T143 Insights into Cordilleran Tectonics and Magmatism from the Sedimentary Record

Tuesday, 12 October 2021
8:00 AM - 12:00 PM
Portland Ballroom 255 (Hybrid Room)

LATE MESOZOIC TERRANE ASSEMBLY IN THE NORTHWESTERN CORDILLERA THROUGH THE LENS OF SILICICLASTIC SUCCESSIONS IN EASTERN INTERIOR ALASKA

Paper number: T143-8
Program: Technical Sessions
Time: 9:40 AM – 9:55 AM

Authors

Abstract

New geologic mapping and detrital zircon geochronology help to define age and provenance patterns of Mesozoic siliciclastic strata from the Manley basin in eastern interior Alaska that provide essential constraints on the assembly of accreted terranes in the northwestern Cordillera. Successions including the Wolverine quartzite and Wilber Creek/Minto units were deposited on pericratonic terranes such as Yukon-Tanana, Farewell/Livengood, and Ruby outboard of the northwestern Laurentia margin. The successions presently define a complex suture zone between the pericratonic terranes that has accommodated hundreds of km of shortening and strike-slip translation. On the northwestern side of the basin, the Late Jurassic–Early Cretaceous Wolverine quartzite appears restricted to the Ruby and (or) Livengood terranes. Circa 159–131 Ma maximum depositional ages from the quartz-rich Wolverine confirm limited fossil ages, and diverse older age populations suggest recycling of the Ruby and (or) Farewell terranes. To the southeast, the Lower Cretaceous Wilber Creek and Upper Cretaceous Minto units are less compositionally and texturally mature and have prominent ca. 200–150 Ma zircon age populations suggesting Yukon-Tanana terrane igneous sources. The successions and associated pericratonic terranes are all presently interleaved in folded and faulted panels that also contain slivers of other allochthonous terranes. Distinct provenance on either side of the Manley basin suggests that major shortening began in the Late Cretaceous and was likely completed prior to ca. 60 Ma plutonism that cross-cuts all of the deformed successions. Subsequent strike-slip displacement along major structures such as the Tintina and Victoria Creek faults continued to modify the terrane and suture zone geometries. Continuing work on the provenance and structural evolution of the siliciclastic successions will help further refine tectonic models for accretionary orogenesis at the apex of the Cordillera.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-365279

© Copyright 2021 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.