研究人员在 Hikurangi 边缘进行的三维地震成像和海洋钻探显示，在俯冲的 Hikurangi 高原大火成岩省的广泛水合(体积高达 47% H2O)的火山上地壳中，存在一个广泛分布的、以前未知的流体储层。这个厚约 1.5 km 的火山碎屑上地壳很容易随着俯冲而脱水，但在到达具有明显缓慢滑动特征的区域时，仍保留了一半的流体含量。
研究人员认为，火山高原和海山富含火山碎屑的上地壳是构成俯冲带流体收支的主要水源，并可能驱动沿着巨型逆冲断层的流体超压，从而导致频繁的浅层缓慢滑动。
据介绍，许多沿着近海沟巨型逆冲断层的周期性缓慢滑动发生在俯冲带，但由于未知的原因，这一过程并不普遍存在。流体超压会导致缓慢滑动；然而，在自然系统中，人们对缓慢滑动、流体含量和水文地质学之间的联系仍然知之甚少。
附：英文原文
Title: Subducting volcaniclastic-rich upper crust supplies fluids for shallow megathrust and slow slip
Author: Andrew C. Gase, Nathan L. Bangs, Demian M. Saffer, Shuoshuo Han, Peter K. Miller, Rebecca E. Bell, Ryuta Arai, Stuart A. Henrys, Shuichi Kodaira, Richard Davy, Laura Frahm, Daniel H. N. Barker
Issue&Volume: 2023-08-16
Abstract: Recurring slow slip along near-trench megathrust faults occurs at many subduction zones, but for unknown reasons, this process is not universal. Fluid overpressures are implicated in encouraging slow slip; however, links between slow slip, fluid content, and hydrogeology remain poorly known in natural systems. Three-dimensional seismic imaging and ocean drilling at the Hikurangi margin reveal a widespread and previously unknown fluid reservoir within the extensively hydrated (up to 47 vol % H2O) volcanic upper crust of the subducting Hikurangi Plateau large igneous province. This ~1.5 km thick volcaniclastic upper crust readily dewaters with subduction but retains half of its fluid content upon reaching regions with well-characterized slow slip. We suggest that volcaniclastic-rich upper crust at volcanic plateaus and seamounts is a major source of water that contributes to the fluid budget in subduction zones and may drive fluid overpressures along the megathrust that give rise to frequent shallow slow slip.
DOI: adh0150
Source: https://www.science.org/doi/full/10.1126/sciadv.adh0150