Mesozoic and Cenozoic tectonics of the eastern and central Alaska Range: Progressive basin development and deformation in a suture zone

Abstract

Analysis of late Mesozoic and Cenozoic sedimentary basins, metamorphic rocks, and major faults in the eastern and central Alaska Range documents the progressive development of a suture zone that formed as a result of collision of an island-arc assemblage (the Wrangellia composite terrane) with the former North American continental margin. New basin-analysis, structural, and geochronologic data indicate the following stages in the development of the suture zone: (1) Deposition of 3-5 km of Upper Jurassic-Upper Cretaceous marine strata (the Kahiltna assemblage) recorded the initial collision of the island-arc assemblage with the continental margin. The Kahiltna assemblage exposed in the northern Talkeetna Mountains represents a Kimmeridgian-Valanginian backarc basin that was filled by northwestward-flowing submarine-fan systems that were transporting sediment derived from Mesozoic strata of the island-arc assemblage. The Kahiltna assemblage exposed in the southern Alaska Range represents a Valanginian-Cenomanian remnant ocean basin filled

Intermediate to felsic middle crust in the accreted Talkeetna arc, the Alaska Peninsula and Kodiak Island, Alaska: An analogue for low‐velocity middle crust in modern arcs

“…Overlap assemblages suggest that the two terranes formed as a single tectonic block or were juxtaposed prior to accretion onto the continental margin [Plafker et al, 1989;Nokleberg et al, 1994]. The Peninsular and Wrangellia terranes lie outboard of the Kahiltna terrane (Figure 1), a thick section of flysch and turbidite deposits [Nokleberg et al, 1994] interpreted to represent back-arc sedimentary sequences that were deformed during Jurassic to Cretaceous docking of the terranes [Wallace et al, 1989;Ridgway et al, 2002]. To the south, the Talkeetna section is juxtaposed with coeval and younger accretionary complexes of the Chugach terrane across the Border Ranges fault system (Figure 1) [Sisson and Onstott, 1986;Pavlis et al, 1988;Roeske et al, 1989;Clift et al, 2005b].…”

Arc and Slab-Failure Magmatism in Cordilleran Batholiths I – The Cretaceous Coastal Batholith of Peru and its Role in South American Orogenesis and Hemispheric Subduction Flip

“…In Alaska, rocks of the Valanginian-Cenomanian Kahiltna basin were metamorphosed and thrust northward at ~74 Ma, coincident with development of the Campanian-Maastrichtian Cantwell basin, a thrust-top basin formed during the deformation caused by the accretion of Wrangellia to the paleo-Alaskan margin along a well-defined geophysical and detrital zircon provenance break (Ridgway et al 2002;Trop and Ridgway 2007;Hults et al 2013). Late CretaceousEarly Tertiary northward-vergent thrusts and folds also deformed Early Cretaceous features in northern Alaska, including apparent basement duplexing in the Brooks Range (Moore et al 1997).…”

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

“…The entire Rocky Mountain fold-thrust belt of the Canadian sector (Price 1981) and its Late Cretaceous-Early Tertiary foredeep must be younger than Santonian, the age of marine mudstones in the footwall syncline to the Bourgeau thrust, the westernmost of the large thrusts that cut the North American platform terrace (Larson et al 2006;Price 2013). Within Alaska, sedimentary rocks of the Kahiltna Basin were folded and thrust northward coincident with kyanite-grade metamorphism and the development of the Campanian-Maastrichtian Cantwell thrust-top basin (Ridgway et al 2002;Trop and Ridgway 2007). The hypsometry of the modern Brooks Range was caused by thick-skinned Laramide thrusting (Moore et al 1997).…”