T198 Assembling Laurentia: Paleozoic Mobile Margins I

Thursday, 29 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

STRATIGRAPHIC RECORD AND GEOLOGIC CONFIGURATION OF THE LATE PALEOZOIC-MESOZOIC NORTHWESTERN LAURENTIAN MARGIN: A RE-EVALUATION OF UPPER PALEOZOIC-CRETACEOUS STRATA, DENALI NATIONAL PARK AND PRESERVE, CENTRAL ALASKA RANGE

Paper number: T198-16
Program: Technical Sessions
Time: 5:05 PM – 5:20 PM

Authors

Abstract

The stratigraphic record of the late Paleozoic-mid Mesozoic evolution of the western Laurentian margin remains difficult to constrain in many parts of the northern Cordillera. While the record of sedimentary basins has been well-integrated into the study of Jurassic-Cretaceous collisional tectonics, the late Paleozoic-mid Mesozoic stratigraphic record along the margin has largely been dismembered by strike-slip tectonics and lacks robust correlations. Pre-Cretaceous stratigraphy of the central Alaska Range remains especially understudied and currently hinders a more complete integration of data along the margin. Results of our study highlight the juxtaposition of two distinct late Paleozoic-early Mesozoic stratigraphic assemblages exposed along the northern and southern margins of Denali National Park and Preserve. The northern package is comprised of submarine fan deposits unconformably overlain by fluvial conglomerate and sandstone. Proterozoic and early Paleozoic detrital zircon populations are most consistent with recycled sources common to Ellesmerian clastic wedge and the Baltican craton. We broadly correlate this assemblage with Late Triassic-Early Jurassic continental margin assemblages exposed in eastern Alaska and the Yukon. The southern package is comprised of Permian-mid Triassic submarine fan deposits and Late Triassic pillow basalts. We correlate this assemblage with the Mystic (sub)terrane, an accreted terrane of Arctic affinity exposed in the western Alaska Range. Silurian and early Permian populations in Permian strata of the southern package are most consistent with sources associated with the Alexander and Wrangellia terranes and may indicate interaction between these terranes in association with the early Permian Browns Fork orogeny. Both stratigraphic packages are depositionally overlain by Jurassic-Cretaceous flysch and the Upper Cretaceous Cantwell Formation that comprise part of the Alaska Range suture zone. The results of our study improve our understanding of the paleogeographic configuration of the late Paleozoic-mid Mesozoic western Laurentian margin with emphasis on the juxtaposition of Arctic and peri-cratonic stratigraphy in the central Alaska Range.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-348595

© Copyright 2020 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.