The Tatshenshini shear zone (new) in southwestern Yukon, Canada: Comparison with the Coast shear zone in British Columbia and southeastern Alaska and implications regarding the Shakwak suture

Abstract

Abstract.The Tatshenshini

Landscape antiquity and Cenozoic drainage development of southern Yukon, through restoration modeling of the Tintina Fault

“…The surface is locally overlain by mid-and Lower Cretaceous rhyolitic volcanic rocks (Gordey 1988(Gordey , 2013Bacon et al 1990Bacon et al , 2014, and early Cenozoic magmatism at 50-60 Ma produced felsic and mafic intrusive and extrusive rocks, sporadically distributed in central and east-central Alaska and adjacent western Yukon (Jackson et al 1986;Dusel-Bacon et al 2016, and references therein). In southern Yukon, the surface of the Yukon plateaus is best preserved beyond the limits of regional glaciation; principally in the Klondike Plateau where only limited alpine glaciation occurred during the late Pliocene or earliest Pleistocene (Lowey 2000;Nelson and Jackson 2003;Jackson et al 2009).…”

Crustal architecture of SW Yukon, northern Cordillera: Implications for crustal growth in a convergent margin orogen

“…VR, vitrinite reflectance; CAI, conodont alteration index; Zrn, zircon age; Tit, titanite age; Mon, monazite age; xt, xenotime age; CPC, Coast plutonic complex. References: 1, Johnasson et al [1997]; 2, Hart [1997]; 3, Johnston et al [1996]; 4, Johnston and Erdmer [1995a, 1995b]; 5, Erdmer and Mortensen [1993]; 6, Mezger et al [2001a]; 7, Mezger et al [2001b]; [8] Lowey [2000].…”

“…Open to tight, symmetric to highly asymmetric west verging folds are locally responsible for westward overturning of large panels of rocks, postdate mid‐Cretaceous intrusions, and are thought to have developed during Late Cretaceous to Tertiary thrust emplacement of Kluane Metamorphic Assemblage on Dezadeash Group [ Eisbacher , 1976]. A mylonite zone bounding the Dezadeash Group to the east is characterized by top to the southwest kinematic indicators [ Lowey , 2000] and may be an expression of the thrust fault that places the Kluane Metamorphic Assemblage above the Dezadeash Group.…”

“…More mafic, early phases of the intrusion are boudinaged [ Mezger , 2003]. Locally, mylonites in the Ruby Range batholith can be followed along strike into shear zones in the footwall of the batholith [ Lowey , 2000]. Kinematic indicators viewed on planes perpendicular to foliation that contain the mineral‐stretching lineation include bookshelf faulted mineral grains, C‐S fabrics, and C′ extensional shears.…”

“…We compiled structural orientation data for layering (bedding and foliation) from available 1:250,000 and 1:50,000 scale regional geological maps for southwest Yukon northeast of the Denali fault (data sources for 1:250,000 geology maps, southwest Yukon are Fyles et al [1961], Kindle [1953], Muller and Christie [1966], and Tempelman‐Kluit [1974b, 1974c]). These data were compared against structural data from more detailed studies [ Erdmer , 1989, 1990, 1991; Lowey , 2000; Mezger , 2003] for consistency. To facilitate structural analysis, the region was divided into 1:50,000 scale map sheets and foliation data plotted for each map sheet 1:250,000 scale domains were then defined based on consistency of structural plunge (Figure 3).…”