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Semi-brittle behavior of wet olivine aggregates: the role of aqueous fluid in faulting at upper mantle pressures
- Source :
- Contributions to Mineralogy and Petrology. 173
- Publication Year :
- 2018
- Publisher :
- Springer Science and Business Media LLC, 2018.
-
Abstract
- The role of aqueous fluid in fracturing in subducting slabs was investigated through a series of deformation experiments on dunite that was undersaturated (i.e., fluid-free) or saturated with water (i.e., aqueous-fluid bearing) at pressures of 1.0–1.8 GPa and temperatures of 670–1250 K, corresponding to the conditions of the shallower regions of the double seismic zone in slabs. In situ X-ray diffraction, radiography, and acoustic emissions (AEs) monitoring demonstrated that semi-brittle flow associated with AEs was dominant and the creep/failure strength of dunite was insensitive to the dissolved water content in olivine. In contrast, aqueous fluid drastically decreased the creep/failure strength of dunite (up to ~ 1 GPa of weakening) over a wide range of temperatures in the semi-brittle regime. Weakening of the dunite by the aqueous fluid resulted in the reduction of the number of AE events (i.e., suppression of microcracking) and shortening of time to failure. The AE hypocenters were located at the margin of the deforming sample while the interior of the faulted sample was aseismic (i.e., aseismic semi-brittle flow) under water-saturated conditions. A faulting (slip rate of ~ 10−3 to 10−4 s−1) associated with a large drop of stress (Δσ ~ 0.5 to 1 GPa) and/or pressure (ΔP ~ 0.5 GPa) was dominant in fluid-free dunite, while a slow faulting (slip rate
- Subjects :
- Pressure drop
geography
geography.geographical_feature_category
Olivine
010504 meteorology & atmospheric sciences
Drop (liquid)
Slip (materials science)
Fault (geology)
engineering.material
010502 geochemistry & geophysics
01 natural sciences
Geophysics
Brittleness
Creep
Acoustic emission
Geochemistry and Petrology
engineering
Petrology
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 14320967 and 00107999
- Volume :
- 173
- Database :
- OpenAIRE
- Journal :
- Contributions to Mineralogy and Petrology
- Accession number :
- edsair.doi...........029337e64013f4e86544ed82183b4890