Skip to Main Content
Book Chapter

Geology of Seward Peninsula and Saint Lawrence Island

By
Alison B. Till
Alison B. Till
U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508–4667
Search for other works by this author on:
Julie A. Dumoulin
Julie A. Dumoulin
U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508–4667
Search for other works by this author on:
Published:
January 01, 1994

Abstract

Seward Peninsula (Fig. 1) may be divided into two geologic terranes (Fig. 2) on the basis of stratigraphy, structure, and metamorphic history. The Seward terrane, an area 150 by 150 km in the central and eastern peninsula, is dominated by Precambrian(?) and early Paleozoic blueschist-, greenschist-, and amphibolitefacies schist and marble, and intruded by three suites of granitic rocks. The York terrane, roughly 100 by 75 km, occupies western Seward Peninsula and the Bering Straits region; it is composed of Ordovician, Silurian, Devonian, Mississippian, and possibly older limestone, argillaceous limestone, dolostone, and phyllite, which are cut by a suite of Late Cretaceous tin-bearing granites. The boundary between the Seward and York terranes is poorly exposed but is thought to be a major thrust fault because of its sinuous map trace, a discontinuity in metamorphic grade, and differences in stratigraphy across the boundary (Travis Hudson, oral communication, 1984). The boundary between the Seward terrane and the Yukon-Koyukuk province to the east is complicated by vertical faults (the Kugruk fault zone of Sainsbury, 1974) and obscured by Cretaceous and Tertiary cover.

The Seward Peninsula heretofore was thought to consist largely of rocks of Precambrian age (Sainsbury, 1972, 1974, 1975; Hudson, 1977). Microfossil data, however, indicate that many of the rocks considered to be Precambrian are early Paleozoic in age (Till and others, 1986; Dumoulin and Harris, 1984; Dumoulin and Till, 1985; Till and others, 1983; Vandervoort, 1985). It is likely that Precambrian rocks are a minor part of the stratigraphy of the Seward Peninsula.

You do not currently have access to this article.

Figures & Tables

Contents

DNAG, Geology of North America

The Geology of Alaska

George Plafker
George Plafker
U.S. Geological Survey MS 904, 345 Middlefield Road Menlo Park, California 94025
Search for other works by this author on:
Henry C. Berg
Henry C. Berg
115 Malvern Avenue Fullerton, California 92632
Search for other works by this author on:
Geological Society of America
Volume
G-1
ISBN electronic:
9780813754536
Publication date:
January 01, 1994

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal