B-type olivine fabric induced by grain boundary sliding - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Earth and Planetary Science Letters Year : 2014

B-type olivine fabric induced by grain boundary sliding

Abstract

Mineral Lattice Preferred Orientation (LPO) in naturally deformed peridotite is typically interpreted to result from the motion of intra-crystalline dislocations during dislocation creep. The degree of mineral alignment (fabric strength) is often assumed to increase with increasing finite strain. Here, we document olivine LPOs in peridotites in a kilometer-scale mantle shear zone in the Ronda massif (Spain) that demonstrate a transition from a flow-parallel [100]-axis LPO (A-type fabric) to a flow-normal [100]-axis LPO (B-type fabric). We conclude that the B-type fabric in the Ronda peridotite results from the enhancement of grain boundary sliding (GBS) with decreasing grain size, rather than a change in the dominant dislocation slip system because: (1) dislocation sub-structures remain consistent with the A-type slip system in all samples; (2) the fabric transition correlates with decreasing fabric strength despite increasing finite strain; (3) the analysis of deformation conditions in Ronda is inconsistent with the experimental conditions, including water content, inferred to promote the dominance of (010)[001](010)[001] slip in laboratory samples, and (4) our observations are supported by experiments that document B-type fabric in olivine aggregates where deformation involves a component of GBS. Our results have important implications for interpreting the rheological properties of shear zones and upper mantle structures via micro-structural and seismic observations.
Fichier principal
Vignette du fichier
Precigout_Hirth_EPSL.pdf (1.99 Mo) Télécharger le fichier
Vignette du fichier
Figures_EPSL.jpg (71.87 Ko) Télécharger le fichier
Origin Files produced by the author(s)
Format Figure, Image
Loading...

Dates and versions

insu-00985098 , version 1 (29-04-2014)

Identifiers

Cite

Jacques Précigout, Greg Hirth. B-type olivine fabric induced by grain boundary sliding. Earth and Planetary Science Letters, 2014, 395, pp.231-240. ⟨10.1016/j.epsl.2014.03.052⟩. ⟨insu-00985098⟩
400 View
346 Download

Altmetric

Share

Gmail Mastodon Facebook X LinkedIn More