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Lead-alpha age determinations of granitic rocks from Alaska

Trace Elements Investigations 618

This report concerns work done on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission
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Abstract

Lead-alpha activity age determinations were made on zircon from seven granitic rocks of central and southeastern Alaska. The results of the age determinations indicate two periods of igneous intrusion, one about 95 million years ago, during the Cretaceous period, and another about 53 million years ago, during the early part of the Tertiary. The individual ages determined on zircon from 2 rocks from southeastern Alaska and 1 from east-central Alaska gave results of 90, 100, and 96 million years; those determined on 4 rocks from central Alaska gave results of 47, 56, 58, and 51 million years.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Lead-alpha age determinations of granitic rocks from Alaska
Series title:
Trace Elements Investigations
Series number:
618
Year Published:
1957
Language:
English
Publisher:
U.S. Geological Survey
Description:
27 p.
Number of Pages:
28
Country:
United States
State:
Alaska