Direct evidence of water infiltration from a transform fault: Marion transform fault, Southwest Indian Ridge
Abstract
The Southwest Indian Ridge (SWIR) is one of the slowest spreading ocean ridges. Peridotites derived from the Marion transform fault along the SWIR show heterogeneous texture with coarse-grained crystals and fine-grained matrix and ultramylonitic texture, and include hydrous minerals such as amphibole, chlorite and serpentine. Olivine and spinel crystals in these peridotites have chemical compositions that indicate they are mantle origin. There are peridotites with non-deformed amphiboles and those with deformed amphiboles, which show A D-type fabrics and B-, E- and complicated fabrics of olivine, respectively. The existence of hydrous minerals indicates that peridotites were affected by water until the temperature drops down from 800 °C to <500 °C. Additionally, textures of amphiboles and olivine fabrics indicate that amphiboles were formed after deformation in the peridotites showing A D-type fabrics, on the other hand they were formed before and/or during deformation in the peridotites showing B-, E- and complicated fabrics. Therefore, it is suggested that peridotites under the transform fault are deformed under hydrous condition, consequently water infiltration to the transform fault and shear deformation under there coincidently occur.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T21D0242K
- Keywords:
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- 3902 Creep and deformation;
- MINERAL PHYSICSDE: 3621 Mantle processes;
- MINERALOGY AND PETROLOGYDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS