Chinese Acad Sci, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing Synchrotron Radiat Facil, Beijing 100039, Peoples R China
; Univ Bayreuth, Bayer Geoinst, D-95440 Bayreuth, Germany
Magnesium-iron olivine in the Sixiangkou L6 chondrite contains abundant fractures induced by plastic deformation during shock metamorphism. This study reports the discovery of lamellar ringwoodite that incoherently nucleated and grew along planar and irregular fractures in olivine. Magnesium-iron interdiffusion took place between olivine matrix and crystallizing ringwoodite at high pressures and high temperatures, which resulted in higher FeO content in ringwoodite lamellae than in olivine. This suggests that a quasi-hydrostatic high pressure lasting for several minutes should have been produced in the shock veins of the meteorite. The intracrystalline transformation of olivine to ringwoodite also has implications for phase transitions in subducting lithospheric slabs because planar and irregular fractures are commonly produced in olivine that suffered plastic deformation.