|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||A-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents 5 occurrences along about a half-mile of the south shoreline of the west-trending peninsula that separates Sylburn Harbor from Port Chester. The occurrences are in sections 9 and 29, T. 77 S., R. 92 E., of the Copper River Meridian, between 0.5 and 0.9 mile from Driest Point. The map coordinates are for their approximate midpoint. The site corresponds to loc. 16 in Berg (1972 [I 684]), loc. 135 in Elliott and others (1978), and loc. 23a-e in Karl (1992). The location is accurate within about 0.1 mile.|
The country rocks in the area of this site are recrystallized, Upper Triassic carbonate and clastic rocks, rhyolite, and basalt (Berg, 1972). The rocks are folded and faulted, and intruded by rhyolite dikes. All were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.The mineral occurrences consist of quartz-calcite-barite(-hematite) veins up to 6 feet thick that contain galena and sphalerite, and extend at least 60 feet inland from tidewater (Karl, 1992, loc. 23). The veins are hosted by dolomitic conglomerate and brecciated rhyolite. Rhyolite dikes up to 60 feet thick cut the conglomerate and also intrude the veins. Samples of variously mineralized veins and bedded rocks contained up to 20 ppm Ag, more than 2% Pb, 1500 ppm Zn; and more than 5000 ppm Ba (Karl, 1992, loc. 23a-e).
|Geologic map unit||(-131.593679908967, 55.1706554911236)|
|Mineral deposit model||Polymetallic veins (Cox and Singer, 1986; model 22c)|
|Mineral deposit model number||22c|
|Age of mineralization||Veins hosted by Upper Triassic strata and cut by a rhyolite dike may be Late Triassic in age; veins that postdate the dike may be Late Cretaceous or younger.|
|Workings or exploration||Samples of variously mineralized veins and bedded rocks contained up to 20 ppm Ag, more than 2% Pb, 1500 ppm Zn; and more than 5000 ppm Ba (Karl, 1992, loc. 23a-e).|
|Indication of production||None|
Berg, H.C., 1972, Geologic map of Annette Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-684, 8 p., 1 sheet, scale 1:63,360.
|Reporters||H.C. Berg, USGS|
|Last report date||7/6/1999|