What Formed the Basement Ridges on the Indian Plate?

Friday, 19 December 2014
Jolante W Van Wijk1, Michael Murphy2, An Yin3, Nicole Arres4 and Rediet Abera1, (1)New Mexico Institute of Mining and Technology, Socorro, NM, United States, (2)University of Houston, Houston, TX, United States, (3)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (4)Southwestern Energy Company, Houston, TX, United States
It has long been known that five basement ridges (highs) are located on the northern Indian Plate in the Himalayan Foreland Basin. The ridges (from west to east Delhi-Lahore-Sargodha, Delhi-Hardwar, Manghyr-Saharsa, Faizabad and Rajmahal-Garo) are oriented more or less perpendicular to the Main Boundary thrust, and their crests are several hundreds of kilometers apart. They separate deeper sub-basins of the foreland system. Goal of this study is to understand the origin of the basement highs.

The Himalayan Foreland Basin can well be explained by flexural deformation as a result of the load of the Himalayas and the infill of the foreland basin. One possible explanation for the basement highs and lows is differential loading of the subducted part of the plate. We used the geometry of the foreland basin and the load to estimate the effective elastic thickness of the northern Indian Plate with 3D flexural models, and included lateral variations in the load. The basement ridges could, however, not be reproduced. Buckling of the Indian Plate did, however, reproduce the observed highs and lows of the Indian Plate. There are several possible causes for buckling of the northern Indian Plate including compression and loading of the edges of the Indian Plate by the sediment load of the Ganges and Indus deltas.