瑞士苏黎世联邦理工学院Ana Lorena Abila的一项最新研究报道了粘性俯冲界面强度的全球性汇编。这一研究成果于2024年10月14日发表在国际顶尖学术期刊《地质学》上。

据了解，俯冲带的长期和短期动力学受界面流变学的强烈影响。目前学术界对界面粘度的估计是基于端元流动定律或简单的混合模型，但理论上，俯冲界面上可能物质的变化允许粘度变化高达五个数量级。

为了更好地限制深/粘俯冲界面的强度范围，研究团队编制了一个全球数据库，其中包括折返深俯冲界面混杂剪切带中的岩石类型和块体及基质分布数据。研究人员对每个剪切带都进行了数值剪切实验，以量化它们的整体剪切强度/粘度。结果表明，自然俯冲剪切带的黏度范围为约10¹⁸-10²⁰pa^.S，剪切强度为约1100MPa。

研究人员称，它们之间的变化主要受温度控制，但即使是在相同温度下变形的剪切带，也可以观察到高达50倍的变化。这些变化被归因于基质成分、剪切带宽度和嵌段分布的差异。研究结果与古弹性测量和力平衡得出的界面强度估计一致，证实了地质输入的变化及其沿界面的空间分布对俯冲动力学的重要性。

附：英文原文

Title: Strength of viscous subduction interfaces: A global compilation

Author: Ana Lorena Abila, Whitney M. Behr, Jonas Ruh

Issue&Volume: 2024-10-14

Abstract: The long- and short-term dynamics of subduction zones are strongly affected by interface rheology. Current estimates of interface viscosity are based on endmember flow laws or simple mixing models, but the variation of possible materials on the subduction interface theoretically permits viscosity variations of up to five orders of magnitude. To better constrain the range of strength along deep/viscous subduction interfaces, we compiled a global database of rock types and block-and-matrix distributions in exhumed deep subduction interface mélange shear zones. We applied numerical shear experiments to each shear zone to quantify their bulk shear strengths/viscosities. Our results show that natural subduction shear zones have viscosities ranging from ～10¹⁸ to 10²⁰ Pas and shear strengths of ～1100 MPa. The variation among them is dominantly controlled by temperature, but even for shear zones deformed at the same temperature, variations of up to a factor of 50 are observed. These variations are attributed to differences in matrix composition, shear zone width, and block distributions. Our results are consistent with paleopiezometric and force-balancederived estimates of interface strength, and they confirm the importance of variation in geological inputs and their spatial distribution along the interface for subduction dynamics.

DOI: 10.1130/G52518.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52518.1/649223/Strength-of-viscous-subduction-interfaces-A-global