Deformation of antigorite serpentinite at high temperature and pressure

Chernak, L. J.; Hirth, Greg

doi:10.1016/j.epsl.2010.04.035

Cited by 129 publications

(157 citation statements)

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“…Plastic crystal deformation has been suggested as a mechanism of CPO formation, based on the results of deformation experiments in which antigorite serpentinites develop CPOs from randomly oriented antigorite (Chernak and Hirth, 2010;Hilairet et al, 2007;Katayama et al, 2009). These results imply that in nature, static antigorite serpentinization precedes shear deformation.…”

Section: Introductionmentioning

confidence: 99%

“…Crystal plastic deformation has been proposed as a deformation mechanism of antigorite (Chernak and Hirth, 2010;Hilairet et al, 2007;Katayama et al, 2009;Padrón-Navarta et al, 2012;Vogler, 1987). However, the complicated crystal structure of antigorite and highly anisotropic grain shape limits crystal plastic deformation (Auzende et al, 2006).…”

Section: Antigorite Cpo In Initial Stage Of Serpentinizationmentioning

confidence: 99%

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Antigorite crystallographic preferred orientations in serpentinites from Japan

Soda

Wenk

2014

Tectonophysics

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Foliated antigorite serpentinites are contributing to seismic anisotropy in subduction zones. However, uncertainty remains regarding the development of antigorite crystal preferred orientations (CPO). This study analyzes the CPOs of antigorite and olivine in variably serpentinized samples of antigorite serpentinite from three localities in Southwest Japan, using U-stage, EBSD, and synchrotron X-rays. In all samples (010) poles show a maximum parallel to the lineation, and (001) poles concentrate normal to the foliation with a partial girdle about the lineation. (100) poles are less distinct and scatter widely. The three measurement methods give similar results, though orientation distributions from X-ray analysis which averages over larger sample volumes are more regular and weaker than U-stage and EBSD which focuses on local well-crystallized grains. In olivine-bearing serpentinite, the olivine CPO does not appear to control the antigorite CPO, though there are some topotactic relationships. The antigorite CPO formed contemporaneously with serpentinization and shear deformation. Based on our analyses, in a subduction zone mantle wedge, the (010) pole of antigorite is parallel to the direction of the subduction, and (001) lattice planes are parallel to the interface of the subducting oceanic plate. By averaging single crystal elastic properties over orientation distributions wave velocities have been calculated. Fast P velocities are parallel to the subduction direction and slow velocities are perpendicular to the subducting plate with an anisotropy of 10-15%.

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Section: Introductionmentioning

confidence: 99%

Section: Antigorite Cpo In Initial Stage Of Serpentinizationmentioning

confidence: 99%

Antigorite crystallographic preferred orientations in serpentinites from Japan

Soda

Wenk

2014

Tectonophysics

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“…Antigorite deformation at low temperature (LT) is controlled by the anisotropy of the crystal structure, with dislocation glide along the antigorite (001) basal plane being a very effective deformation mechanism. The von Mises criterion, which states that five independent slip systems are required to accommodate homogenous flow of a polycrystalline material, however, has been proposed to limit the accommodation of strain by dislocation glide of antigorite (Chernak and Hirth, 2010;Hirth and Guillot, 2013). Deformation experiments on antigorite serpentinites by Hilairet et al (2007) and Chernak and Hirth (2010) (100), (010) and (001) assuming a strain rate of 10 −14 s −1 and 50 MPa for a strain rate of 10 −10 s −1 .…”

Section: Deformation Processes and Conditions Recorded By The Mylonitmentioning

confidence: 99%

“…The von Mises criterion, which states that five independent slip systems are required to accommodate homogenous flow of a polycrystalline material, however, has been proposed to limit the accommodation of strain by dislocation glide of antigorite (Chernak and Hirth, 2010;Hirth and Guillot, 2013). Deformation experiments on antigorite serpentinites by Hilairet et al (2007) and Chernak and Hirth (2010) (100), (010) and (001) assuming a strain rate of 10 −14 s −1 and 50 MPa for a strain rate of 10 −10 s −1 . Chernak and Hirth (2010) report on semibrittle deformation with contributions of crystal-plastic deformation, and their findings likewise show a low strength of antigorite aggregates.…”

