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Mafic Knob 500 description and information

MAFIC KNOB 500 LINKS

SAMPLES
LOCATION
FACTS
Type:Post-glacial mafic lava mesa; possible flank vent for Peulik (Hildreth and others, 2007),
Most Recent Activity:
Seismically Monitored: No
Elevation: 0 ft ( m)
Latitude: 57.82344° N
Longitude:156.42616° W
Quadrangle:Ugashik
CAVW Number:
Nearby towns:Kanatak 23 mi (37 km) SE
Ugashik 42 mi (67 km) SW
Egegik 44 mi (71 km) NW
Pilot Point 46 mi (74 km) SW
Anchorage 327 mi (526 km) NE
DESCRIPTION
From Hildreth and others (2007) [1]: "About 5 km east of Ukinrek Maars, a circular mesa of postglacial mafic lava (53.6-54.1 weight percent SiO2), ~1 km in diameter, stands 100 m above a surrounding hummocky lowland that consists of lake deposits and a debris-avalanche sheet derived from the Ugashik-Peulik edifice. The rugged surface of the mesa, corrugated by several pressure ridges, has not been overridden by either ice or avalanche, and the lava appears to have welled up in place and spread out locally, as if confined. The unit is compositionally similar to the postglacial lava flows that make up the cone and apron of Mount Peulik [2], but is distinguishable from all other units in the district. This enigmatic exposure may represent an authentic flank vent for Peulik magma, or, conceivably, a rootless secondary vent for invasive lava that had burrowed beneath the avalanche deposit."
REFERENCES CITED
[1]
Blue Mountain and The Gas Rocks: rear-arc dome clusters on the Alaska Peninsula, 2007
citation imageHildreth, Wes, Fierstein, Judy, and Calvert, A.T., 2007, Blue Mountain and The Gas Rocks; rear-arc dome clusters on the Alaska Peninsula: in Haeussler, P.J., and Galloway, J.P., eds., Studies by the U.S. Geological Survey in Alaska, U.S. Geological Survey Professional Paper 1739-A, 27 p., available at http://pubs.usgs.gov/pp/pp1739/a/ .
Download USGS website with link to full-text PDF

[2]
Geology of the Ugashik-Mount Peulik volcanic center, Alaska, 2004
citation imageMiller, T. P., 2004, Geology of the Ugashik-Mount Peulik volcanic center, Alaska: U.S. Geological Survey Open-File Report OF 2004-1009, 19 p., 2 sheets, scale 1:63,360.
Download website with links to PDFs
Download PDF full-text PDF : 1.7 MB
Download PDF plate 1 PDF : 660 KB
Download PDF plate 2 PDF : 142 KB

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Page modified: March 2, 2017 15:59
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