Unnamed (near Portage Creek)

The Unnamed (near Portage Creek) is a gold mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Unnamed (near Portage Creek)

Commodity

Primary: Gold
Secondary: Arsenic

Location

State: Alaska
District: Yentna

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Not available

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Pyrite
Ore: Gold
Ore: Arsenopyrite
Gangue: Quartz

Comments

Comment (Workings): Workings / Exploration = Rock chip sampling and silt sampling by the U.S. Geological Survey (Reed and others, 1978) and mapping, rock chip sampling and silt sampling Cominco American Incorporated in the late 1980s have been done in the area. Reed and others (1978) describe altered granodiorite float with thin (less than 5 millimeters wide) veinlets of arsenopyrite and pyrite with up to 1.5 ppm gold. Other private companies have conducted reconnaissance programs in the area at various times between the 1960s to present.

Comment (Geology): Age = Late Cretaceous/early Tertiary; mineralization is interpreted to be related to the granodiorite of Mt. Estelle for which hornblende ages are about 65 to 66 m.y. (Reed and Nelson, 1980).

Comment (Deposit): Other Comments = Similar gold-sulfide veins are also present in the Estelle pluton, ARDF record TY019 to the south in the Tyonek quadrangle.

Comment (Geology): Geologic Description = Reed and others (1978) describe altered granodiorite float with thin (<5 millimeters wide) veinlets of arsenopyrite and pyrite with up to 1.5 ppm gold. . The occurrence lies within the Late Cretaceous /early Tertiary (65 m.y. to 66 m.y.) granodiorite of Mount Estelle (Te) that intrudes Mesozoic marine sedimentary rocks (KJs) (Reed and Nelson, 1980). At this locality the pluton has a leucocratic equigranular phase and a porphyritic phase with potassium feldspar phenocrysts up to 10 millimeters in size (Cominco American Incorporated, unpublished report). The granodiorite of Mt. Estelle probably reflects the same plutonic event as the composite plutons (Tcp) to the north described by Reed and Nelson (1980). About 2 miles N72E of this location gold-sulfide-bearing veinlets are described at an unnamed site (TL052). . Similar gold-sulfide veins are also present in the Estelle pluton, ARDF record TY019 to the south in the Tyonek quadrangle.

Comment (Reference): Primary Reference = Reed and others, 1978

Comment (Exploration): Status = Inactive

References

Reference (Deposit): Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1174, scale 1:250,000.

Reference (Deposit): Cobb, E.H., and Reed, B.L., 1980, Summaries of data and lists of reference to metallic and selected nonmetallic mineral deposits in the Talkeetna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-884, 106 p.

Reference (Deposit): Reed, B.L., Nelson, S.W., Curtin, G.C., and Singer, D.A., 1978, Mineral resources map of the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-870-D, 1 sheet, scale 1:250,000.

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