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TitleLandscape antiquity and Cenozoic drainage development of southern Yukon, through restoration modeling of the Tintina Fault
AuthorRyan, J J; Hayward, N; Jackson, L E, Jr
SourceCanadian Journal of Earth Sciences vol. 54, no. 10, 2017 p. 1085-1100,
Alt SeriesEarth Sciences Sector, Contribution Series 20160421
PublisherNRC Research Press/Canadian Science Publishing
Mediapaper; on-line; digital
File formatpdf; pptx
ProvinceYukon; Northwest Territories; British Columbia
AreaYukon River; Alaska; United States
Lat/Long WENS-150.0000 -120.0000 66.0000 59.0000
Subjectsgeophysics; surficial geology/geomorphology; displacement; faults; drainage; drainage systems; digital terrain modelling; seismic zones; tectonic environments; paleohydrology; paleodrainage; Klondike Plateau; Tintina Fault; Cretaceous; Mesozoic
Illustrationslocation maps; digital elevation models
ProgramWestern Cordillera, Redefinition of crustal blocks, GEM2: Geo-mapping for Energy and Minerals
AbstractThe impact of Tintina Fault displacement on the development of the Yukon River and drainage basins of central Yukon is investigated through geophysical and hydrological modeling of digital terrain model data. Regional geological evidence suggests that the age of the planation of the Klondike Plateau is at least Late Cretaceous, rather than Neogene as previously assumed, and that surprisingly there has been little net incision in the region since the late Mesozoic. The Tintina Fault has been previously interpreted to have experienced ~430 km of dextral displacement, primarily during the Eocene. However, the alignment of river channels across the fault at specific displacements, coupled with recent seismic events and related fault activity, suggests that the fault may have moved in stages over a longer time span. Topographic restoration and hydrological models show that the drainage of the Yukon River northwestward into Alaska via the ancestral Kwikhpak River was only possible at restored displacements of up to ~50-55 km on the Tintina Fault. We interpret the published drainage reversals convincingly attributed to the effects of Pliocene glaciation as an overprint on earlier Yukon River reversals attributed to tectonic displacements along the Tintina Fault. At restored displacements between 230 and 430 km, our models illustrate that paleo-Yukon River drainage may have flowed eastward into the continental interior via an ancestral Liard River. The revised drainage evolution has wide-reaching implications for surficial geology deposits, the flow direction and channel geometries of the region's ancient rivers, and importantly, for exploration of placer gold deposits.
Summary(Plain Language Summary, not published)
The development of rivers and evolution of the landscape in Yukon during the past ~65 million years is investigated in relation to motion on the Tintina fault. The NW-striking fault, which crosses central Yukon, experienced ~430 km of Cenozoic (younger than 65 million years) movement. The potential impact of fault movement on the development of the many rivers which flow across it is investigated through landscape modeling. Past fault movements are undone by sliding the topography backwards in time along the fault trace. At selected positions of topographic displacement along the fault, a modeled prediction of the locations and flow directions of past rivers is made. The models illustrate how fault motion caused a reversal of river flow directions, altered drainage patterns, and suggest that prior to fault movement, the rivers of central Yukon flowed east towards the continent, rather than in the present northwest direction.