Skip to Main Content
Book Chapter

Upper Triassic continental margin strata of the central Alaska Range: Implications for paleogeographic reconstruction

By
Alison B. Till
Alison B. Till
1
U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508, USA
Search for other works by this author on:
A. G. Harris
A. G. Harris
2
U.S. Geological Survey, Emeritus, 1523 E. Hillsboro Boulevard, No. 1031 Deerfield Beach, Florida 33441, USA
Search for other works by this author on:
Bruce R. Wardlaw
Bruce R. Wardlaw
3
U.S. Geological Survey, 12201 Sunrise Valley Drive, Reston, Virginia 22092, USA
Search for other works by this author on:
M. Mullen
M. Mullen
4
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, USA
Search for other works by this author on:
Published:
January 01, 2007

Remnants of a Late Triassic continental margin and ocean basin are scattered across central and southern Alaska. Little is known about the fundamental nature of the margin because most remnants have not been studied in detail and a protracted period of terrane accretion and margin-parallel translation has disrupted original stratigraphic and structural relationships.

Three new conodont collections were recovered from a sequence of Upper Triassic calcareous sedimentary rocks in the central Alaska Range. One of the three localities is north of the Denali fault system in an area previously thought to be underlain by an uninterrupted sequence of metamorphic rocks of the parautochthonous Yukon-Tanana terrane. Structural relations in the immediate vicinity of this conodont locality indicate that mid-Cretaceous(?) thrust faulting imbricated Paleozoic metaigneous rocks with the Triassic sedimentary rocks. This may reflect a closer pre-Cretaceous relationship between the Yukon-Tanana terrane and Late Triassic shelf and slope deposits than previously appreciated.

Reexamination of existing conodont collections from the central Alaska Range indicates that Upper Triassic marine slope and basin rocks range in age from at least as old as the late Carnian to the early middle Norian. The conodont assemblages typical of these rocks are generally cosmopolitan and do not define a distinct paleogeographic faunal realm. One collection, however, contains Epigondolella multidentata sensu Orchard 1991c, which appears to be restricted to western North American autochthonous rocks. Although paleogeographic relations cannot be determined with specificity, the present distribution of biofaces within the Upper Triassic sequence could not have been the result of simple accordion-style collapse of the Late Triassic margin.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Tectonic Growth of a Collisional Continental Margin: Crustal Evolution of Southern Alaska

Kenneth D. Ridgway
Kenneth D. Ridgway
Search for other works by this author on:
Jeffrey M. Trop
Jeffrey M. Trop
Search for other works by this author on:
Jonathan M.G. Glen
Jonathan M.G. Glen
Search for other works by this author on:
J. Michael O'Neill
J. Michael O'Neill
Search for other works by this author on:
Geological Society of America
Volume
431
ISBN print:
9780813724317
Publication date:
January 01, 2007

References

Related

Citing Books via

Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal