Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier

McGary, R. Shane; Evans, Robert; Wannamaker, Philip E.; Elsenbeck, Jimmy; Rondenay, S.

doi:10.1038/nature13493

Cited by 143 publications

(169 citation statements)

References 36 publications

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“…Based on a 2‐D model of Cascadia, McGary et al . [] revealed a fluid/melt pathway similar with that in profile B–B′ of our model. They interpreted that the primary source existed at the slab surface at about 100 km depth.…”

Section: Discussionsupporting

confidence: 73%

Electrical image of subduction zone beneath northeastern Japan

et al. 2015

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We conducted long‐period magnetotelluric observations in northeastern Japan from 2010 to 2013 to investigate the three‐dimensional electrical resistivity distribution of the subduction zone. Incorporating prior information of the subducting slab into the inversion scheme, we obtained a three‐dimensional resistivity model in which a vertically continuous conductive zone is imaged from the subducting slab surface to the lower crust beneath the Ou Backbone Range. The conductive body indicates a saline fluid and/or melt pathway from the subducting slab surface to the lower crust. The lower crust conductor is less than 10 Ω m, and we estimate a saline fluid and/or melt fraction of at least 0.7 vol. %. Other resistivity profiles in the across‐arc direction reveal that the conductive body segregates from the subducting slab surface at 80–100 km depth and takes an overturned form toward the back arc. The head of the conducting body reaches the lower crust just beneath Mt. Gassan, one of the prominent back‐arc volcanoes in the system.

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Section: Discussionsupporting

confidence: 73%

Electrical image of subduction zone beneath northeastern Japan

et al. 2015

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“…5b) is interpreted as pervasive serpentinization of the forearc mantle wedge (mainly antigorite). These findings are consistent with electrical resistivity studies in the forearc of Cascadia (McGary et al, 2014;Soyer and Unsworth, 2006) and point to…”

Section: Accepted Manuscriptsupporting

confidence: 81%

Teleseismic constraints on the geological environment of deep episodic slow earthquakes in subduction zone forearcs: A review

2016

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More than a decade after the discovery of deep episodic slow slip and tremor, or slow earthquakes, at subduction zones, much research has been carried out to investigate the structural and seismic properties of the environment in which they occur. Slow earthquakes generally occur on the megathrust fault some distance downdip of the great earthquake seismogenic zone in the vicinity of the mantle wedge corner, where three major structural elements are in contact: the subducting oceanic crust, the overriding forearc crust and the continental mantle. In this region, thermo-petrological models predict significant fluid production from the dehydrating oceanic crust and mantle due to prograde metamorphic reactions, and their consumption by hydrating the mantle wedge. These fluids are expected to affect the dynamic stability of the megathrust fault and enable slow slip by increasing pore-fluid pressure and/or reducing friction in fault gouges.Resolving the fine-scale structure of the deep megathrust fault and the in situ distribution of fluids where slow earthquakes occur is challenging, and most advances have been made using A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTteleseismic scattering techniques (e.g., receiver functions). In this paper we review the teleseismic structure of six well-studied subduction zones (three hot, i.e., Cascadia, southwest Japan, central Mexico, and three cool, i.e., Costa Rica, Alaska, and Hikurangi) that exhibit slow earthquake processes and discuss the evidence of structural and geological controls on the slow earthquake behavior. We conclude that changes in the mechanical properties of geological materials downdip of the seismogenic zone play a dominant role in controlling slow earthquake behavior, and that near-lithostatic pore-fluid pressures near the megathrust fault may be a necessary but insufficient condition for their occurrence.

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“…As a consequence of this regularization process, most MT inversions are smooth and do not resolve sharp contrasts and conductors are often smeared to depth (for a review on inversion, see, e.g., Pek and Santos 2006;Rodi and Mackie 2012; for approaches including sharp boundaries, see e.g. Smith et al 1999;McGary et al 2014).…”

Section: Introductionmentioning

confidence: 99%

On the Coupling of Geodynamic and Resistivity Models: A Progress Report and the Way Forward

Heise

Ellis

2015

Surv Geophys

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Magnetotelluric (MT) studies represent the structure of crust and mantle in terms of conductivity anomalies, while geodynamic modelling predicts the deformation and evolution of crust and mantle subject to plate tectonic processes. Here, we review the first attempts to link MT models with geodynamic models. An integration of MT with geodynamic modelling requires the use of relationships between conductivity and rheological parameters such as viscosity and melt fraction, which are provided by laboratory measurements of rock properties. Owing to present limitations in our understanding of these relationships, and in interpreting the trade-off between scale and magnitude of conductivity anomalies from MT inversions, most studies linking MT and geodynamic models are qualitative rather than providing hard constraints. Some recent examples attempt a more quantitative comparison, such as a study from the Himalayan continental collision zone, where rheological parameters have been calculated from a resistivity model and compared to predictions from geodynamic modelling. We conclude by demonstrating the potential in combining MT results and geodynamic modelling with examples that directly use MT results as constraints within geodynamic models of ore bodies and studies of an active volcano-tectonic rift.

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Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier

Cited by 143 publications

References 36 publications

Electrical image of subduction zone beneath northeastern Japan

Electrical image of subduction zone beneath northeastern Japan

Teleseismic constraints on the geological environment of deep episodic slow earthquakes in subduction zone forearcs: A review

On the Coupling of Geodynamic and Resistivity Models: A Progress Report and the Way Forward

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