Tectono-magmatic evolution of the Amet granite-gneiss terrane, Sandmata Complex (NW India): Implications for Paleoproterozoic crustal accretion during Columbia assembly

• Gneisses (D 1 –D 4 ) and granitoids (D 1 –D 3 ) in the Amet region record multiphase deformation. • EBSD analyses of granitoids reveal a shift from monoclinic (S 1 ) to triclinic (S 2 –S 3 ) shear regimes. • Zircon dating indicates crystallization of Amet pluton at ∼ 1823 Ma. • Monazite dating constrain timing of S 1 at ∼ 1670 Ma and S 2 –S 3 at ∼949 Ma in the granitoids. • Extensive ∼1.8–1.7 Ga granitoid magmatism in the Sandmata Complex during Columbia assembly. The Sandmata Complex in the Aravalli orogen (NW India) preserves an extensive Paleoproterozoic geological record characterized by granulite-facies metamorphism, granitoid magmatism, and multiphase deformation. This study integrates structural, petrological, geochemical, and geochronological data to reconstruct the tectonomagmatic evolution of garnet-bearing granitoids and metamorphic history of the host gneisses in the Amet region. The gneisses record four deformation events (D 1 –D 4 ), whereas the granitoids preserve three deformation phases (D 1 –D 3 ). The D 2 –D 4 in gneisses correspond temporally D 1 –D 3 in the granitoids. Crystallographic preferred orientation (CPO) analyses of granitoids reveal a transition from monoclinic (S 1 ) to triclinic shear regimes (S 2 -S 3 ), indicating progressive non-coaxial deformation. Quartz CPO patterns record WNW–ESE-directed (D 1 ) and NE–SW-directed (D 2 -D 3 ) brittle-viscous shearing accompanied by dynamic recrystallization at 500–600 °C. The gneisses record syn -D 2 peak metamorphic conditions of 5.8–6.6 kbar, 660–680 °C. The Amet granitoids crystallized at 6.0–7.4 kbar, 730–775 °C, and contain inherited garnet cores (Grt-I) with peritectic rims (Grt-I rim) and matrix garnets (Grt-II). REE patterns and negative Eu anomalies in the pre-D 1 garnets indicate a two-stage growth history related to evolving melt composition and P–T conditions. U–Pb zircon dating constrains granitoid crystallization at ∼1823 Ma. In-situ monazite geochronology records deformation events at ∼1670 Ma (D 1 ) and ∼949 Ma (D 2 –D 3 ), the latter representing an imprint of the Delhi Orogeny. These results indicate partial melting and magma emplacement, driven by long-lived subduction during the Aravalli orogeny. The findings of this study provide robust evidence of Paleoproterozoic magmatism and continent-scale collisions during ∼2.1–1.8 Ga, highlighting the significance of Aravalli orogen in the assembly of the Columbia supercontinent.