HR: 1340h
AN: T43A-1382    [Abstracts]
TI: Effective Elastic Thickness Of The India Plate From Receiver Function Imaging, Gravity Anomaly And Numerical Modelling
AU: * Hetenyi, G
EM: hetenyi@clipper.ens.fr
AF: Laboratoire de Geologie, Ecole Normale Superieure, 24, rue Lhomond, Paris, 75005 France
AU: Cattin, R
EM: cattin@geologie.ens.fr
AF: Laboratoire de Geologie, Ecole Normale Superieure, 24, rue Lhomond, Paris, 75005 France
AU: Vergne, J
EM: vergne@geologie.ens.fr
AF: Laboratoire de Geologie, Ecole Normale Superieure, 24, rue Lhomond, Paris, 75005 France
AU: Nábělek, J
EM: nabelek@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331 United States
AB: The rheology of the lithosphere has been subject to controversy since several years. This is mainly due to the difficulty to determine accurately the effective elastic thickness (EET), which depends on the decoupling within the lithosphere. In the flexural basin of the Himalayan foreland, current estimates give an EET from 36 km up to 80 km. This wide range is mainly due to the lack of geometrical constraints on the flexure of the India plate. The aim of this work is to assess the EET using thermo-mechanical modelling and the geometry of the main lithospheric structures imaged from the Hi-CLIMB experiment.
The geometry of the Ganges basin is obtained by the method of receiver functions adapted for subsurface structures. The analysis of synthetic waveforms and non-linear inversions show 5 km of sediments overlying a 35 km thick crust, both very gently dipping (1°).
Receivers functions, obtained by the analysis of telesesimic signals recorded at all the Hi-CLIMB stations on the main profile, are also used to isolate direct and multiple conversions from the Moho. It enables us to obtain a continuous and accurate geometry of the Moho from the Ganges basin up to central Tibet. Associated to pre-existing geophysical data, including deep well and gravity data, this dataset enables us to better constrain the 2-D model.
Numerical modelling with three layers and various rheologies give a high EET under the Indian continent (>60-70 km), which abruptly drops to 30-40 km in the Ganges basin 200 km south of the MFT. These results suggest a coupled Indian lithosphere in agreement with "jelly-sandwich" rheology.
DE: 1236 Rheology of the lithosphere and mantle (7218, 8160)
DE: 7218 Lithosphere (1236)
DE: 8160 Rheology: general (1236, 8032)
DE: 9320 Asia
SC: Tectonophysics [T]
MN: Fall Meeting 2005