Devonian–Carboniferous paleogeography and orogenesis, northern Yukon and adjacent Arctic Alaska

Abstract

Surface and subsurface data from northern Yukon document a northward facies transition from shelf carbonates to basinal graptolitic shales and cherts from Late Cambrian to Early Devonian time. Parts of this north-facing continental margin were deformed during separate orogenic events of Early Devonian and Early Carboniferous ages. The first event, the Romanzof Orogeny, is identified in exposures across northwestern Yukon, in adjacent northeastern Alaska, and locally in the subsurface of the Alaska North Slope. It resulted in tight folds, north-directed thrust faults, and intrusion by Late Devonian posttectonic granitic plutons. Notwithstanding the thrust-fault orientations, southward diminution of deformation intensity combined with facies variations suggest that tectonic transport was generally southward. Evidence for an Early Carboniferous event is preserved in the northern Richardson Mountains and locally in the subsurface of the Mackenzie Delta region. It consists of detached open folds and minor thrust faults. Geological and geophysical data from northern Yukon document the location and orientation of the Early Carboniferous deformation front, and define a regional tectonic transport direction toward the south or southeast. This event is a distal foreland element of the Ellesmerian Orogeny (sensu stricto) of the Canadian Arctic Islands and is distinct from the Romanzof event in age, intensity, and extent. Endicott and Lisburne group strata, deposited on a southwest-facing subsiding shelf, overstep rocks deformed by the Romanzof event even as Ellesmerian deformation encroached from the north.

Chapter 5 Palaeogeographic and tectonic evolution of the Arctic region during the Palaeozoic

“…Such a location of the North Slope subterrane with respect to Siberia (locations shown on Fig. 5.4) follows the geology for the North Slope subterrane of the Arctic Alaska block discussed in Lane (2007) and in Macdonald et al (2009). It fits the Palaeozoic links based on mega-fossils as proposed by Blodgett et al (2002) and also satisfies the tectonics of the future Hammond terrane (Fig.…”

Provenance of North American Triassic strata from west-central and southeastern Yukon: correlations with coeval strata in the Western Canada Sedimentary Basin and Canadian Arctic Islands

“…950-1150 Ma correspond with Pennsylvanian to Triassic strata of the Northwest Laurentian and Arctic reference frames (Figs. 9L, 9M, 9O-9Q; Gehrels and Ross 1998;Miller et al 2006 (Trettin et al 1987) and the Ellesmerian foreland in northern Yukon (Lane 2007).…”

Fold belts and sedimentary basins of the Eurasian Arctic

“…The sub-Mississippian unconformity post-dates Early Devonian deformation (the Romanzof Orogeny of the eastern Brooks Range, see [84]) and is present in all autochthonous and parautochthonous sequences of northern Brooks Range [99,160]. There is no analogous unconformity known on Wrangel Island, perhaps due to poor exposure.…”