U‐Pb (Zircon) Chronology of Late Paleo/Late Mesoproterozoic and Late Cambrian Tectonism in the West Garo Hills, NE India: Tracing the Eastward Continuation of a Proposed Circum‐Global Rodinia‐Age Collision Zone

Abstract The Assam‐Meghalaya Gneiss Complex (AMGC), NE India is located at the junction of a proposed present‐day E‐striking circum‐global Rodinia‐age (1.03–0.93 Ga) collision zone in the Central Indian Tectonic Zone (CITZ) and a NNE‐striking Pan African collision belt. The chronology of tectonic events in AMGC is poorly constrained, and impedes global scale correlation of crustal domains. We integrate mesoscale structures and U‐Pb zircon ages to reconstruct the tectonic evolution of the West Garo Hills crustal domain in west‐AMGC bordering Bangladesh. In this domain, late Paleoproterozoic (1.68–1.62 Ga) basement gneisses and ∼1.62 Ga with steeply dipping N/NE‐striking S1a‐S1b tectonic fabrics are intruded by post‐S1b, pre‐S2 ∼1.47 and ∼1.13 Ga granitoids. A hitherto undocumented post‐S2 phase of recumbent folding tentatively associated with extensional tectonism was overprinted by local E‐striking steeply dipping S4 shear zones. The 0.50–0.48 Ga post‐tectonic granitoids mark the last phase of plutonism in this domain. The pre‐S2 1.68–1.62 Ga anatexis in the basement gneisses is prevalent throughout the CITZ, and in the charnockite‐granitoids in drill cores in northern Bangladesh. The 1.13 Ga AMGC granitoids pre‐date the 1.03–0.93 Ga syn‐collisional granitoids in the CITZ. We infer the CITZ extends across north‐Bangladesh into AMGC, but the Pan African tectonism does not extend west of AMGC. In the West Garo Hills, 1.77–1.75 Ga granitoids are similar in age with those in northern Bangladesh and flanking the CITZ in east‐central India. However, these granitoids did not experience the 1.68–1.62 Ga anatexis in the associated basement gneisses. This suggests the CITZ comprises tectonically interleaved disparately evolved crustal blocks.