A Petrographic Intimation of Early Initiation of Main Boundary Thrust (MBT) from the Late Miocene Foreland Basin Fill Sandstone, North Western Himalaya

S, Sruthi P. (2015) A Petrographic Intimation of Early Initiation of Main Boundary Thrust (MBT) from the Late Miocene Foreland Basin Fill Sandstone, North Western Himalaya. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Sruthi P.S (10MS73)) Sruthi_P.S-MS_DissertationReport-2015.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

Himalayan Fold Thrust Belt, a classical example of continent – continent collision, has suffered numerous thrusting activity during the mountain building processes. Among these the Main Central Thrust (MCT) and Main Boundary Thrust (MBT) attracted more attention for past few decades because of their large lateral displacement. While the initiation of MCT has been well documented across the entire Himalayan arc, such detailed knowledge is still lacking for the MBT. To have a better understanding on activation of the MBT in North Western Himalaya, Late Miocene sandstone petrography has been carried out on Ranital and Nalad Khad section from Kangra sub basin, Himachal Pradesh, India. The assumption behind the present work is that hinterland tectonic activity is synchronous with the timing of deposition of detrital grains in basin-fill sediments. The textural parameters (grain size, sorting and roundness) coupled with paleo-current data shows that Nalad Khad is much closer to the source region than Ranital. Petrography of sandstone samples collected from Ranital and Nalad Khad section indicates a marked rise in modal percentage of sedimentary rock fragments (SRF) during ~9 Ma and ~10.7 Ma respectively. Exhumation along the MBT would have exposed the Lesser Himalayan rocks comprising of sedimentary and low grade metamorphic rocks resulted in an increase supply of SRF in the foreland basin. Since Nalad Khad is closer to the source region, the effect of MBT initiation is much earlier here than Ranital. The modal percentage of basin fill sandstone indicates that the MBT was initiated at least by ~10.7 Ma ago.

Actions (login required)

View Item