Document Type

Thesis

Date of Degree Completion

Fall 2014

Degree Name

Master of Science (MS)

Department

Geological Sciences

Committee Chair

Jeff Lee

Second Committee Member

Christopher Mattinson

Third Committee Member

Audrey Huerta

Abstract

New kinematic, microtextural, and thermochronology studies test the hypothesis that high temperature-moderate pressure rocks exposed in Gianbul Dome, NW India, were exhumed south of the southern Tibetan detachment system by the southward extrusion of a mid-crustal ductile channel. Mesoscopic and microscopic kinematic indicators record normal-sense shear in the Khanjar and Zanskar shear zones, which define the southwest and northeast flanks of Gianbul Dome, respectively. Microtextural analyses indicate deformation at >400°C along dome flanks increasing to > 700°C in the core. Moderate temperature cooling is asymmetric across the dome, initiating at ~22 Ma on the southwest flank of the dome-and at ~20 Ma on the northeast flank. These data indicate that the Gianbul Dome morphology formed under ductile conditions and post­peak metamorphism and was partially exhumed initially by both the Zanskar and Khanjar shear zones. The dome then cooled and was brittlely exhumed and tilted SW in the footwall of the Zanskar normal fault. These data are broadly consistent with: l) the predictions of the channel flow model extrusion mechanism, and 2) an isostatic uplift model of ductile doming in response to upper crustal extension and resulting vertical pressure gradients.

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