Unnamed Occurrences (ARDF - KC170), Sylburn Harbor, Annette Island, Ketchikan Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrences (ARDF - KC170)	- not defined -
Sylburn Harbor	- not defined -
Annette Island	Island
Ketchikan Mining District	Mining District
Prince of Wales-Hyder Census Area	Census Area
Alaska	State
USA	Country

Location: This site represents six occurrences near the north base of the peninsula between Sylburn Harbor and Port Chester. The occurrences are in sections 20 and 21, T. 77 S., R. 92 E., of the Copper River Meridian. The map site is at the approximate center of this group of occurrences. The site corresponds to loc. 20a-f in Karl (1992). The location is accurate within about 0.15 mile.
Geology: The country rocks in the area of this site include recrystallized Upper Triassic carbonate and clastic rocks, rhyolite, and basalt; Silurian trondhjemite; and greenstone derived from undivided Silurian and Ordovician volcanic, sedimentary, and intrusive rocks (Berg, 1972 [I 684]; Berg and others, 1988; Karl, 1992). The rocks are folded and locally intensely sheared, sericitized, and permeated with hydrothermal hematite. The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time. The occurrences consist of quartz-barite-calcite-sulfide fissure veins as much as three feet thick, in sheared, siliceous phyllite, greenstone, rhyolite, and limestone (Karl, 1992, loc. 20a-f). Sulfide minerals, inferred from sample analyses, probably are mainly pyrite, galena, and sphalerite. Samples of sulfide-bearing quartz, calcite, and barite veins contained up to 20 ppm Ag, 2% Pb, more than 1% Zn, and 100 ppm Ni; a sample of limestone contained 1000 ppm Ba, 100 ppm Pb, and 500 ppm Zn; a sample of greenstone contained 200 ppm Zn, 100 ppm Co, 100 ppm Cr, and 100 ppm Ni; and samples of rhyolite and rhyolite tuff breccia contained up to 1 ppm Ag, 1% Ba, and 200 ppm Cu (Karl, 1992, loc. 20a-f).
Workings: Samples of sulfide-bearing quartz, calcite, and barite veins contained up to 20 ppm Ag, 2% Pb, more than 1% Zn, and 100 ppm Ni; a sample of limestone contained 1000 ppm Ba, 100 ppm Pb, and 500 ppm Zn; a sample of greenstone contained 200 ppm Zn, 100 ppm Co, 100 ppm Cr, and 100 ppm Ni; and samples of rhyolite and rhyolite tuff breccia contained up to 1 ppm Ag, 1% Ba, and 200 ppm Cu (Karl, 1992, loc. 20a-f).
Age: Fissure veins probably are Late Cretaceous or younger.
Alteration: Country rocks locally are sericitized and permeated with hydrothermal hematite.

Commodities (Major) - Ag, barite, Pb, Zn
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c)

Other Databases

Link to USGS - Alaska:	KC170

Other Regions, Features and Areas containing this locality

References