Unassigned rocks, older rhyolite dome (Pleistocene). Pinkish-gray, sparsely porphyritic rhyolite that contains 1-2% phenocrysts of plagioclase, opaque minerals, and possibly some altered mafic minerals, in microfelty groundmass of feldspar. Only exposed in one locality near northwest corner of quadrangle. * * * Whole-rock K-Ar age is 1.23+/-0.07 Ma.
Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska
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