Quadrangle map, 1:250,000-scale | JU |
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Quadrangle map, 1:63,360-scale | B-3 |
Latitude | 58.2873 |
Longitude | -134.8624 |
Nearby scientific data | Find additional scientific data near this location |
Location and accuracy | The Portage prospect is at an elevation of approximately 900 feet at the head of Bear Creek, on the northeast side of Green Mountain. It is 2 miles north-northeast of Funter Bay in the SE1/4NE1/4 section 25, T. 41 S., R. 65 E. of the Copper River Meridian. The location is accurate within 1/4 mile. |
Geologic descriptionThe Portage prospect consists of lenticular quartz masses in slate that are sub-parallel to the cleavage (Cobb, 1978 [OFR 78-374]). The quartz contains disseminated pyrite, chalcopyrite, and minor galena. The prospect contained low gold values by 1900 standards (Cobb, 1978 [OFR 78-374]). Nearby, chlorite-mica schist is cut by quartz-calcite veinlets contain small masses of pyrite and chalcopyrite across a width of 30 to 40 feet (Wells and others, 1986). The deposit was discovered prior to 1906 and was explored by a small shaft, a tunnel that failed to reach the ore zone, open cuts, and trenches (Wright, 1907) The deposit in the mica schist resembles the one at the Mammoth prospect (JU248) (Cobb, 1978 [OFR 78-374]). The rocks in the area are mainly Ordovician and Devonian to Triassic clastic strata, mafic-intermediate volcanic rocks, and subordinate limestone. The bedded rocks are intruded and locally metamorphosed by Cretaceous granodiorite (Gehrels and Berg, 1994). | |
Geologic map unit | (-134.864194481273, 58.2869648810514) |
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Workings or exploration | Surface sampling, shallow shaft, tunnel, open cuts, and trenches. |
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Indication of production | None |
MRDS Number | A012114 |
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ReferencesGehrels, G.E., and Berg, H.C., 1994, Geology of southeastern Alaska, in Plafker, George, and Berg, H. C., eds., The geology of Alaska: Geological Society of America, DNAG, The geology of North America, Vol. G-1, p. 451-467.
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Reporters | J.C. Barnett and L.D. Miller (Juneau, Alaska ) |
Last report date | 12/15/2001 |