Progressive deformation partitioning and recrystallization of olivine in the lithospheric mantle

摘要: Abstract Intense serpentinization within the Machinoyama ultramafic body, eastern-most part of Yakuno ophiolite in Paleozoic Maizuru belt, SW Japan, resulted development block-in-matrix structure brittle regime, possibly associated with exhumation along a fault. Various microstructures are heterogeneously distributed throughout peridotite blocks serpentinite matrix. The classified into four domains according to olivine grain size: coarse (1.0–1.5 mm), medium (0.5–1.0 mm), small (0.2–0.5 mm), and fine-grained (0.01 mm). Even single block, medium-, small- occur at various scales. In particular, domain occurs thin zones that cut across other domains. These observations suggest deformation peridotites before was partitioned anastomosing during progressive inhomogeneous non-coaxial shear, resulting simultaneous range from coarse-grained small-grained domain. Olivine crystal-preferred orientations tend be weaker decreasing size, indicating change mechanism dislocation creep grain-size-sensitive creep. Moreover, contain much more second phase than even same sample, suggesting role phases on strain localization dynamic recrystallization olivine.