complex continental setting where different processes such as rifting, break-up, plate collision, and tectonic escape kinematically interact with each other. In this context, the role that lithospheric structure, mantle flow, and active upwellings may play is debated. Tomographic images provide a snapshot of the current thermal conditions of a region and seismic anisotropy can also help resolve mantle convection. Here, we synthesize shear-wave splitting observations together with up-to-date tomography models of the mantle structure beneath the MER and other geophysical data. Low-velocity anomalies are seen at asthenospheric depths beneath W Arabia, NW Iran, and Anatolia, suggesting a spreading zone of warm mantle. Two deep low-velocity bodies in Afar and Levant –interpreted as hot mantle plumes– are the sources of this shallower mantle flow. Where low velocities are imaged, we observe predominantly NE–SW oriented anisotropy, anomalously high topography, and abundant basaltic volcanism. The integrated analysis suggests that a horizontal component associated with active upwelling is present in the upper-mantle flow field. The large-scale circulation flow fed by the Afar and Levant Plumes, aided by the subduction-induced forces, facilitates the lateral motion of the Anatolian microplate and affects the dynamic evolution of the Zagros orogen. The proposed scenario demonstrates that the interplay between plate-tectonic events and mantle dynamics controls the kinematics of the region and can explain the general patterns of deformation observed at the surface.

从综合地球物理角度重新审视中东地区的地球动力学
地球动力学中一个长期存在的问题是,地幔流动是由板块运动单独驱动的,还是地幔上升流对其有重要贡献。俯冲板块和大陆岩石圈的横向变化进一步影响软流圈流动并控制其方向。中东地区(MER)是一个复杂的大陆环境,不同的过程,如裂陷、破裂、板块碰撞和构造逃逸,在运动学上相互作用。在这种背景下,岩石圈结构、地幔流动和活跃的上升流可能发挥的作用是有争议的。层析成像提供了一个区域当前热状况的快照,地震各向异性也可以帮助解决地幔对流问题。在这里,我们将剪切波分裂观测结果与最新的MER下地幔结构层析成像模型和其他地球物理数据综合起来。在阿拉伯半岛西部、伊朗西北部和安纳托利亚的软流圈深处可见低速异常,表明存在暖地幔扩张带。位于阿法尔和黎凡特的两个深层低速体——被解释为热地幔柱——是这种浅层地幔流的来源。在低速成像的地方,我们观察到主要是东北-西南向的各向异性,异常高的地形和丰富的玄武岩火山活动。综合分析表明,上地幔流场存在与活跃上升流相关的水平分量。由阿法尔和累范特地幔柱提供的大规模环流流,在俯冲力的辅助下,促进了安纳托利亚微板块的横向运动,影响了扎格罗斯造山带的动态演化。所提出的情景表明,板块构造事件和地幔动力学之间的相互作用控制了该地区的运动学,并可以解释在地表观测到的一般变形模式。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Geodynamics
Journal of Geodynamics 地学-地球化学与地球物理
CiteScore
4.60
自引率
0.00%
发文量
21
审稿时长
6-12 weeks
期刊介绍: The Journal of Geodynamics is an international and interdisciplinary forum for the publication of results and discussions of solid earth research in geodetic, geophysical, geological and geochemical geodynamics, with special emphasis on the large scale processes involved.
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