Sample: 87-WAD-4

Sample ID:	87-WAD-4 ^[1]
Station ID:	87-WAD-4
AT Num:
Volcano:
Possible source:
Eruption:
Collector:	Duffield, W. A.
Date sampled:	1987-00-00
Sample type 1:	Other
Color:
Final unit:
Text Description:	Nathlie Mountain hornblende dacite intrusion (Pleistocene). Yellowish-gray, massive, porphyritic dacite (fig 4) that locally displays well-developed columnar joints. Phenocrysts consist of strongly zoned (An15-55) plagioclase (7-15%, as large as 4 mm) highly altered hornblende (1-4%, as long as 3 mm), hypersthene (trace to 1%, 0.5 mm), and rare quartz in cavities, in microfelty groundmass of plagioclase and mafic, opaque, and alteration minerals.
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.

Alaska Volcano Observatory

Sample: 87-WAD-4

References Cited

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