"Subduction erosion of the Jurassic Talkeetna-Bonanza arc and the Mesozoic accretionary tectonics of western North America" by Peter D. Clift

Article

Subduction erosion of the Jurassic Talkeetna-Bonanza arc and the Mesozoic accretionary tectonics of western North America

Geology (2005)

Peter D. Clift, University of Aberdeen
Terry Pavlis, University of New Orleans
Susan M. DeBari, Western Washington University
Amy E. Draut, University of California, Santa Cruz
Matthew Rioux, University of California, Santa Barbara
Peter B. Kelemen, Lamont–Doherty Earth Observatory

Link

Abstract

The Jurassic Talkeetna volcanic arc of south-central Alaska is an oceanic island arc that formed far from the North American margin. Geochronological, geochemical, and structural data indicate that the arc formed above a north-dipping subduction zone after ca. 201 Ma. Magmatism migrated northward into the region of the Talkeetna Mountains ca. 180 Ma. We interpret this magmatism as the product of removal of the original forearc while the arc was active, mainly by tectonic erosion. Rapid exhumation of the arc after ca. 160 Ma coincided with the sedimentation of the coarse clastic Naknek Formation. This exhumation event is interpreted to reflect collision of the Talkeetna arc with either the active margin of North America or the Wrangellia composite terrane to the north along a second north-dipping subduction zone. The juxtaposition of accreted trench sedimentary rocks (Chugach terrane) against the base of the Talkeetna arc sequence requires a change from a state of tectonic erosion to accretion, probably during the Late Jurassic (before 150 Ma), and definitely before the Early Cretaceous (ca. 125 Ma). The change from erosion to accretion probably reflects increasing sediment flux to the trench due to collision ca. 160 Ma.

Keywords

Alaska,
Terrane accretion,
Subduction,
Tectonic erosion,
Collision

Disciplines

Publication Date

November 1, 2005

DOI

10.1130/G21822.1

Publisher Statement

The Geological Society of America

Citation Information

Clift, P. D., T. Pavlis, S. M. DeBari, A. E. Draut, M. Rioux, P. B. Kelemen (2005) Subduction erosion of the Jurassic Talkeetna-Bonanza arc and the Mesozoic accretionary tectonics of western North America, Geology, v. 33, no. 11, p. 881-884.