Document Type

Thesis

Date of Degree Completion

Spring 2015

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Dr. Jeffrey Lee

Second Committee Member

Dr. Chris Mattinson

Third Committee Member

Dr. Anne Egger

Abstract

The Zanskar normal fault (ZF) is a NW-striking, moderately NE-dipping, normal fault that bounds the northern flank of the Greater Himalaya Range, NW India. The ZF is the far west continuation of the South Tibetan Detachment System (STDS), a major arc-parallel normal sense shear zone that spans the length of the Himalayan orogen. Detailed new zircon and apatite (U-Th)/He (ZHe and AHe) and apatite fission-track (AFT) thermochronometric data from high-grade (amphibolite-migmatite) Greater Himalayan Sequence (GHS) metamorphic rocks, exposed in the footwall immediately adjacent to the ZF, provide constraints on the middle Miocene to present exhumation history of the footwall. The overlap of these elevation invariant mean ZHe, AFT, and AHe thermochronometric ages, indicate rapid cooling between ~14-10 Ma. Inverse modeling of ZHe, AHe, and AFT thermochronometric data yield patterns that suggest: (1) a pulse of rapid normal slip along the ZF at ~14-13 Ma and rapid exhumation of the footwall between ~14-10 Ma at rates of 0.2-2.5 mm/yr, and (2) slow exhumation and/or quiescence between ~9 Ma to the present day. We suggest that the period of rapid normal slip along the ZF can be best explained by southward extrusion of the GHS by a modified channel flow mechanism and/or by an increase in gravitational potential energy as a consequence of a slab break-off event.

Available for download on Tuesday, August 25, 2020

Share

COinS