thumbnail

Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska

Professional Paper 1709-D

By:
, ,

Links

Abstract

High-precision 40Ar/39Ar geochronology of selected lavas from Westdahl Volcano places time constraints on several key prehistoric eruptive phases of this large active volcano. A dike cutting old pyroclastic-flow and associated lahar deposits from a precursor volcano yields an age of 1,654+/-11 k.y., dating this precursor volcano as older than early Pleistocene. A total of 11 geographically distributed lavas with ages ranging from 47+/-14 to 127+/-2 k.y. date construction of the Westdahl volcanic center. Lava flows cut by an apparent caldera-rim structure yielded ages of 81+/-5 and 121+/-8 k.y., placing a maximum date of 81 ka on caldera formation. Late Pleistocene and Holocene lavas fill the caldera, but most of them are obscured by the large summit icecap.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Argon geochronology of late Pleistocene to Holocene Westdahl volcano, Unimak Island, Alaska
Series title:
Professional Paper
Series number:
1709
Chapter:
D
Edition:
-
Year Published:
2005
Language:
ENGLISH
Description:
16 p.
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Number of Pages:
16
Online Only (Y/N):
Y