Microfabric Investigations of Peridotite Xenoliths From Edmonson Point, Northern Victoria Land, Antarctica

This study examines the deformation microstructures and olivine crystallographic preferred orientations (CPOs) of spinel peridotite xenoliths from Edmonson Point, northern Victoria Land, Antarctica. By integrating petrography, mineral chemistry, and electron backscatter diffraction (EBSD)‐based CPO analysis, we aim to reconstruct mantle deformation processes and the tectonic evolution beneath the Transantarctic Mountains (TAM). The peridotite xenoliths, classified as lherzolite and harzburgites, display both A‐ and D‐type olivine fabrics, moderate to strong CPOs intensities, and equilibrium temperatures ranging from ∼835°C to 906°C. Textural evidences, fabric strength indices, and slip system characteristics suggest deformation by dislocation creep, influenced by syn‐kinematic melt percolation and subsequent recovery processes. The occurrence of D‐type olivine fabric, associated with low‐temperature and high‐stress conditions, is interpreted as a relic of early Paleozoic subduction during the Ross Orogeny. In contrast, A‐type olivine fabric reflects deformation under high‐temperature, low‐stress conditions. The wide range in partial melting degrees, inferred from spinel Cr# and olivine Fo# compositions, highlights significant structural heterogeneity and a polyphase history of the lithospheric mantle. These results provide valuable constraints on the geodynamic evolution shaping the TAM.