Litho-stratigraphy of Cretaceous Tidding Suture Package with Ophiolite Emplacements in Eastern Arunachal Himalaya: An Analysis

Abstract

ABSTRACT The present work is focussed on litho-stratigraphic analysis of NW-SE Cretaceous Tidding suture package in Eastern Arunachal Himalaya based on detailed mapping. The Tidding suture occurrence in northern continuation of active Andaman Supra Subduction Zone (ASSZ) in between Indian-Asian plates and its lateral extensions including Tagaung belt of Burma, and as Tsangpo suture in to the Tibet is compiled. A predominant basal hornblende schist (meta-basalt) - quartzite (meta-chert) intercalation, and upper thick greywacke-argillite as turbidite with D, E, F intervals of Bouma - alternating with thin carbonaceous phyllite - occasional limestone assemblage; overall representing as Dibang Group of sediments; define the Tidding suture package. Thus, an initial volcano-nonclastic sedimentation with upper argillaceous distal turbidite along the subducting Indian plate margin is interpreted. The eastern discontinuous pillowed Tuting volcanics with arc affinity along the contact of intrusive Mishimi massif (Tertiary Trans-Himalayan plutonic belt) is considered as co-eval along with the Dibang sedimentation. The occurrence of discontinuous high temperature extrusive sub-aqueous peridotite-serpentinite slices defining as oceanic crust in successive layers of Dibang Group, and a major slab of layered Mayudia-Mafic-Ultramafic Assemblage (MMUA) with intrusive meta-gabbro as a youngest unit; are all differentiated as ophiolite emplacements. For Tidding suture package development; a late Mesozoic composite basin of western Neo-Tethys foreland sediments subjecting to reworking in a turbidity environment along the subducting Indian plate margin, an eastern magmatic arc in a back-arc set-up with oceanic crust generation similar to ASSZ, and the middle fore-arc as an accretionary prism for accumulation of sediments and small dissected oceanic crustal slices is visualized. The structurally controlled basal Dibang sediments and youngest of MMUA occurring as closed outcrops in response to Cenozoic Himalayan orogenic movements is detailed. The overall Tidding suture package is bound by Roing and Lohit Cenozoic structures towards its west and east, along the contact of Roing Gneiss (subducting Indian plate margin) and Mishimi massif (Trans-Himalayan plutonic belt) with arc magmatism.