Wrangell Lava. Crystal-rich dacite flow. Light gray, locally streaked reddish-gray, massive to flow-laminated, moderately crystal rich dacite containing phenocrysts of sodic plagioclase (5-10%, 2-5 mm) that are locally resorbed, biotite (1-3%, 1-3 mm), rounded quartz (trace to 1%, 2 mm), and traces of opaque minerals in a microtrachytic groundmass. Possibly late flow from rhyolite dome (unit Qrd). K-Ar age of biotite from sample 81-ASj-72 (map locality 20) is 1.74 +/- 0.11 Ma.
Geologic map of the Nabesna B-6 Quadrangle, south-central Alaska
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