Radiometric age of the Monograptus cyphus graptolite zone in Southeastern Alaska — an estimate of the age of the Ordovician—Silurian boundary
- 1 January 1977
- journal article
- research article
- Published by Cambridge University Press (CUP) in Geological Magazine
- Vol. 114 (1) , 15-24
- https://doi.org/10.1017/s0016756800043387
Abstract
Summary: K—Ar age measurements on Esquibel Island, southeastern Alaska yield a minimum age of about 433±3 Ma for the Zone of Monograptus cyphus of the Lower Silurian. An age of approximately 435—437 Ma is estimated for the Ordovician—Silurian boundary.This publication has 18 references indexed in Scilit:
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