|Quadrangle map, 1:250,000-scale||JU|
|Quadrangle map, 1:63,360-scale||B-3|
|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.|
The 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)|
|Workings or exploration||Surface sampling, shallow shaft, tunnel, open cuts, and trenches.|
|Indication of production||None|
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Juneau quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-374, 155 p.
Gehrels, 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.
Wells, D.E., Pittman, T.L., Brew, D.A. and Douglass, S.L., 1986, Map and description of the mineral deposits in the Juneau, Taku River, Atlin, and part of the Skagway quadrangles, Alaska: U.S. Geological Survey Open-File Report 85-717, 332 p., 1 sheet, scale 1:250,000.
|Reporters||J.C. Barnett and L.D. Miller (Juneau, Alaska )|
|Last report date||12/15/2001|