Section: Deformation Processes and Conditions Recorded By The Mylonitmentioning

confidence: 99%

“…Avé Lallemant, 1978;Ingrin et al, 1992;Orzol et al, 2006;Zhang et al, 2006;Zhang and Green, 2007;Moghadam et al, 2010; antigorite: e.g. Hilairet et al, 2007;Chernak and Hirth, 2010) microfabrics can yield information on the deformation mechanisms, as well as the stress and strain-rate conditions during burial and exhumation (e.g. Skrotzki et al, 1990;van der Wal, 1993;Altenberger, 1995;Jin et al 1998;Zhang et al, 2000;Jung and Karato, 2001;Piepenbreier and Stöckhert, 2001;Stöckhert, 2002;Andreani et al, 2005;Auzende et al, 2006;Jung et al, 2006;Wassmann et al, 2011;Matysiak and Trepmann, 2012).…”

Section: Introductionmentioning

confidence: 99%

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The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

Bial

Trepmann

2013

Solid Earth

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Abstract. We present microfabrics in high-pressure, metamorphic, partly serpentinized peridotite mylonites from the Voltri Massif, in which porphyroclasts and matrix record independent deformation events. The microfabrics are analysed using polarization microscopy and electron microscopy (SEM/EBSD, EMP). The mylonites contain diopside and olivine porphyroclasts originating from the mantle protolith embedded in a fine-grained matrix consisting mainly of antigorite and minor olivine and pyroxene. The porphyroclasts record brittle and crystal-plastic deformation of the peridotite at upper-mantle conditions and differential stresses of a few hundred MPa. After the peridotites became serpentinized, deformation occurred mainly by dissolutionprecipitation creep resulting in a pronounced foliation of the antigorite matrix, crenulation cleavages and newly precipitated olivine and pyroxene from the pore fluid at sites of dilation, i.e. in strain shadows next to porphyroclasts and folded fine-grained antigorite layers. Antigorite reveals a pronounced associated shape preferred orientation (SPO) and crystallographic preferred orientation (CPO) with the basal (001) cleavage plane oriented in the foliation plane. In monomineralic antigorite aggregates at sites of stress concentration around porphyroclasts, a characteristically reduced grain size and deflecting CPO as well as sutured grain boundaries indicate also some contribution of crystal-plastic deformation and grain-boundary migration of antigorite. In contrast, the absence of any intragranular deformation features in newly precipitated olivine in strain shadows reveals that stresses were not sufficiently high to allow for significant dislocation creep of olivine at conditions at which antigorite is stable. The porphyroclast microstructures are not associated with the microstructures of the mylonitic matrix, but are inherited from an independent earlier deformation. The porphyroclasts record a high-stress deformation of the peridotite with dislocation creep of olivine in the upper mantle probably related to rifting processes, whereas the serpentinite matrix records dominantly dissolution-precipitation creep and low stresses during subduction and exhumation.

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Deep long‐period earthquakes west of the volcanic arc in Oregon: Evidence of serpentine dehydration in the fore‐arc mantle wedge

Vidale

Schmidt

Malone

et al. 2014

Geophysical Research Letters

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Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40-80 km west of the volcanic arc, well above the slab, and near the Moho. These "offset DLPs" occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

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Deformation of antigorite serpentinite at high temperature and pressure

Cited by 129 publications

References 47 publications

Antigorite crystallographic preferred orientations in serpentinites from Japan

Antigorite crystallographic preferred orientations in serpentinites from Japan

The microstructural record of porphyroclasts and matrix of partly serpentinized peridotite mylonites – from brittle and crystal-plastic deformation to dissolution–precipitation creep

Deep long‐period earthquakes west of the volcanic arc in Oregon: Evidence of serpentine dehydration in the fore‐arc mantle wedge

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