Circum-Arctic Lithosphere Evolution (CALE) Transect C: displacement of the Arctic Alaska–Chukotka microplate towards the Pacific during opening of the Amerasia Basin of the Arctic

Abstract

This paper synthesizes the framework and geological evolution of the Arctic Alaska–Chukotka microplate (AACM), from its origin as part of the continental platform fringing Baltica and Laurentia to its southward motion during the formation of the Amerasia Basin (Arctic Ocean) and its progressive modification as part of the dynamic northern palaeo-Pacific margin. A synthesis of the available data refines the crustal identity, limits and history of the AACM and, together with regional geological constraints, provides a tectonic framework to aid in its pre-Cretaceous restoration. Recently published seismic reflection data and interpretations, integrated with regional geological constraints, provide the basis for a new crustal transect (the Circum-Arctic Lithosphere Evolution (‘CALE’) Transect C) linking the Amerasia Basin and the Pacific margin along two paths that span 5100 km from the Lomonosov Ridge (near the North Pole), across the Amerasia Basin, Chukchi Sea and Bering Sea, and ending at the subducting Pacific plate margin in the Aleutian Islands. We propose a new plate tectonic model in which the AACM originated as part of a re-entrant in the palaeo-Pacific margin and moved to its present position during slab-related magmatism and the southward retreat of palaeo-Pacific subduction, largely coeval with the rifting and formation of the Amerasia Basin in its wake.

Significance of Northeast‐Trending Features in Canada Basin, Arctic Ocean

“…Similarities in seismic stratigraphy and interpreted deformation support this rotational closure (Houseknecht & Connors, ). Recently acquired seismic reflection and refraction data from the Canada Basin (Chian et al, ) and plate reconstruction models (Amato et al, ; Doré et al, ; Miller et al, ; Shephard et al, ) are generally consistent with the rotational opening model.…”

“…Geologic and geophysical evidence support the interpretation that northeast‐trending structures within the Chukchi Borderland are essentially continuous with similar structures on the Chukchi Shelf. Seismic observations from the Chukchi Sea shelf and southern Chukchi Borderland, and descriptions and quantitative geochronology and thermochronology of dredge samples from the northern Chukchi Borderland demonstrate fundamental differences in pre‐Mississippian basement rocks between the Chukchi Platform and Plateau on the west and the Hanna Trough, Northwind Basin, and Northwind Ridge on the east (Connors & Houseknecht, ; Ilhan & Coakley, ; Kumar et al, ; Miller et al, ; O'Brien et al, ; Sherwood, ; Sherwood et al, ). Beneath the Chukchi Shelf, a crustal boundary is marked by a major change in reflectivity from transparent crust on the west to highly reflective crust on the east beneath Hanna Trough (Kumar et al, ).…”

Age of the Canada Basin, Arctic Ocean: Indications From High‐Resolution Magnetic Data

“…Halgedahl and Jarrard (1987) suggested that the Alaskan North Slope was still adjacent to the Arctic Islands in Valanginian based on the paleomagnetic data from the North Slope Kuparuk Formation. Based on a petrological study, Miller et al (2017) suggested that spreading in the Amerasia Basin may have ended at~90 Ma. Based on a petrological study, Miller et al (2017) suggested that spreading in the Amerasia Basin may have ended at~90 Ma.…”

“…Based on the onshore and along-margin geological evidences, the age of the Canada Basin is not older than Late Jurassic (~160 Ma) and not younger than Late Cretaceous (~72 Ma) (e.g., Embry, 1990;Gaina et al, 2014;Grantz et al, 2011;Miller et al, 2006Miller et al, , 2017Taylor et al, 1981). Since the deep-tow magnetic anomalies are rather strong (up to 400 nT) and well marked, we do not expect that they formed during the so-called "Jurassic quiet zone" (>157 Ma) characterized by numerous polarity reversals and a weak geomagnetic intensity or during the Cretaceous quiet zone (~120.6 (124)-83 Ma) characterized by a constant (or very dominant) normal polarity (Granot et al, 2012).…”

“…However, the nature and age of the Amerasia Basin have been debated for decades (e.g., Embry, 1990Embry, , 2000Grantz et al, 1998Grantz et al, , 2011Lane, 1997;Miller et al, 2006Miller et al, , 2017. Nevertheless, the age of the Canada Basin remains elusive, with an inferred range of 160-72 Ma from investigations on the stratigraphy and volcanism along its margins and sparse geophysical data in the basin [e.g., Alvey et al, 2008;Chian et al, 2016;Døssing et al, 2013Døssing et al, , 2017Embry,1990;Gaina et al, 2014;Grantz et al, 2011;Lane,1997;Langseth et al, 1990;Miller et al, 2006Miller et al, , 2017Taylor et al, 1981]. The roughly symmetric oceanic lithosphere about a N-S trending gravity low indicates that the Canada Basin was an E-W spreading oceanic basin.…”