Three events of Paleoproterozoic deformation are recognized in schist of the Fairchild Lake Group (Wernecke Supergroup) in the Wernecke Mountains. The first event produced a chloritoid ± garnet and opaque porphyroblastic, chloritoid-chlorite-muscovite-quartz schist. Pressure-temperature conditions have been estimated to lie between 3-6 kbar and 450-550°C. The second event produced a crenulation, and the third generated kink bands. All of these features are crosscut by 1.60 Ga Wernecke Breccia. These events are regarded as products of the Racklan Orogeny, a Paleoproterozoic interval of orogenesis, which favourably correlates with the Fifteenmile Orogeny in the Ogilvie Mountains of western Yukon and the Forward Orogeny in the Northwest Territories.

The tectonic evolution of the Whitehorse trough in central Yukon is largely preserved by the Early to Middle Jurassic Laberge Group, an ~3000-m thick succession of synorogenic clastic strata that unconformably overlies arc and arc marginal rocks of the Lewes River Group. A two-year project was initiated to test a Sinemurian to Toarcian transgression of basal Laberge Group strata westward across the Whitehorse trough and examine the regional relationships between the timing of Jurassic exhumation, sedimentation, and terrane accretion in the northern Canadian Cordillera. Field studies in 2017 targeted basal Laberge Group strata at seven locations in central Yukon. At each field locality, basal Laberge Group strata are known or inferred to unconformably overlie the Povoas formation and multiple units of the Aksala formation. Pre-Early Jurassic unconformities may indicate variable basin topography due to the complex internal stratigraphy of the Lewes River Group, or that regional exhumation and erosion affected the Whitehorse trough prior to Laberge Group sedimentation.

The Division Mountain area is underlain primarily by Jurassic to Cretaceous(?) sedimentary rocks of the Laberge Group and Tantalus Formation. The Laberge Group is divisible into the following informal units: the Richthofen, Nordenskiöld, Conglomerate, and Tanglefoot formations. The Tanglefoot, which comprises a large portion of the exposed strata at Division Mountain, is here subdivided into the lower and upper members. The lower member consists of quartz-rich sandstone, grit, polymicitic conglomerate and laminated siltstone. The upper member is coal-bearing and typified by white grit, sandstone, and carbonaceous shale. The overlying Tantalus Formation is characterized by thick packages of resistant chert pebble conglomerate with intercalated sandstone beds, which form local highlands at Cub, Corduroy, Division, and Vowel mountains. The strata at Division Mountain are folded into several upright, tight northwest-trending anticlines and synclines with amplitudes of 2 to 7 km. The folded strata are intruded by feldspar-hornblende andesite sills and dykes. Organic matter identified within coal and siltstone of the Tanglefoot and Tantalus formations consists of Type III and subordinate Type I kerogen, suggesting the material is largely gas-prone. A combination of thermal maturation indicators (vitrinite reflectance and Tmax ) suggests that the coal and related strata are in the early to late stages of thermal diagenesis. Samples of the underlying Richthofen formation contain Type III kerogen matured beyond the oil window. Local folding and thickening of the Tanglefoot and Tantalus strata, as well as local intrusions in the Tanglefoot, may play a key role in the determination of hydrocarbon potential of the Division Mountain area.

Whitehorse trough is a northwestward-tapering belt of Upper Triassic to Lower Cretaceous volcanic and sedimentary rocks extending ~650 km from the British Columbia–Yukon border, north to the vicinity of Carmacks in south-central Yukon. It consists of three main stratigraphic units (i.e., the Lewes River Group, Laberge Group and Tantalus Formation) representing three sedimentary basins, partially overlapping in space and time. The Laberge Group (Lower-Middle Jurassic), informally subdivided into the Richthofen, Tanglefoot and Nordenskiold formations, was deposited in the Laberge basin, a collapsing fore-arc basin in which the arc was undergoing uplift and erosion. The Richthofen formation consists of conglomerate, massive sandstone, sandstone-mudstone couplets, volcaniclastic rocks and minor limestone interpreted as submarine fan systems. The Tanglefoot formation consists of coal-bearing sandstone, mudstone, conglomerate, volcaniclastic rocks and minor limestone interpreted as delta systems and shallow marine deposits. The Richthofen and Tanglefoot formations are the same age (i.e., Sinemurian to Bajocian), but the Richthofen formation is restricted to the southern half of the basin, whereas the Tanglefoot formation occurs in the northern half. The Nordenskiold formation consists of subaerially erupted, resedimented volcaniclastics deposited mainly during Pliensbachian time. The Richthofen formation is interpreted as a spent source rock and the Nordenskiold formation is not a source rock. The Tanglefoot formation is interpreted as a potential source rock and possibly an effective source rock. It contains petroleum fluid inclusions (mainly 23°- 32° and 40°- 44° API gravity) indicating a minimum trapping temperature of 110-115°C. The Tanglefoot formation is also a potential reservoir rock.

