Seafloor overthrusting causes ductile fault deformation and fault sealing along the Northern Hikurangi Margin

Morgan, Julia K.; Solomon, E. A.; Fagereng, Åke; Savage, H. M.; Wang, Maomao; Meneghini, Francesca; Barnes, Philip; Bell, Rebecca; French, M. E.; Bangs, N. L.; Kitajima, H.; Saffer, D. M.; Wallace, L. M.

doi:10.1016/j.epsl.2022.117651

Cited by 10 publications

(9 citation statements)

References 61 publications

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“…Some authors have suggested that SSEs that originate along the decollement at the base of the wedge are accompanied by slip diverted to thrust faults in the Hikurangi accretionary wedge (Shaddox & Schwartz, 2019). We expect SSEs to fracture the rocks, deform and cause granular flow along these thrust faults (Chen, 2023; Fagereng et al., 2019; Morgan et al., 2022). Our pre and post‐failure laboratory measurements suggest that these processes might increase the deeper prism permeability, where MT07 equivalent rocks may be present, by 2–3 orders of magnitude.…”

Section: Discussionmentioning

confidence: 99%

Permeability and Elastic Properties of Rocks From the Northern Hikurangi Margin: Implications for Slow‐Slip Events

Tisato,

Bland,

Van Avendonk

et al. 2024

Geophysical Research Letters

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Fluid flow and pore‐pressure cycling are believed to control slow slip events (SSEs), such as those that frequently occur at the northern Hikurangi margin of New Zealand. To better understand fluid flow in the forearc system we examined the relationship between several physical properties of Cretaceous‐to‐Pliocene sedimentary rocks from the Raukumara peninsula. We found that the permeability of the deep wedge is too low to drain fluids, but fracturing increases permeability by orders of magnitude, making fracturing key for fluid flow. In weeks to months, plastic deformation, swelling, and possibly not‐yet‐identified mechanisms heal the fractures, restoring the initial permeability. We conclude that overpressures at the northern HM might partly dissipate during SSEs due to enhanced permeability near faults. However, in the months following an SSE, healing in the prism will lower permeability, forcing pore pressure to rise and a new SSE to occur.

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Section: Discussionmentioning

confidence: 99%

Permeability and Elastic Properties of Rocks From the Northern Hikurangi Margin: Implications for Slow‐Slip Events

Tisato,

Bland,

Van Avendonk

et al. 2024

Geophysical Research Letters

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“…Their mechanical behavior depends on the initial porosity and consolidation state: with the same applied stress path, strongly over‐consolidated sediments fail in a brittle way, whereas normal‐consolidated sediments fail in a ductile way (Karig & Morgan, 1994). Such behaviors have been well described by the concept of critical state soil mechanics (Wood, 1990), which does not require high temperature to facilitate strain localization and promote brittle behavior (Morgan et al., 2022). Within the Ligurian accretionary complex, the red and gray scaly clays tested in this study belonged to the same fossil accretionary prism, and therefore had a similar burial, polyphasic folding deformation, late brittle deformation and exhumation history.…”

Section: Discussionmentioning

confidence: 99%

Heterogeneity‐Driven Localization and Weakening in Scaly Clays From a Fossil Accretionary Prism

Aretusini,

Mittempergher,

Remitti

et al. 2023

JGR Solid Earth

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In accretionary prisms, scaly clays structure might be the result of strain localization and weakening or strain delocalization and hardening. Therefore, it is not clear how they influence the mechanical behavior of the accretionary prism. Here, we investigate the effect of rock fabric on the mechanical properties of scaly clays sampled from a fossil accretionary prism in a range of pressure‐temperature conditions typical of burial within accretionary prisms. We performed triaxial experiments using a direct shear configuration on samples in which the natural scaly clay fabric and natural lithological boundaries were preserved, at confining pressures of 10 ‐ 120 MPa and temperatures of 25 ‐ 150 °C. Samples with homogeneous composition and natural scaly fabrics display strain hardening behavior at all tested conditions. Shearing at high P‐T displays lower strength with respect to shearing at low P‐T. The samples containing a lithological contact display strain hardening at low P‐T and weakening at high P‐T conditions. After the experiments, the homogeneous samples show a distributed foliation and short, discontinuous shear surfaces at the contacts with the sample holder, while the samples including a contact developed a through‐going shear zone composed of a series of en‐echelon shear surfaces. A reduced smectite and water content is observed in the post‐deformation samples, suggesting that weakening may correlate with water release during dehydration reactions of clay minerals at 150 °C. This shows how both dehydration reactions at high P‐T conditions and strain localization along lithological boundaries promote brittle behavior within scaly clays in subduction zones accretionary prisms.

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“…(2019) and Morgan et al. (2022), it is clear that the physical properties of the hanging wall and foot wall sides of the splay fault are different. To consider the temporal evolution of strain and stress and their relaxation process, especially on the differences in effective viscosity (bi‐ or tri‐viscoelastic material effect), viscoelasticity should be assumed (Fukahata & Matsu’ura, 2006; Sun et al., 2014).…”

Section: Introductionmentioning

confidence: 96%

“…It is also necessary to construct at least a tri‐material model to consider the interaction between plate boundaries and splay faults. Within the continental crust, including the splay fault, the physical properties are likely to be heterogeneous between hanging wall and foot wall due to deformation on geologic time scales (Conin et al., 2012; Morgan et al., 2022). Therefore, it is necessary to construct tri‐material models with different physical properties.…”

Section: Introductionmentioning

confidence: 99%

“…However, no previous studies have accurately considered for the influence of the rheological properties of bi-or tri-materials, such as subducting oceanic crust and foot wall and hanging wall of splay faults present in continental crust. As described in Fagereng et al (2019) and Morgan et al (2022), it is clear that the physical properties of the hanging wall and foot wall sides of the splay fault are different. To consider the temporal evolution of strain and stress and their relaxation process, especially on the differences in effective viscosity (bi-or tri-viscoelastic material effect), viscoelasticity should be assumed (Fukahata & Matsu'ura, 2006;Sun et al, 2014).…”

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confidence: 99%

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Strain and Stress Accumulation in Viscoelastic Splay Fault and Subducting Oceanic Crust

Muramoto

Ito

Miyakawa

et al. 2023

Geophysical Research Letters

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This study constructs a model to represent the strain–stress field surrounding a splay fault and demonstrates the accumulation processes of both strain and stress around the splay fault. We consider the case of multiple fault dislocations, construct the model as a function of the effective viscosity in the media, and investigate the influence of the effective viscosity on the strain and stress accumulation patterns. The results show that the strain and stress tend to accumulate in the splay fault and the subducting oceanic crust, and the rate of accumulation varies with the effective viscosity. The accumulation and relaxation of strain and stress are simultaneous, and the slower the effective viscosity, the slower the accumulation rate. We discuss the relationship between the splay faults, fluid, and intraslab earthquakes. Finally, the possibility that effective viscosity may contribute to the mode of occurrence of intraslab earthquakes at the Hikurangi subduction margin is discussed.

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Seafloor overthrusting causes ductile fault deformation and fault sealing along the Northern Hikurangi Margin

Cited by 10 publications

References 61 publications

Permeability and Elastic Properties of Rocks From the Northern Hikurangi Margin: Implications for Slow‐Slip Events

Permeability and Elastic Properties of Rocks From the Northern Hikurangi Margin: Implications for Slow‐Slip Events

Heterogeneity‐Driven Localization and Weakening in Scaly Clays From a Fossil Accretionary Prism

Strain and Stress Accumulation in Viscoelastic Splay Fault and Subducting Oceanic Crust

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