中国科学院朱明帅及其研究小组探索了微大陆在俯冲启动中的作用。相关论文于2023年5月16日发表在《地质学》杂志上。

在本文中，研究人员通过二维热力数值模拟，探索了微大陆在俯冲启动中的作用，并考虑了围绕微大陆的海洋地壳年龄不同的三种情况，对微大陆的特征(尺寸、地壳厚度、温度梯度和流变学)、海洋板块年龄和收敛速度进行了参数化检验。结果表明，中等大小(≥300km)的微大陆可以在大陆板块和海洋板块交界处引发俯冲。大部分微大陆将被拖入俯冲带，随后的软流圈上涌将结合微大陆的一部分。

数值模型为俯冲的开始增加了一个新的假设场景，特别是对那些年轻且有浮力的板块俯冲到较老且密度较大的海洋板块之下的地方。此外，它们还能解释超俯冲带蛇绿岩中外来地壳物质和超高压矿物的来源。

据悉，俯冲开始是板块构造中的一个关键过程。俯冲的初始化模型包括被动边缘的坳陷，海洋转换断层，海洋核心复合物的反演和洋脊断裂，但这一模型忽略了大陆地壳残余在海洋地壳中的潜在影响。

附：英文原文

Title: Do microcontinents nucleate subduction initiation

Author: Mingshuai Zhu, Zhiyong Yan, Daniel Pastor-Galán, Lin Chen, Laicheng Miao, Fuqin Zhang, Shun Li, Shunhu Yang

Issue&Volume: 2023-05-16

Abstract: Subduction initiation is a pivotal process in plate tectonics. Models of subduction initiation include the collapse of passive margins, oceanic transform faults, inversion of oceanic core complexes, and ridge failure but have ignored the potential effects of continental crust relicts within the oceanic crust. In this paper, we explore the role of microcontinents on subduction initiation through two-dimensional thermo-mechanical numerical modeling. We consider three scenarios with variable ages of oceanic crust surrounding the microcontinent and parametrically examine the microcontinent characteristics (size, crustal thickness, thermal gradient, and rheology), oceanic plate age, and convergence rates. Results suggest that moderate-size (≥300 km) microcontinents can nucleate subduction initiation at the junction between continental and oceanic plates. A large part of the microcontinent would be dragged into the subduction zone, and the subsequent asthenosphere upwellings would incorporate part of the microcontinent. Our numerical models add a new hypothetical scenario for subduction initiation, especially for those places where a young and buoyant plate subducts beneath an older and denser oceanic plate. Moreover, they can explain the origin of exotic crust materials and ultrahigh-pressure minerals in supra–subduction zone ophiolites.

DOI: 10.1130/G51222.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G51222.1/623409/Do-microcontinents-nucleate-subduction-initiationredirectedFrom=fulltext