Geochemical constraints on the origin of ophiolitic chert from Naga Hills Ophiolite, Northeast India

The uppermost part of the Naga Hills ophiolite (NHO) sequence representing vestiges of the Neo-Tethyan ocean in the Indo-Myanmar ranges, consists of Late Jurassic to Late Cretaceous cherts that carapace the ophiolitic volcanics.This contribution presents petrographic and whole rock geochemical studies to comprehend their origin and paleo-depositional environment.The occurrences of abundant radiolarian microfossils in the studied cherts are observed.Geochemical signatures of these cherts indicate that they are generated at rifted arc basin by pronounced hydrothermal activity along with terrigenous material influx from active continental margin.Redox sensitive trace element proxies U/Th (0.12-0.74),Ni/Co (0.10-0.67) and V/(V+Ni) (0.22-0.47) record oxic paleo-redox conditions of formation.The cherts of NHO are envisaged to have formed in a transitional tectonic environment associated with magmatism and subsequent sedimentation in a rifted arc basin proximal to an active continental margin.