Geological map including geological cross sections and mineral occurrences.

The Joe Mountain map area, northeast of Whitehorse, is underlain by folded, Upper Triassic and Jurassic sedimentary and volcanic strata of the Whitehorse Trough which are intruded by north-trending Cretaceous plutons. Volcanic rocks previously mapped as ""Volcanics of uncertain age"" and Hutshi Group are Triassic in age and comprise three mappable units dominated by thick accumulations of basaltic and andesitic, aphyric pillowed volcanics. The volcanics, and associated sedimentary rocks dominate the eastern part of the map area whereas a thick carbonate assemblage dominates the Upper Triassic stratigraphy in the western part of the map area. The east-west transition represents either a sharp facies change across the map area or a structural juxtaposition. Numerous through-going, north-trending faults which cut the region may originate from motion along the interpreted Lake Laberge Fault Zone which underlies the Yukon River/Lake Laberge valley. Potential mineral deposits in this map area include copper (gold-molybdenum-tungsten) skarns and gold-bearing quartz veins. Regional silt geochemistry indicates that the distribution of the Triassic volcanic suites is spatially coincident with regionally extensive, gold-in-silt anomalies. The source of these anomalies is uncertain and provide for intriguing prospecting targets.

not_specified

not_specified

Stratigraphic and structural relationships within Stikinia, and overlap assemblages of the Whitehorse trough, are investigated in the Teslin Mountain area, southern Yukon. The Middle Triassic Joe Mountain Formation is dominated by a thick sequence of aphyric basalt produced by subaqueous volcanism. The Upper Triassic Lewes River Group displays complex lateral and vertical lithological and facies changes. It illustrates synvolcanic terrane exhumation, with erosion of the volcanic upland leading to deposition of thick volcaniclastic sequences, in parallel with ongoing clastic and carbonate sedimentation in marginal basins. Unravelling the Lewes River Group stratigraphy is critical in understanding the latest stages of Stikinia arc volcanism and the onset of Whitehorse trough marine sedimentation in the Early-Middle Jurassic. Further mapping and analytical work will focus at characterizing the Joe Mountain Formation and Lewes River Group, to determine how Stikinia evolved prior to final amalgamation of the Intermontane terranes with North America.

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.

not_specified

not_specified

not_specified