Sample: 81-ASj-72

Sample ID:	81-ASj-72 ^[1]
Station ID:	81-ASj-72
AT Num:
Volcano:
Possible source:
Eruption:
Collector:	Unknown, Unknown
Date sampled:	1981-00-00
Sample type 1:	Lava
Color:
Final unit:
Text Description:	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.
Sample Location:

References Cited

[1] Geologic map of the Nabesna B-6 Quadrangle, south-central Alaska, 1993

Richter, D. H., Smith, J. G., Schmoll, H. R., and Smith, R. L., 1993, Geologic map of the Nabesna B-6 Quadrangle, south-central Alaska: U.S. Geological Survey Geological Quadrangle Map GQ 1688, unpaged, 1 sheet, scale 1:63,360.