Roosevelt Creek

Prospect, Inactive

Alternative names

RO
Skroo

Commodities and mineralogy

Main commodities Cu; Pb; Zn
Other commodities Ag; Au
Ore minerals chalcopyrite; galena; pyrite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale A-6
Latitude 67.1386
Longitude -152.9018
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is near Roosevelt Creek about two miles north of the Malamute Fork, Alatna River. A large claim group which extends about 10 miles east-west and 1 to 1.5 miles north-south, is shown by Dillon and others (1981, Plate 1); the claims are presumed to cover this this prospect. For this record, the site is about 0.5 mile east-northeast of the center of section 30, T. 27 N., R. 25 W. The location is accurate within 1 mile.

Geologic setting

Geologic description

Sparse published information about the Roosevelt Creek prospect principally cites oral communications and reports of unpublished industry data. The most recent of the published reports (Nokleberg and others, 1996) describes the Roosevelt Creek prospect as massive and disseminated(?) sulfides in metavolcanics, pelitic schists and marbles of the Devonian and Mississippian, Ambler sequence. The sulfides are described as probably chalcopyrite, sphalerite, and galena. Dillon and others (1986) map the general area of the prospect as Devonian, metavolcanic rocks and Proterozoic(?) or lower Paleozoic schists of various types, along with local marble. Grybeck (1977) indicates that the geology and geochemistry of the area is similar to that to the west in the Ambler district.
Kurtak and others (2002) examined the area during their study of the Koyukuk mining district. They report that the canyon on Roosevelt Creek exposes Devonian(?) muscovite schist, graphitic schist and metarhyolite in a sequence that trends generally east-west and dips 55o south. Drilling by Anaconda Alaska intersected narrow, discontinuous zones of massive to semi-massive pyrite, sphalerite, galena, and chalcopyrite in schist and metarhyolite.
Several rock samples collected along Roosevelt Creek in the vicinity of the presumed location of the prospect are described in Dillon and others (1981) as felsic schists or felsites, most of which contain 1-2 percent disseminated pyrite. One sample may contain as much as 3 percent disseminated chalcopyrite and another may contain galena. Chemical analysis of these samples showed that only one contained any base metals: it was weakly anomalous in Pb.
Following up a geochemical soil anomaly, industry staked claims over the prospect in 1975 (Kurtak and others, 2002. ) The prospect was explored by geophysics in 1976 and 1977. Grybeck (1977, loc. 1) reported that 77 lode claims were staked in 1975, and Dillon and others (1981) show a large claim block over the property that extended at least 10 miles east and 1 to 1.5 miles north. One of two core holes drilled in 1978 by Anaconda Alaska intersected massive-sulfide mineralization. Four more holes drilled in 1979 also intersected mineralization.
Geologic map unit (-152.904541038609, 67.1381197079863)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization Correlative with the massive-sulfide deposits in the Devonian and Mississippian Ambler Sequence.
Alteration of deposit Not specifically mentioned.

Production and reserves

Workings or exploration Based on a geochemical soil anomaly, Anaconda Alaska first staked over the prospect in 1975 ( Grybeck, 1977, Kurtak and others, 2002) The prospect was explored by geophysics in 1976 and 1977. Dillon and others (1981) show a large claim block over the property that extended at least 10 miles east-west and 1 to 1.5 miles north-south. One of two core holes drilled in 1978 by Anaconda Alaska intersected massive-sulfide mineralization. Four more holes drilled in 1979 also intersected mineralization.
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

Core samples from three drill holes from the Roosevelt Creek and/or RO prospects are stored at the Alaska Geologic Materials Center in Eagle River, Alaska.

References

References

Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska: Final Report: U.S. Bureau of Land Management Technical Report 50, v. 1 and 2, 845 p.
Reporters J.M. Britton (Anchorage); D.J. Grybeck (Contractor, USGS)
Last report date 2/1/2011