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Sample: 96-Mc-31B

Sample ID: 96-Mc-31B [1] [2]
Station ID: 96-Mc-31B
AT Num:
Volcano: Akutan
Possible source:
Eruption:
Collector: McGimsey, R. G.
Date sampled: 1996-00-00
Sample type 1: Lava
Color: gray
Final unit: bef
Text Description: Qfl - Flat Top lava flows. Thin (2 m) to medium (6 m) (at distal ends) lava flows exhibiting conspicuous reddish, oxidized scoriaceous tops and bottoms. Rocks are medium gray to medium dark gray porphyritic basalts (50.3 - 51.3% SiO2) containing phenocrysts of plagioclase (10-20%, 3 mm), olivine (2-6%, 1-2 mm), and clinopyroxene (trace=3%, 0.5-1 mm) in an intergranular groundmass. Whole rock 40Ar/39Ar mean age of basalt is 0.25 +/- 0.04 Ma. Unit as mapped may include flows from both present Akutan Volcano and ancestral Akutan.
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.