Metamorphic evolution of the Great Slave Lake shear zone

Abstract

Characterization of the structural and petrological evolution of plate-boundary fault zones (sensu lato, including both upper crustal faults and their underlying shear zones) is central to modelling the occurrence (or absence) of plate tectonics. Observations of both active and ancient fault zones are typically interpreted in the context of the Sibson-Scholz model of fault-zone structure (Scholz, 1988;Sibson, 1977Sibson, , 1983. In this model, increases in pressure and temperature with depth induce a transition from dominantly pressuresensitive frictional failure in the upper crust to dominantly

Dating Strike‐Slip Ductile Shear Through Combined Zircon‐, Titanite‐ and Apatite U–Pb Geochronology Along the Southern Tan‐Lu Fault Zone, East China

“…Whether the documented deformation timing reflects a single protracted event, or two discrete events is important to assess to understand the history of the Fucha Shan portion of the Tan‐Lu shear zone. While the metamorphic grade and width of deformation in rocks that record the two different dates vary significantly, such observations are not distinctive and could reflect multiple events at different depths or overprinting in an evolving shear zone (e.g., Dyck et al., 2021). Perhaps more revealing is that the foliation developed in the main phase amphibolite facies shear zone is crosscut by Early Cretaceous dikes.…”

Metamorphic and intrusive history of the Hindu Raj region, northern Pakistan

“…MnNCKFMASHTO) chemical system using the internally consistent thermodynamic dataset ds-55 of Powell (1998) (updated to August 2004) and activitycomposition relations for melt, biotite and ilmenite (White et al 2007), feldspar (Holland & Powell, 2003), white mica (Coggon & Holland, 2002) and garnet (White et al 2007). Dataset ds-55 was chosen over the more recent ds-62 because it better predicted the observed mineral assemblages, and in particular, the composition and stability of garnet in our samples (c.f., Dyck et al 2020;Dyck et al 2021). The amount of water was set to minimally saturate the assemblage in the immediate sub-solidus at 0.7 GPa.…”

Evidence for Post‐Assembly Modification of Western Laurentia by Back‐Arc Extension

“…To the southwest, a buried subsurface extension of the GSLSZ with slightly younger displacement is identified as the Hay River Fault (HRF; E. Wang, Unsworth, & Chacko, 2018). Exhumed mylonites within the GSLSZ record deformation at mid‐crustal depth (Dyck et al., 2021), while the HRF documents a later phase of brittle faulting (Hanmer et al., 1992). The GSLSZ offsets the Thelon magmatic zone from magmatic zones in northern Alberta and represents a continental transform fault that formed synchronously with oblique indentation of the Rae and Hearne province by the Slave province (Eaton & Hope, 2003; Eaton et al., 2004; Hanmer et al., 1992; D. Pana et al., 2001).…”

“…3.2‐3.0 Ga and 2.4‐2.14 Ga). Based on the chemistry of the granitoid rocks, 1.99‐1.9 Ga magmatism within the TMZ is inferred to be a result of crustal thickening within a plate‐interior setting (Chacko et al., 2000; Dyck et al., 2021). In their model, magma generation occurs primarily in the mid‐to lower crust as a consequence of the thickening of the heat‐producing layer in the upper crust.…”

“…3.2-3.0 Ga and 2.4-2.14 Ga). Based on the chemistry of the granitoid rocks, 1.99-1.9 Ga magmatism within the TMZ is inferred to be a result of crustal thickening within a plate-interior setting (Chacko et al, 2000;Dyck et al, 2021).…”