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Sample: 84-ARh-97

Sample ID: 84-ARh-97 [1]
Station ID: 84-ARh-97
AT Num:
Volcano: Sanford
Possible source:
Eruption:
Collector: Richter, D. H.
Date sampled: 1984-00-00
Sample type 1: Lava
Color:
Final unit:
Text Description: Mount Sanford Dacite flows (Pleistocene). Massive, light- to medium-light-gray, conspicuously porphyritic dacite flows on west and southeast flanks of Mount Sanford. Flow on west flank contains phenocrysts of plagioclase (4-6%, 1-2 mm), hornblende (2-3%, 1 mm; mostly altered to opaque minerals), and opaque minerals (trace), in trachytic to cryptocrystalline groundmass. Flow fills pronounced topographic low that is possibly along postulated caldera wall; maximum thickness about 500 m. Flow on southeast flank is coarsely porphyritic, containing phenocrysts of plagioclase (15-20%, as large as 1 cm), clinopyroxene (1-3%, 1-2 mm), opaque minerals (1%), and biotite (trace), in microfelty groundmass that consists chiefly of feldspar. Maximum thickness about 150 m.
Sample Location:

References Cited

[1] Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska, 1994

Richter, D. H., Duffield, W. A., Sawyer, D. A., Schmoll, H. R., and Ratte, J. C., 1994, Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska: U.S. Geological Survey Geological Quadrangle Map GQ 1728, unpaged, 1 sheet, scale 1:63,360.