Geological records of transient fluid drainage into the shallow mantle wedge.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37018395.
- Also identified by DOI 10.1126/sciadv.ade6674 and PMC identifier 10075964.
- Licence recorded as CC BY-NC.
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Abstract
Pore fluid pressure on subduction zone megathrusts is lowered by fluid drainage into the overlying plate, affecting subduction zone seismicity. However, the spatial and temporal scales of fluid flow through suprasubduction zones are poorly understood. We constrain the duration and velocity of fluid flow through a shallow mantle wedge based on the analyses of vein networks consisting of high-temperature serpentine in hydrated ultramafic rocks from the Oman ophiolite. On the basis of a diffusion model and the time-integrated fluid flux, we show that the channelized fluid flow was short-lived (2.1 × 10<sup>-1</sup> to 1.1 × 10<sup>1</sup> years) and had a high fluid velocity (2.7 × 10<sup>-3</sup> to 4.9 × 10<sup>-2</sup> meters second<sup>-1</sup>), which is close to the propagation velocities of seismic events in present-day subduction zones. Our results suggest that the drainage of fluid into the overlying plate occurs as episodic pulses, which may influence the recurrence of megathrust earthquakes.