Exhumation, crustal deformation, and thermal structure of the Nepal Himalaya derived from the inversion of thermochronological and thermobarometric data and modeling of the topography

• Published in: Journal of Geophysical Research 2010-06, Vol.115 (B6), p.n/a
• Main Authors: Herman, Frédéric, Copeland, Peter, Avouac, Jean-Philippe, Bollinger, Laurent, Mahéo, Gweltaz, Le Fort, Patrick, Rai, Santaman, Foster, David, Pêcher, Arnaud, Stüwe, Kurt, Henry, Pierre
• Format: Article
• Language: English
• Subjects: Convergence; Deformation; Earth Sciences; Earth, ocean, space; Exact sciences and technology; Friction; Geological time; Geomorphology; Geophysics; Himalayas; Hydrology; inverse problems; Kinematics; Mathematical models; Mathematics; numerical modeling; Plate tectonics; Sciences of the Universe; Soil erosion; thermochronology; Thrust; Topography
• ISSN: 0148-0227; 2169-9313; 2156-2202; 2169-9356
• DOI: 10.1029/2008JB006126

Two end‐member kinematic models of crustal shortening across the Himalaya are currently debated: one assumes localized thrusting along a single major thrust fault, the Main Himalayan Thrust (MHT) with nonuniform underplating due to duplexing, and the other advocates for out‐of‐sequence (OOS) thrusting in addition to thrusting along the MHT and underplating. We assess these two models based on the modeling of thermochronological, thermometric, and thermobarometric data from the central Nepal Himalaya. We complement a data set compiled from the literature with 114 40Ar/39Ar, 10 apatite fission track, and 5 zircon (U‐Th)/He thermochronological data. The data are predicted using a thermokinematic model (PECUBE), and the model parameters are constrained using an inverse approach based on the Neighborhood Algorithm. The model parameters include geometric characteristics as well as overthrusting rates, radiogenic heat production in the High Himalayan Crystalline (HHC) sequence, the age of initiation of the duplex or of out‐of‐sequence thrusting. Both models can provide a satisfactory fit to the inverted data. However, the model with out‐of‐sequence thrusting implies an unrealistic convergence rate ≥30 mm yr−1. The out‐of‐sequence thrust model can be adjusted to fit the convergence rate and the thermochronological data if the Main Central Thrust zone is assigned a constant geometry and a dip angle of about 30° and a slip rate of