Dynamics of Early Neoproterozoic accretion, west-central India: II ~1.65 Ga HT-LP and ~0.95 Ga LT-HP metamorphism in Godhra-Chhota Udepur, and a tectonic model for Early Neoproterozoic accretion

The N/NNE-striking Aravalli Delhi Fold Belt (ADFB) and the E-striking Central Indian Tectonic Zone (CITZ) converge at Godhra-Chhota Udepur (GC) sector, west-central India. Analyses of mesoscale deformation structures metamorphic phase equilibria in basement supracrustal rocks are integrated with geochronological-geochemical data (accompanying article) to address dynamics Early Neoproterozoic CITZ-ADFB accretion. In GC ~1.65 Ga granulite facies anatectic gneisses, ~2.5 1.03–1.02 granitoids, greenschist amphibolite allochthonous constitute a tectonic mélange (D2 deformation). lithodemic units traversed by networks W/WNW-striking steep-dipping transpressional shear zones sinistral kinematics (D3). shallow-dipping top-to-the south is intruded post-D2 syn-D3 0.95–0.93 granitoids. Mn-NCKFMASH P-T pseudosection analyses gneisses pre-D2 garnet + cordierite-bearing leucosomes suggest evolved along clockwise path range 5–6 kbar 680–720 °C. By contrast, (0.95–0.93 Ga) chlorite phengite (Si up 3.32 apfu) clinozoisite quartz ± biotite schists attained pre/syn-D2 peak conditions (10–12 kbar, 450–500 °C). NCKFMASH ~0.95 phengite-bearing indicate high-P, low-T path; phengite-poor micas defining D3 fabric 3.04 attest post-peak decompression schists. ADFB granites accreted HT-LP ~1.03 granites, LT-HP CITZ during D2 thrusting. crustal convergence continued emplacement granitoids that culminated nucleation zones. This broad contemporaneity among felsic plutonism, metamorphism rocks, D2-D3 shortening interpreted be result switch subduction polarity between 1.03 0.93 oblique ADFB-CITZ convergence.