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Sample: 84-ARh-98

Sample ID: 84-ARh-98 [1]
Station ID: 84-ARh-98
AT Num:
Volcano: Sanford
Possible source:
Eruption:
Collector: Richter, D. H.
Date sampled: 1984-00-00
Sample type 1: Other
Color:
Final unit:
Text Description: Mount Sanford hypabyssal rhyolite pluton (Pleistocene). Small, massive, reddish-gray, porphyritic hornblende rhyolite associated with west Sanford eruptive center. Rock contains phenocrysts of plagioclase (5-8%, average 1 mm) and hornblende (trace to 1%, average <1 mm; locally altered), in trachyitic groundmass of plagioclase and hornblende microlites in cryptocrystalline matrix. Pluton may be ring-fracture intrusion along postulated caldera wall.
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.