title of the thesis - Department of Geology - Queen's University

2003; Taylor and Yin, 2009). These structures are currently limited to upper crustal levels (see
Fig. 2 from Styron et al., 2011 for comprehensive review).
Within the Himalaya, extensional deformation is expressed as rare strike-slip faults,
normal faults, and migmatite-cored gneiss domes, all exhibiting orogen-parallel slip directions
(Fig. 1.3; Nakata, 1989; Murphy et al., 2002, 2009; Murphy and Copeland, 2005; Thiede et al.,
2006; Jessup et al., 2008; Li and Yin, 2008, Jessup and Cottle, 2010). Gneiss domes related to
orogen-parallel extension (Fig. 1.3) are the Leo Pargil dome in the Western Himalaya (Thiede et
al., 2006), the Gurla Mandhata core complex in the central-west Himalaya (Murphy et al., 2002),
and the Ama Drime Massif in the central-east Himalaya (Jessup and Cottle, 2010 and references
therein). These domes exhume upper amphibolite to granulite facies rocks in settings that are
kinematically and contemporaneously linked to extension throughout the Himalaya and Tibetan
plateau. Note that the terms gneiss dome and core complex, used interchangeably in this study,
refer to migmatite-cored domes, and do not strictly follow the definition of Eskola (1949).
An array of mechanisms have been proposed to explain orogen-parallel deformation,
including lateral extrusion of a rigid Tibet (Tapponnier et al., 1982), oroclinal bending of the
Himalayan arc (Klootwijk et al., 1985; Ratschbacher et al., 1994; Bendick and Bilham, 2001),
gravitational instability of the Tibetan plateau (Molnar and Tapponnier, 1978; Molnar and Chen
1983; Coleman and Hodges, 1995), right-lateral oblique convergence (McCaffrey and Nabelek,
1998; Seeber and Pêcher, 1998), and radial spreading of the Tibetan plateau (England and
Houseman, 1988; Copley and McKenzie, 2007; Copley 2008; Cook and Royden, 2008). To date,
there is little consensus on which model best explains orogen-parallel extension. The kinematics
and spatial distribution of strike-slip and normal faults are commonly used to test predictions of
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