The Whitehorse Trough, south-central Yukon, originated as a Mesozoic fore-arc basin separating the allochthonous Stikine Terrane to the west from the North American craton. Late Triassic erosion of a volcanic arc supplied detritus to the basin. Subsequent cessation of volcanism, unroofing and deep erosion of the arc into the Middle Jurassic resulted in a progressive increase in granodioritic sediment. Late Triassic-Jurassic Laberge conglomerate within the Whitehorse Trough are coarse, polymictic and typically massive. Inverse or normal grading, planar stratification and cross-bedding are less common. Conglomerates are debris flow, sheet-flood and bar deposits of braided alluvial fan-deltas. These conglomerates usually overlie and grade basinward into feldspathic graywacke or arkosic sandstone. Crystal tuffs grade laterally into sandstone and occur as interbeds as well. Sandstones commonly display trough cross-bedding or planar stratification. Hummocky cross-stratification rarely occurs in sandstones interbedded with bioturbated silty mudstone. Other facies include graded sandstone-mudstone with Bouma BC(E) sequences; float-stone/micritic limestone and rare calcarenite/rudite. Sandstone-conglomerate facies transitions indicate a vertical progression from shallow marine and shoreface sedimentary strata of Late Triassic age to coarse alluvial fan conglomerates of Jurassic age, reflecting progradation of fan-delta systems with progressive infilling of the basin. The Stikine Terrane accreted to North America in the Late Jurassic with basin shallowing and closure reflected by changes in the sedimentary sequences.

Mica-quartz schist and olivine serpentinites form the Kluane metamorphic assemblage, a 150-km-long belt that is wedged between the Yukon-Tanana Terrane and the Insular Superterrane in the northern Coast Belt. The olivine serpentinites are serpentinized dunites that occur as lens-shaped bodies, interlayered along strike, with the mica-quartz schist. The larger ultramafic bodies developed a foliation and shear sense that is similarly oriented to those in the adjacent schist, suggesting 'Alpine-type' emplacement. Tectonic juxtaposition of schist and ultramafic rocks occurred during collapse and subduction of a back-arc basin underneath the North American continental margin in the Late Cretaceous. Oxygen isotope analyses point to values similar to known ophiolitic serpentinites. The ultramafic rocks are interpreted to be part of an oceanic crust that formed topographic highs during subduction and were subsequently sheared off and tectonically interleaved with metasedimentary rocks during the accretionary process.

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Regional-scale thrust faults in the Klondike District separate major lithologic units that include medium-grade metamorphic rocks of the Upper Permian Klondike Schist and middle to late Paleozoic Finlayson (Nasina) assemblage, as well as relatively low-grade greenstone and ultramafic rocks of the Slide Mountain terrane. These units were emplaced in the Jurassic as a series of kilometre-scale stacked thrust slices that are locally separated by additional ultramafic slices. A distinctive set of post-metamorphic compressional structures related to thrusting, particularly a set of ductile recumbent folds and associated spaced cleavage, is preserved in all thrust slices and is well developed near bounding faults. In carbonaceous units within the Klondike Schist, spatially associated with some thrusts, carbonaceous material is locally concentrated along the thrust-related spaced cleavage. Thrust-related fabrics are overprinted by kink-folding that locally affects the Finlayson assemblage, but is mainly developed in Klondike Schist. Gold-bearing veins appear confined to Klondike Schist and were emplaced in local sites of extension controlled principally by axial surfaces of these kink folds.

The Paleoproterozoic Wernecke Supergroup is a >13 km-thick metasedimentary succession exposed in the Wernecke, Ogilvie and Richardson mountains of central and northern Yukon. A program of field and laboratory investigations was initiated in 2007 in order to constrain the provenance, age and environment of deposition of the Wernecke Supergroup, as well as to better constrain the age of subsequent Proterozoic deformation (Racklan orogeny). Clastic and carbonate samples were collected from the Wernecke Supergroup for analysis of detrital and metamorphic minerals, as well as whole rocks, using a range of isotopic methods. Preliminary results from U-Pb analysis of detrital zircons from quartz sandstone beds, using ion probe mass spectrometry, are provided in this report. Patterns of the detrital zircon ages are broadly comparable to other Paleo- to Mesoproterozoic basins in Canada, suggesting a common Laurentian source. The maximum age of the Supergroup of 1.61 ± 0.03 Ga is provided by the age of the youngest detrital grain, which is ~0.1 Ga younger than expected.

Mafic volcanic and clastic strata of the Middle Triassic Joe Mountain Formation, east of Lake Laberge, Yukon, represent a juvenile volcanic arc sequence. Mafic volcanic rocks of the Upper Triassic Lewes River Group were formed in the spatial and temporal continuity of Joe Mountain volcanism. Carbonate sedimentation took place in shallow oceanic subbasins adjacent to the arc from the Carnian to Rhaetian; these subbasins were separated by physiographic boundaries inherent to the arc, resulting in lateral stratigraphic variations. Polymictic conglomerate and turbiditic sequences of the Lower-Middle Jurassic Laberge Group unconformably overlie Triassic rocks. Two north-northwest strike-slip faults, the Laurier Creek and the Goddard, control the distribution of units. Joe Mountain Formation rocks are characterized by an east-west structural trend, whereas the Upper Triassic and Jurassic sequences are characterized by north-northwest trending tight folds and thrust faults. At least five post-accretion igneous suites intrude or overlie older stratigraphy, including the Late Cretaceous Open Creek volcanic complex.