71 The Geodynamic Evolution of the Himalaya: From Mountain Building to Modern Seismicity and Climate Change (Posters)

The Himalaya are an active mountain chain whose geology affects people in more than six Asian countries. This interdisciplinary session focuses on the geodynamics of the region as well as the impact of modern seismicity and climate change

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Structure and Kinematic Evolution of the Naga Fold-Thrust Belt, Northeast India

Paper number: 71-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The easternmost terminus of the Himalayan orogen is defined by a continental triple junction between the Indian, Eurasian, and Burman plates. The Naga fold-thrust belt (NFTB) represents the SW arm of this triple junction and accommodates convergence between the Burma plate and the trailing edge of the Indian plate. Previous studies disagree on the kinematic evolution of the NFTB, interpreting it as either a dextral shear zone or a strain-partitioned orogenic wedge. This study attempts to resolve these discrepancies through field-based structural analyses and construction of balanced cross-sections to constrain the structural evolution of the FTB and test competing hypotheses for the kinematic evolution of the triple junction. We collected structural data along three ~40 km transects mapped perpendicular to the strike of the fault-cored anticlines in the NFTB.  The stratigraphy of the NFTB includes the Mio-Pliocene syn-orogenic Namsang Formation, the Miocene-Pliocene fluvial Tipam Group, the Miocene shallow marine Surma Group, the Eocene-Miocene shallow marine and deltaic Barail Group, and the Eocene shallow marine Disang Group. Preliminary results identify the frontal thrust (Naga thrust) as a blind thrust that folds the Tipam Formation. A second thrust splay places the Barail Group above the Tipam Group ~20 km southeast of the Naga thrust. A third thrust splay, ~15 km southeast, imbricates the Barail–Tipam section again. The southern transect contains an additional duplex-related thrust that is not present in the central or northern transects.  The frontal thrusts are cross-cut by an out-of-sequence thrust (Disang Thrust) that juxtaposes the Disang Group above the Barail Group in the internal part of the wedge. In the hanging wall of the Disang thrust, the Disang-Barail contact is folded into regional anticlines and synclines and thickened by imbricated intraformational thrusts. The central and northern transects contain outcrop-scale folds and faults within the shale of the Disang Group. Preliminary results reveal a series of thrusts and fault-cored anticlines that propagated northwestward to accommodate margin-normal convergence, no evidence for significant strike-slip faulting was observed in the study area. Our results provide evidence for strain partitioning in the NFTB and constrain the kinematic evolution of the India–Burma–Eurasia triple junction.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413005

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.