Tectono-magmatic evolution of the Amet granite-gneiss terrane, Sandmata Complex (NW India): Implications for Paleoproterozoic crustal accretion during Columbia assembly
Abstract
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 noncoaxial deformation. Quartz CPO patterns record WNW-ESE-directed (D 1 ) and NE-SWdirected (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.
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BibTeX
@article{sahu2026tectonomagmatic,
title = {{Tectono-magmatic evolution of the Amet granite-gneiss terrane, Sandmata Complex (NW India): Implications for Paleoproterozoic crustal accretion during Columbia assembly}},
author = {Manisha Sahu and Anwesa Banerjee and Nathan Cogné and E Mariani and N Prabhakar},
journal = {Geoscience Frontiers},
year = {2026},
month = sep,
doi = {10.1016/j.gsf.2026.102332},
url = {https://insu.hal.science/insu-05592111v2},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Tectono-magmatic evolution of the Amet granite-gneiss terrane, Sandmata Complex (NW India): Implications for Paleoproterozoic crustal accretion during Columbia assembly
AU - Manisha Sahu
AU - Anwesa Banerjee
AU - Nathan Cogné
AU - E Mariani
AU - N Prabhakar
PY - 2026
DA - 2026/09/02
JO - Geoscience Frontiers
DO - 10.1016/j.gsf.2026.102332
UR - https://insu.hal.science/insu-05592111v2
AB - 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 noncoaxial deformation. Quartz CPO patterns record WNW-ESE-directed (D 1 ) and NE-SWdirected (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.
SN - 1674-9871
ER -