|Quadrangle map, 1:250,000-scale||PE|
|Quadrangle map, 1:63,360-scale||B-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The North Marsha Peak prospect is about 0.5 mile north of Marsha Peak and about 0.4 mile east of the center of section 18, T. 62 S., R. 86 E. The location is accurate. A map of the prospect is Figure 30 of Still and others (2002).|
The rocks in the prospect area are part of a belt of Mesozoic or Paleozoic sedimentary and volcanic rocks that have been metamorphosed to Tertiary or Cretaceous schist and gneiss. The belt is about 1 1/2 mile wide and strikes northwest (Brew, 1997; George and Wyckoff, 1973). The metamorphic rocks are bounded on the east by a thick, regionally extensive, 60 to 70 Ma tonalite sill and on the west by a 90 Ma granodiorite pluton (Brew, 1997 Still and others, 2002). On the north side of Groundhog Basin, about 2 miles northwest of this prospect, the metamorphic rocks are intruded by a 16.3 Ma biotite 'tin' granite pluton about 1,000 by 2,0000 feet in size. The granite is probably the source of the numerous rhyolite dikes and sills that extend from it and the mineralization in the area (Newberry and Brew, 1989).
The mineralization at this prospect was described by Gault and others (1953) but little was done on it by industry until the property was optioned by the Bunker Mill Mining Company in 1965. From 1968 to 1970, Humble Oil and Refining Company optioned the property and drilled two holes on it through the Nelson Glacier. El Paso Natural Gas Company optioned the property from 1971 to 1973, collected numerous surface samples, and drilled three holes on it, 116 to 230 feet long (George and Wyckoff, 1973). Still and others (2002) re-examined the property during a mineral assessment of the area by the BLM.The mineralization here is generally similar to that in Groundhog Basin (PR040) several miles to the north and probably shares the same origin. Here the mineralization is associated with two sheared zones that parallel the foliation of the gneiss and the rhyolite sills in the gneiss; the fault zones strike north and are about 750 feet apart. As reported by Still and others (2002) the western shear zone is 4 to 12 feet thick and about 1,100 feet long. Samples averaged 1.5 ounces of silver per ton, 0.3 percent copper, 0.22 percent lead, and 0.58 percent zinc. The eastern shear zone is about 4 feet thick and can be traced for about 600 feet to where it disappears under the Nelson Glacier. Select samples of thin veinlets along the shear zone contained up to 20.7 ounces of silver per ton, 70 percent lead, and 22 percent zinc. One hole by El Paso Natural Gas Company in the western zone was probably drilled parallel to the mineralized shear zone; it averaged 1.1 percent zinc and 0.25 percent lead over its entire 116 foot length. Another drill hole in the eastern shear zone had a 13-foot interval that averaged 0.87 ounce of silver per ton, 0.08 percent copper, 0.6 percent lead, and 4.3 percent zinc.
|Geologic map unit||(-132.045481696577, 56.4930658788199)|
|Mineral deposit model||Banded Ag-Cu-Sn-Pb-Zn tabular replacement bodies, veins, and stringers.|
|Age of mineralization||Probably 16.3 Ma based on a genetic tie to a nearby, zinnwaldite 'tin' granite (Newberry and Brew, 1989).|
|Alteration of deposit||None specifically noted.|
|Workings or exploration||The mineralization at this prospect was described by Gault and others (1953) but little was done on it by industry until the property was optioned by the Bunker Mill Mining Company in 1965. From 1968 to 1970, Humble Oil and Refining Company optioned the property and drilled two holes on it through the Nelson Glacier. El Paso Natural Gas Company optioned the property from 1971 to 1973, collected numerous surface samples, and drilled three holes on it, 116 to 230 feet long (George and Wyckoff, 1973). Still and others (2002) re-examined the property during a mineral assessment of the area by the BLM.|
|Indication of production||None|
Additional commentsNo claims were active as of 2002 according to Still and others.
Brew, D.A., 1997, Reconnaissance geologic map of the Petersburg C-1 Quadrangle, Southeastern Alaska: U.S. Geological Survey Open-File Report 97-156-H, 23 p., 1 sheet, scale 1:63,360.
Gault, H.R., Rossman, D.L., Flint, G.M., Jr., and Ray, R.G., 1953, Some lead-zinc deposits of the Wrangell district, Alaska: U.S. Geological Survey Bulletin 998-B, p. 15-58.
George, R.H., and Wyckoff, B.S., 1973, Whistlepig mineral exploration program, Alaska, Final report 1972 (with attached diamond drill hole logs and analyses): Unpublished El Paso National Gas Company report 109 p. 12 sheets (available at the Bureau of Land Management, Minerals Information Center, Juneau Alaska).
Newberry, R.J., and Brew, D.A., 1989, Epigenetic hydrothermal origin of the Groundhog Basin-Glacier Basin silver-tin-lead-zinc deposits, southeastern Alaska: U.S. Geological Survey Bulletin 1903, p. 113-121.3
Still, J.C., Bittenbender, P.E., Bean, K.W., and Gensler, E.G., 2002, Mineral assessment of the Stikine area, central southeast Alaska: Bureau of Land Management Technical Report 51, 560 p.
|Reporters||D.J. Grybeck (Port Ludlow, WA)|
|Last report date||3/4/2008|