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Sample: 87-ARh-26

Sample ID: 87-ARh-26 [1]
Station ID: 87-ARh-26
AT Num:
Volcano:
Possible source:
Eruption:
Collector: Richter, D. H.
Date sampled: 1987-00-00
Sample type 1: Lava
Color:
Final unit:
Text Description: Unassigned rocks, andesite flows and dikes (Pleistocene). Flows, 5-15 m thick, are medium-gray, sparsely porphyritic andesite that contains about equal amounts (1-3%) of small (1 mm) phenocrysts of plagioclase, hypersthene, clinopyroxene, and possibly hornblende, in pilotaxitic groundmass. Some small areas of two-pyroxene andesite flows (Qwa) from the summit area of Wrangell may be locally present in this unit. All dark dikes south of Dadina River-Glacier system are included in unit; those that were examined are dark-gray, sparsely porphyritic hypersthene andesite and two-pyroxene andesite. Flows apparently erupted from fissures such as one filled by east-west-trending andesite dike (secs. 26 and 27, T. 3 N., R. 5 E.); earliest flows are interbedded with uppermost conglomerate beds of unit Qcg.
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.