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Sample: 96-Mc-5

Sample ID: 96-Mc-5 [1] [2]
Station ID: 96-Mc-5
AT Num:
Volcano: Akutan
Possible source:
Eruption:
Collector: McGimsey, R. G.
Date sampled: 1996-00-00
Sample type 1: Lava
Color:
Final unit: aau
Text Description: QTd - Extrusive rocks (Pleistocene and Pliocene). Domes or massive flows generally associated with small subaqueous cinder cones (QTc). Rocks exhibit spectacular columnar joints. They are greenish black to medium gray, porphyritic basalts (50.3-51.6% SiO2) containing phenocrysts of plagioclase (5-15%, 3-4 mm), clinopyroxene (1-10% 2-3 mm), and olivine (trace-3%, 1-2 mm) in a pilotaxitic groundmass. Whole rock 40Ar/39Ar mean age of the basalt is 1.55+/-0.04 Ma.
Sample Location:

References Cited

[1] Geology of Akutan Island, Alaska, 1998

Richter, D. H., Waythomas, C. F., McGimsey, R. G., and Stelling, P. L., 1998, Geology of Akutan Island, Alaska: U.S. Geological Survey Open-File Report 98-0135, 22 p., 1 sheet, scale 1:48,000.

[2] The eruptive history, magmatic evolution, and influence of glacial ice at long-lived Akutan volcano, eastern Aleutian Islands, Alaska, 2020

Coombs, M.L., and Jicha, B.R., 2020, The eruptive history, magmatic evolution, and influence of glacial ice at long-lived Akutan volcano, eastern Aleutian Islands, Alaska: GSA Bulletin, 29 p., https://doi.org/10.1130/B35667.1.