|Quadrangle map, 1:250,000-scale||DE|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents two geologically similar occurrences along the west shoreline of Nichols Bay about 1.6 and 2.0 miles north-northwest of Point Nunez. One is near the center of section 4, T. 83 S., R. 89 E. The other, at the coordinates, is about at the center of the north boundary of the same section.|
Geologic descriptionThis site, first described by Gehrels and others (1983), represents two occurrences, about a half mile apart, in Silurian or Ordovician (Descon Formation) strata (Gehrels, 1992). The northern occurrence consists of several centimeter-thick, pyrite-rich layers in fragmental silicic volcanic rocks. Samples contained up to 0.5 parts per million (ppm) silver and 140 ppm zinc. The 10-meter-wide unit that contains the pyrite-rich layers may extend to the southern occurrence. The southern occurrence consists of several 2- to 6-centimeter-thick lenses that contain much pyrite and microscopic sphalerite, in locally fragmental, silicic volcanic rocks. The mineralized rock is interbedded with andesitic pillow breccia and massive flows; andesite dikes cut the mineralized lenses. Samples contained up to 0.7 ppm silver and 140 ppm zinc.
|Geologic map unit||(-132.124463809436, 54.7067616112902)|
|Mineral deposit model||Kuroko massive sulfide (Cox and Singer, 1986; model 28a).|
|Mineral deposit model number||28a|
|Age of mineralization||The massive-sulfide layers are contemporaneous with the deposition of the Silurian or Ordovician Descon Formation.|
|Workings or exploration||Only outcrop sampling.|
|Indication of production||None|
Gehrels, G. E., 1992, Geologic map of southern Prince of Wales Island, southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-2169, 23 p., 1 sheet, scale 1:63,360.
|Reporters||D.J. Grybeck (Applied Geology)|
|Last report date||9/1/2003|