Lead Creek Prospect, Fortymile District, Bethel Borough, Alaska, USA

The Lead Creek prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: The Lead Creek prospect is located in the headwaters of Lead Creek, about 8 miles west-northwest of Liberty on the Taylor Highway. Lead Creek is not labeled on the U.S. Geological Survey topographic map of the Eagle C-1 quadrangle (1956). The coordinates are the approximate center of the 4-square-mile prospect area, located in the southwest corner of section 36, T. 4 S., R. 31 E., of the Fairbanks Meridian. The location is accurate. The hills around the head of Lead Creek (none named on the Eagle C-1 map) are, clockwise from west to east: Wizard Hill, Paradox Hill, Nodular Knob, Pebble Dike Hill, and Macarena Hill. Argent Creek is a small, west-flowing creek in the draw near the middle of section 5, T. 5 S., R. 32 E. between Pebble Dike Hill and Macarena Hill. The Lead Creek prospect is on Doyon, Ltd. selected or conveyed land.
Geology: Rocks in the vicinity of the Lead Creek prospect include carbonaceous quartz-mica schist and phyllite; weakly metamorphosed silicified volcanic rocks, quartzite, marble, and metachert; unmetamorphosed limestone, sandstone, argillite, and tuff; slightly metamorphosed greenstone, basalt, and pillow basalt; and serpentinite (WGM Inc., 1998 [DLR 98-12]). The protolith ages for these rocks may be Triassic, Permian, or Mississippian and Devonian (Dusel-Bacon and others, 1998); they are tentatively correlated with Paleozoic rocks that host stratiform lead-zinc-silver deposits in the Yukon Territory. Granodiorite, diorite, and dacite intrusions of Tertiary to Mesozoic age also occur in the Lead Creek area. The models proposed for the Lead Creek prospect include: lead-zinc stratiform massive sulfide (Schmidt, 1997); manto replacement silver-lead-zinc; breccia-hosted silver-lead-zinc; skarn-hosted lead-zinc-silver; pluton-hosted lead-zinc-copper-silver; or another type of deposit indicated by precious and base metals in siliceous nodules (WGM Inc., 1998 [DLR 98-12]). The prospect is defined by anomalous lead in soils over a 3-mile by 1.5-mile area. The mineralized system may be more extensive than indicated by soil sampling since favorable ore intervals pass under overlying units on the ridges (WGM Inc., 2000 [Champion property summary]). Graphitic quartz-mica schist and phyllite crop out on top of Paradox Hill and Nodular Knob (WGM Inc., 1998 [DLR 98-12]). A strongly graphitic schist east of Nodular Knob contains siliceous nodules and iron(?) oxide-cemented concretions that are anomalous in precious and base metals. The graphitic schist and phyllite grade into, or are in fault contact with, underlying silicified volcanic rocks. A steeply dipping, east-southeast-trending fault separates the silicified metavolcanic rocks on Nodular Knob from limestone on Pebble Dike Hill (WGM Inc., 1998 [DLR 98-12]). Sections of impure massive limestone were intersected in drill holes on the west side of Pebble Dike Hill. The limestone has been bleached, silicified, brecciated, and mineralized; it has a trace to greater than 20 percent combined pyrite, galena, and sphalerite. A carbonaceous sequence of interlayered limestone, shale, argillite, siltstone, and sandstone underlies the massive limestones. Massive sulfides (50 percent or more galena, pyrite, and sphalerite) are present in strata-bound layers within the carbonaceous sedimentary rocks. Pillow basalts form prominent outcrops on the west side of Macarena Hill and are present northwest of Paradox Hill and in drill core. Small granodiorite and quartz diorite bodies and numerous andesite, dacite, and feldspar porphyry dikes are scattered throughout the upper basin of Lead Creek (WGM Inc., 1998 [DLR 98-12]). Many of these intrusions are argillically altered, fractured, and sheared; the feldspar is altered to clays, and chlorite occurs along cleavage planes. Galena and sphalerite are sparsely disseminated in granodiorite in a drill hole on Wizard Hill. Fine-grained hornfels and skarn zones in limestone units contain garnet, wollastonite, and