The bedding shear structures of the Lhasa Riduo basin in the late Jurassic-early Cretaceous, and it’s geological significances

Located in southern Gangdise volcanic arc, the late Jurassic-early Cretaceous Lhasa-Riduo basin, Tibet, experienced two deformation stages under different tectonic settings. Based on detailed geological investigation, the bedding shear structures such as bedding recumbent folds, bedding foliations, stretching lineations, viscous boudinages and syntectonic leucocratic veins are recognized in this paper. Studies on microstructural deformation and EBSD analyses indicate that deformations of quartzs in bedding shear zones were currently dominated by basal glides and rhombohedral glides,with the mid-low temperature(400℃~500℃)fabrics, but previously, they experienced deformation stages of the medium-high temperature fabric (550℃~650℃) prismatic glide and the late low-temperature fabric (<400℃) basal glide .The authors suggest a possible model for the bedding shear structures in the Lhasa-Riduo Basin. It is believed that the bedding shear structures in the Lhasa-Riduo basin were formed by a large-scale horizontal and stratified shear action which was under the extensional tectonic setting during the Late Jurassic to the Early Cretaceous.