Rheological contrast between glaucophane and lawsonite in naturally deformed blueschist from Diablo Range, California. (19th November 2012)

• Record Type: Journal Article
• Authors: Kim, Daeyeong; Katayama, Ikuo; Michibayashi, Katsuyoshi; Tsujimori, Tatsuki
• Is Part Of: Island arc. Volume 22:Number 1(2013:Mar.)
• Page Start: 63
• Page End: 73
• Publication Date: 2012-11-19
• Subjects: Plate tectonics -- Periodicals; Island arcs -- Periodicals; Geodynamics -- Periodicals; 551.136
• DOI: 10.1111/iar.12003
• Languages: English
• ISSNs: 1038-4871

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Deformation microstructures for a lawsonite blueschist from the New Idria serpentinite body, Diablo Range, are investigated to clarify rheological behaviors of glaucophane and lawsonite, which are main mineral assemblages of subducting oceanic crust at relatively cold geotherm. Developments of crystal‐preferred orientations (CPOs) with small grain size, irregular grain boundary and high aspect ratio of glaucophane indicate deformation mechanism as recovery and dynamic recrystallization possibly accommodated by dislocation creep, while lawsonite deforms by rigid body rotation based on euhedral grains with angular or straight grain boundaries. Higher aspect ratios, lower angle to foliation, and stronger CPOs of both minerals in the glaucophane‐rich layer rather than those in the lawsonite‐rich layer suggest the strain localization into the glaucophane‐rich layer. Additionally fabric strength (the degree of crystal alignment) and seismic anisotropy are higher in the glaucophane‐rich layer than that of the lawsonite‐rich layer, which is consistent with the microstructural analyses. All our results imply, therefore, the dominant role of glaucophane rather than lawsonite for rheological behavior and seismic anisotropy of blueschist.</p> </abstract>