Publication Date
Summer 2024
Abstract
The South Tibetan Detachment System (STDs) is a north-dipping, shear zone that played a major role in the evolution of the Himalayan orogeny. Despite this, its true nature is not completely understood as it is yet to be determined as purely a system of low-angle normal faulting or rather passive roof thrusting in which both extensional and contractional deformation takes place. The Channel flow Model views the role and timing of the STDs as coinciding with the Main Central Thrust (MCT) to squeeze out/extrude the lower crust of Tibet. In this model, due to the over-thickening of the Tibetan crust, the MCT and STDs squeeze out this portion due to a pressure gradient. The deformational features expected to see are those purely extensional indicative of only normal faulting of the STDs of top to the North. Alternatively, the Passive Roof Thrust model indicates that the Tethyan Sequence as a roof thrust to a thrust duplex within the Greater Himalayas. For this model to be supported, the STDs would still be moving top to the North but rather than just recording extensional deformation, both normal and thrust features would be present within the same section. This project presents evidence of both extension and contraction within the STDs and the Annpurna Yellow Band in the Kali Gandaki in alignment with the Passive Roof Thrust Model. The presence of a thrust duplex within the greater Himalayan crystallines implies a significant amount of shortening that is not accounted for in calculations of crustal shortening absorbed in the Himalayan thrust belt.
Disciplines
Life Sciences | Physical Sciences and Mathematics
Recommended Citation
Sloat, Cate, "Structural Analysis of the South-Tibetan Detachment Assessing Channel Flow Model and Passive Roof Thrust Model" (2024). Nepal: Geoscience in the Himalaya. 2.
https://digitalcollections.sit.edu/npg/2