Experimental Faulting of Serpentinite during Dehydration: Implications for Earthquakes, Seismic Low-Velocity Zones, and Anomalous Hypocenter Distributions in Subduction Zones

Jung, Haemyeong; Green, Harry W.

doi:10.2747/0020-6814.46.12.1089

Cited by 48 publications

(22 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Serpentine can start to influence fault mechanics from the onset of peridotite hydration, when only a small amount of serpentine (10-15% of total rock volume) can lead to a significant weakening effect (e.g., [48]). Conversely, serpentine dehydration and breakdown to anhydrous and relatively strong minerals has been linked to fluid overpressure, embrittlement and intermediate-depth seismicity in subduction zones (e.g., [7,9,10]). A key mechanical feature of serpentinites that has been highlighted in recent review articles (e.g., [11,12,14]), is that they are relatively weak under certain P-T conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Due to their unique physical and rheological properties, serpentinites play a fundamental role in a wide range of geodynamic processes, ranging from fault zone weakening and aseismic creep along major fault zones at shallow depths (e.g., [1][2][3][4][5][6]) to high-temperature dehydration embrittlement and seismogenesis in subduction zones (e.g., [7][8][9][10]). Several recent papers have provided thorough reviews of the mechanical properties, deformation mechanisms and tectonic significance of serpentinite (e.g., [11][12][13][14]).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

et al. 2018

View full text Add to dashboard Cite

Serpentinites play a key role in controlling fault rheology in a wide range of geodynamic settings, from oceanic and continental rift zones to subduction zones. In this paper, we provide a summary of the most common deformation mechanisms and frictional strengths of serpentine minerals and serpentinites. We focus on deformation mechanisms in retrograde serpentinites, which show a progressive evolution from undeformed mesh and bastite pseudomorphic textures to foliated, ribbon-like textures formed by lizardite with strong crystallographic and shape preferred orientations. We also discuss the possible mechanical significance of anastomosing slickenfibre veins containing ultraweak fibrous serpentines or relatively strong splintery antigorite. Our review and new observations indicate that pressure solution and frictional sliding are the most important deformation mechanisms in retrograde serpentinite, and that they are frictionally weak (µ~0.3). The mineralogical and microstructural evolution of retrograde serpentinites during shearing suggests that a further reduction of the friction coefficient to µ of 0.15 or less may occur during deformation, resulting in a sort of continuous feedback weakening mechanism.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

et al. 2018

View full text Add to dashboard Cite

show abstract

“…These studies also demonstrate that lizardite, chrysotile, and assemblages of serpentine minerals are much weaker than antigorite. Brittle behavior is also observed in antigorite above these pressures when temperature is increased, associated with the “dehydration‐embrittlement” phenomenon (Jung & Green, ; Raleigh & Paterson, ). However, recent deformation experiments show that brittle behavior is also widely observed across the antigorite stability field even at elevated pressures and temperatures (Chernak & Hirth, ; Gasc et al, ; Proctor & Hirth, ).…”

Section: Introductionmentioning

confidence: 99%

Absence of Stress‐Induced Anisotropy During Brittle Deformation in Antigorite Serpentinite

et al. 2018

View full text Add to dashboard Cite

Knowledge of the seismological signature of serpentinites during deformation is fundamental for interpreting seismic observations in subduction zones, but this has yet to be experimentally constrained. We measured compressional and shear wave velocities during brittle deformation in polycrystalline antigorite, at room temperature and varying confining pressures up to 150 MPa. Ultrasonic velocity measurements, at varying directions to the compression axis, were combined with mechanical measurements of axial and volumetric strain, during direct loading and cyclic loading triaxial deformation tests. An additional deformation experiment was conducted on a specimen of Westerly granite for comparison. At all confining pressures, brittle deformation in antigorite is associated with a spectacular absence of stress‐induced anisotropy and with no noticeable dependence of wave velocities on axial compressive stress, prior to rock failure. The strength of antigorite samples is comparable to that of granite, but the mechanical behavior is elastic up to high stress ( ≳80% of rock strength) and nondilatant. Microcracking is only observed in antigorite specimens taken to failure and not in those loaded even at 90–95% of their compressive strength. Microcrack damage is extremely localized near the fault and consists of shear microcracks that form exclusively along the cleavage plane of antigorite crystals. Our observations demonstrate that brittle deformation in antigorite occurs entirely by “mode II” shear microcracking. This is all the more remarkable than the preexisting microcrack population in antigorite, is comparable to that in granite. The mechanical behavior and seismic signature of antigorite brittle deformation thus appears to be unique within crystalline rocks.

show abstract

“…The velocity anisotropies for P waves for Malenco serpentinite (15–27%) compare fairly well with serpentinite from Hida, Japan (23–28%) [ Watanabe et al ., , ] and samples from several locations in Liaoning Province, China (13–17%) [ Ji et al ., ; Shao et al ., ]. Thus, the sample described here seems to be representative of a range of serpentinites found in subduction zones, and elastic data can be used for seismic models [e.g., Peacock and Hyndman , ; Jung and Green , ]. This report is intended to present experimental results for a classic serpentinite sample and not to elaborate on implications for mantle anisotropy.…”

Section: Discussionmentioning

confidence: 99%

Seismic anisotropy of serpentinite from Val Malenco, Italy

et al. 2015

View full text Add to dashboard Cite

Serpentinites, deformed in mantle subduction zones, are thought to contribute significantly to seismic anisotropy of the upper mantle and have therefore been of great interest with studies on deformation, preferred orientation, and elastic properties. Here we present a combined study of a classical sample from Val Malenco, Italy, investigating the microstructure and texture with state‐of‐the art synchrotron X‐ray and neutron diffraction methods and measuring ultrasonic velocities both with a multi‐anvil apparatus and a novel instrument to measure 3‐D velocities on spheres. Both, results from diffraction methods and velocity measurements are compared, discussing advantages and disadvantages. From spherical velocities, elastic tensor properties can be derived by inversion. Also from quantitative texture measurements, elastic properties can be modeled by self‐consistent averaging. Good agreement between the velocity and microstructural models is observed.

show abstract

Experimental Faulting of Serpentinite during Dehydration: Implications for Earthquakes, Seismic Low-Velocity Zones, and Anomalous Hypocenter Distributions in Subduction Zones

Cited by 48 publications

References 66 publications

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

Deformation Processes, Textural Evolution and Weakening in Retrograde Serpentinites

Absence of Stress‐Induced Anisotropy During Brittle Deformation in Antigorite Serpentinite

Seismic anisotropy of serpentinite from Val Malenco, Italy

Contact Info

Product

Resources

About