pyroxene. Skarns are generally small and spatially related to dikes and (or) sills. A 120-foot-thick intercept of hydrofracture breccia with greater than 25 percent disseminated pyrite that occurs in a drill hole on Pebble Dike Hill is possibly intrusion-related. A pebble dike cuts across limestone on Pebble Dike Hill. Structural features at the Lead Creek prospect include Triassic to Jurassic thrust faults, folds, and later, north-south-trending and east-southeast-trending high-angle faults (WGM Inc., 1998 [DLR 98-12]). Airborne geophysical data indicate that Lead Creek is on the periphery of a semicircular magnetic zone that contains the Champion II (EA049), North Champion (EA046), East Champion (EA047), and Little Champion Creek (EA051) prospects. An arcuate trend of high conductivity follows topographic contours around the Lead Creek basin, possibly indicating a graphitic unit with the potential for stratiform sulfide mineralization (WGM Inc., 1998 [DLR 98-12]). Sulfides at Lead Creek predominantly are galena, sphalerite, and pyrite, with trace chalcopyrite (WGM Inc., 1998 [DLR 98-12]). Sphalerite is typically reddish and coarse grained. Silver is closely associated with galena. Pyrite is the most widespread and abundant sulfide, and is present in all rock types. Silicification accompanies much of the sulfide mineralization and is especially strong in mineralized limestone. Carbonate alteration is marked by dolomite-ankerite and possibly siderite; the carbonates are primarily found in veins and breccia matrix. There are four main target areas at the Lead Creek prospect: Nodular Knob, Argent Creek, Wizard Hill, and Paradox Hill (WGM Inc., 1998 [DLR 98-12]). Siliceous nodules and scorodite-cemented nodules in graphitic schist and phyllite immediately east of Nodular Knob are anomalous in gold, silver, lead, zinc, arsenic, antimony, cadmium, mercury, and bismuth. One nodule contains 2,000 parts per billion (ppb) gold, 31.4 parts per million silver, greater than 10,000 ppm arsenic, 6 ppm bismuth, 374 ppm antimony, 1,330 ppm copper, 2.82 percent lead, and 744 ppm zinc. In the Argent Creek area, drilling intersected a stratiform massive sulfide horizon; a 47-foot interval averages 1.4 percent lead, 1.3 percent zinc, and 1.53 ounces of silver per ton (WGM Inc., 1998 [DLR 98-12]). Base metals and abundant pyrite occur in brecciated and sheared carbonaceous shale, argillite, and gray limestone, and are also found as semi-massive replacements of graywacke. Another drill hole (LC-14) in the Argent Creek area has a 31.5 foot intercept with 23.3 ounces of silver per ton and 6.4 percent lead. The Argent Creek fault has been identified as a possible ore control (Ventures Resource Corp., 2001). Quartz-vein float with iron and manganese oxides and sparse galena was found in sandstone and limestone north of Argent Creek; the float contains 2,500 ppm lead, 4,800 ppm zinc, and 1.8 ppm silver. A weakly developed skarn is exposed on Pebble Dike Hill. Step-out hole LC-15, drilled 430 feet to the southeast of 2000 hole LC-14, has a 50.6 foot intersect with 11.9 ounces of silver per ton, 5.1 percent lead, and 0.2 percent zinc in the same zone as hole LC-14. Mineralization is open west of hole LC-14; other 2001 holes tentatively indicate that it is to the east (Swainbank and others, 2002; Ventures Resource Corp., 2002). Paradox Hill contains complex, siliceous, metavolcanic breccias with clasts of quartzite, limestone, siltstone, claystone, basalt, and tuffaceous material (WGM Inc., 1998 [DLR 98-12]). Galena and sphalerite are disseminated in the quartzite clasts and occur as replacements and open-space fillings in silicified breccia matrix and in quartz-carbonate veins. The veins contain as much as 2.82 percent lead, 2.84 percent zinc, and 0.79 ounce of silver per ton. A small amount of sulfide-bearing skarn is also present in core. At Wizard Hill, sparse pyrite, galena, sphalerite, and chalcopyrite are associated with quartz-carbonate veins in quartzite and graphitic schist. Altered granodiorite contains minor disseminated