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Subduction Initiation by Plume‐Plateau Interaction: Insights From Numerical Models
Geochemistry, Geophysics, Geosystems ( IF 4.480 ) Pub Date : 2020-07-06 , DOI: 10.1029/2020gc009119
Marzieh Baes 1 , Stephan V. Sobolev 1, 2 , Taras Gerya 3 , Sascha Brune 1, 2
Affiliation  

It has recently been demonstrated that the interaction of a mantle plume with sufficiently old oceanic lithosphere can initiate subduction. However, the existence of large lithospheric heterogeneities, such as a buoyant plateau, in proximity to a rising plume head may potentially hinder the formation of a new subduction zone. Here, we investigate this scenario by means of 3‐D numerical thermomechanical modeling. We explore how plume‐lithosphere interaction is affected by lithospheric age, relative location of plume head and plateau border, and the strength of the oceanic crust. Our numerical experiments suggest four different geodynamic regimes: (a) oceanic trench formation, (b) circular oceanic‐plateau trench formation, (c) plateau trench formation, and (d) no trench formation. We show that regardless of the age and crustal strength of the oceanic lithosphere, subduction can initiate when the plume head is either below the plateau border or at a distance less than the plume radius from the plateau edge. Crustal heterogeneity facilitates subduction initiation of old oceanic lithosphere. High crustal strength hampers the formation of a new subduction zone when the plume head is located below a young lithosphere containing a thick and strong plateau. We suggest that plume‐plateau interaction in the western margin of the Caribbean could have resulted in subduction initiation when the plume head impinged onto the oceanic lithosphere close to the border between plateau and oceanic crust.

中文翻译:

羽-高原相互作用的俯冲引发:数值模型的启示

最近已经证明,地幔柱与足够古老的海洋岩石圈的相互作用可以引发俯冲。但是,在上升的羽状喷头附近存在较大的岩石圈非均质性,例如浮力高原,可能会阻碍新的俯冲带的形成。在这里,我们通过3D数值热力学建模来研究这种情况。我们探讨了岩石圈与岩石圈之间的相互作用如何受到岩石圈年龄,柱头与高原边界的相对位置以及洋壳强度的影响。我们的数值实验提出了四种不同的地球动力学机制:(a)海洋沟槽形成,(b)圆形海洋高原沟槽形成,(c)高原沟槽形成,和(d)无沟槽形成。我们表明,无论海洋岩石圈的年龄和地壳强度如何,当羽流头位于高原边界以下或距离高原边缘的羽流半径小于一定距离时,俯冲就可以开始。地壳异质性促进了旧海洋岩石圈的俯冲作用。当羽状头位于年轻的岩石圈以下时,高地壳强度会阻碍新的俯冲带的形成,而岩石圈包含厚而强的高原。我们认为,当羽状头撞击到高原和大洋壳之间边界附近的海洋岩石圈时,加勒比西部边缘的羽-高原相互作用可能导致俯冲作用开始。当羽流头部低于高原边界或距离高原边缘的羽流半径小于一定距离时,就可能开始俯冲。地壳异质性促进了旧海洋岩石圈的俯冲作用。当羽状头位于年轻的岩石圈以下时,高地壳强度会阻碍新的俯冲带的形成,而岩石圈包含厚而强的高原。我们认为,当羽状头撞击到高原和大洋壳之间边界附近的海洋岩石圈时,加勒比西部边缘的羽-高原相互作用可能导致俯冲作用开始。当羽流头部低于高原边界或距离高原边缘的羽流半径小于一定距离时,就可能开始俯冲。地壳异质性促进了旧海洋岩石圈的俯冲作用。当羽状头位于年轻的岩石圈以下时,高地壳强度会阻碍新的俯冲带的形成,而岩石圈包含厚而强的高原。我们认为,当羽状头撞击到高原和大洋壳之间边界附近的海洋岩石圈时,加勒比西部边缘的羽-高原相互作用可能导致俯冲作用开始。当羽状头位于年轻的岩石圈以下时,高地壳强度会阻碍新的俯冲带的形成,而岩石圈包含厚而强的高原。我们认为,当羽状头撞击到高原和大洋壳之间边界附近的海洋岩石圈时,加勒比西部边缘的羽-高原相互作用可能导致俯冲作用开始。当羽状头位于年轻的岩石圈以下时,高地壳强度会阻碍新的俯冲带的形成,而岩石圈包含厚而强的高原。我们认为,当羽状头撞击到高原和大洋壳之间边界附近的海洋岩石圈时,加勒比西部边缘的羽-高原相互作用可能导致俯冲作用开始。
更新日期:2020-08-14
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