pyrite, chalcopyrite, galena, and sphalerite (WGM Inc., 1998 [DLR 98-12]). The Lead Creek prospect was originally identified by stream-sediment sampling conducted by the Alaska Division of Mines and Minerals in 1968 (Smith, 1968). Argentiferous galena float was found on the ridge south of Champion Creek (the west end of Wizard Hill) in 1968 (Foster and Clark, 1970). In 1976, WGM Inc. conducted stream-sediment and soil sampling in the Lead Creek area (WGM Inc., 1998 [DLR 98-12]). In 1977 and 1978, WGM Inc. conducted soil sampling and gridded geophysical surveys, and drilled about 600 feet of core in three holes. Three EM conductors were identified during a 13.3-mile vertical-loop survey. Analyses of soil, stream-sediment, pan-concentrate, and rock samples from the Lead Creek area are reported in Burleigh and Lear (1994). In 1996, WGM Inc. carried out a mapping and sampling program at Lead Creek and identified new drilling targets. In 1997, WGM Inc. followed up an airborne EM-magnetics survey, carried out geologic mapping and sampling, and drilled a total of 3,853 feet in seven core holes. WGM Inc. drilled an additional 2,033 feet at Lead Creek in 2000 and 5,464 feet in 2001 and reported high-grade silver-lead mineralization (Ventures Resource Corp., 2001; Ventures Resource Corp., 2002). As of May 2006, the Lead Creek prospect was being examined by Full Metal Minerals under an agreement with Doyon Limited (Full Metal Minerals, 2008, 40 mile). Full Metals web site shows the location of the 22 drill holes on the property and the footages of the mineralized intercepts in them (Full Metal Minerals, 2008, Lead Creek).
Workings: The Lead Creek prospect was originally identified by stream-sediment sampling conducted by the Alaska Division of Mines and Minerals in 1968 (Smith, 1968). Argentiferous galena float was found on the ridge south of Champion Creek (the west end of Wizard Hill) in 1968 (Foster and Clark, 1970). In 1976, WGM Inc. conducted stream-sediment and soil sampling in the Lead Creek area (WGM Inc., 1998 [DLR 98-12]). In 1977 and 1978, WGM Inc. conducted soil sampling and gridded geophysics surveys and drilled about 600 feet of core in three holes at the prospect. Three EM conductors were identified during a 13.3-mile vertical-loop survey. Analyses of soil, stream -sediment, pan-concentrate, and rock samples from the Lead Creek area are reported in Burleigh and Lear (1994). In 1996, WGM Inc. carried out a mapping and sampling program at Lead Creek and identified new drilling targets. In 1997, WGM Inc. followed up an airborne EM-magnetics survey, carried out geologic mapping and sampling, and drilled a total of 3,853 feet in seven core holes. WGM Inc. drilled an additional 2,033 feet at Lead Creek in 2000 and 5,464 feet in 2001 (Ventures Resource Corp., 2001; Swainbank and others, 2002. As of May 2006, the Lead Creek prospect was being examined by Full Metal Minerals under an agreement with Doyon Limited (Full Metal Minerals, 2008, 40 mile). The Full Metals web site shows the location of the 22 drill holes on the property and the footages of the mineralized intercepts in them (Full Metal Minerals, 2008, Lead Creek).
Age: Probably Mesozoic, as inferred from the presence of skarns adjacent to Mesozoic intrusions and a Cretaceous common lead age from galena (Dusel-Bacon and others, in press [in 2003]).
Alteration: Some limestones are bleached, silicified, brecciated, and (or) contain weak skarn alteration (WGM Inc., 1998 [DLR 98-12]). Metavolcanic rocks are locally silicified and altered to clay, but the relationship of alteration to mineralization is unclear. Granodiorite porphyry is argillically altered and contains green chlorite along fractures. Many intrusions are argillically altered, fractured, and sheared, with feldspars altered to clays; chlorite occurs along cleavages.
Reserves: None.

Commodities (Major) - Ag, Pb, Zn; (Minor) - As, Au, Bi, Cd, Cu, Hg, Sb
Development Status: None
Deposit Model: Possibly Zn-Pb skarn, polymetallic replacement, or sedimentary exhalative (Cox

Mineral List

14 entries listed. 10 valid minerals.

References