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Flanders Prospect, Eagle District, Southeast Fairbanks Borough, Alaska, USA

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The Flanders prospect is located within Doyon, Ltd. selected or conveyed land. For more information contact Doyon, Ltd., Fairbanks, Alaska.
Location: The Flanders prospect covers an area of about one-third of a square mile along lower Deep Creek, mostly on the slope and ridge west of the creek. The coordinates are the approximate center of the prospect, in the SE1/4 section 30, T. 2 N., R. 27 E., of the Fairbanks Meridian. The location is accurate. The Flanders prospect is located within Doyon, Ltd. selected or conveyed land.
Geology: The Flanders prospect is one of a northwest-trending set of ophiolite-hosted gold prospects informally referred to as the Flume trend. The Flume-trend prospects are associated with a semicontinuous, 4-mile-long soil anomaly with more than 10 ppb gold and elevated arsenic. Other lode gold prospects within the Flume trend include Flume Creek (EA009), Bonanza Creek (EA010), and Alder Creek (EA013). One-half mile to the south, and subparallel to the Flume trend, the Deep Creek trend of volcanic-hosted lode gold prospects includes the Deep Creek (EA017), and Kill Zone 2 (EA016) prospects and the Jay Creek and Kill Zone 3 gold anomalies that are defined by soil sampling. The Flume trend prospects are in weakly metamorphosed ultramafic, mafic, and oceanic sedimentary rocks of the Seventymile terrane (Foster and others, 1985). Rocks of the Seventymile terrane are deformed and cut by internal thrust faults. These rocks are juxtaposed with Paleozoic metamorphic rocks to the north and south along northwest-trending strands of the Tintina strike-slip fault. Bimodal Tertiary(?) dikes, including porphyritic rhyolite and diorite-gabbro, intrude older rocks. The Flanders prospect is in black aphanitic to fine-grained to porphyritic basalt, volcanic breccia, agglomerate, and minor chert and tuff (WGM Inc., 2001). These units are cut by a set of sub-parallel quartz-carbonate zones containing gold; the zones were subsequently cut by later high-angle faults. The quartz veins are localized along tabular tension fractures that dip north at 30 to 45 degrees (WGM Inc., 1998 [DLR 98-19]). Quartz veins exposed in trenches are broken and sheared and range from 1 inch to greater than 4 feet wide. Veins show multiple generations of bull, comb, breccia in-fill, and ribbon-quartz textures. Sulfides and visible gold are found in the quartz veins, silica-carbonate vein selvages, and in narrow silica-carbonate alteration zones. Sulfides include visible arsenopyrite, pyrite, and trace galena and microscopic sphalerite and chalcopyrite. The gold grains are 5 to 150 microns in diameter and some have sulfide inclusions. Wall-rock alteration includes propylitic, silica-carbonate with mariposite, sericitic, argillic, and albitic types. Hydrothermal white mica from wall rocks that border a gold-bearing quartz-arsenopyrite vein at the nearby Flume Creek prospect (EA009) gives a 40Ar/39Ar plateau age of 100 +/- 3 Ma, interpreted to be the age of gold deposition (Newberry and others, 1996). Geologic similarities between the two prospects suggest the Flanders prospect may be the same age. The Flanders prospect is a high-grade gold target with the potential for several million tons of material that grades 0.5 ounce of gold per ton in quartz veins and zones of quartz-carbonate alteration (WGM Inc., 1998 [DLR 98-19]). Central Alaska Gold Co. calculated an inferred resource at the Flanders prospect of 275,000 tons of material with an average grade of 0.8 ounce of gold per ton, on the basis of limited drilling and trenching (WGM Inc., 1998 [DLR 98-19]). Core holes drilled by Central Alaska Gold Co. in the early 1990's intercepted 28.5 feet with 0.29 ounce of gold per ton. One high-grade interval 3 feet long has 1.63 ounces of gold per ton; another 5 feet long has 0.59 ounce of gold per ton. The core holes drilled by Central Alaska Gold Co. were located west of the widest part of the soil geochemistry anomaly that coincides with the deposit (WGM Inc., 2000 [Seventymile property summary]). Intercepts in core holes drilled by WGM Inc. in 2000 include 16 feet with 0.25 ounce of gold per ton, 11 feet with 0.11 ounce of gold per ton, and 3.6 feet with 6.01 ounces of gold per ton (Szumigala and others, 2001). Trench samples include one 3.5-foot-long interval with 3.27 ounces of gold per ton (WGM Inc., 1998 [DLR 98-19]). Soil surveys indicate that anomalies of as much as 280 ppb gold coincide with crystal lithic tuff. A strong magnetic anomaly coincides with basaltic and serpentinite host rocks. There is an arsenic anomaly that coincides with gold values east and west of Deep Creek. Reconnaissance exploration by WGM Inc. in the mid-1970s identified several mineral targets in the Seventymile region (WGM Inc., 1998 [DLR 98-19]). In 1989 and 1990, Central Alaska Gold Co. explored the Flume Creek (EA009) and Deep Creek (EA017) areas. The Flanders prospect was discovered in 1990, and 11 core holes were drilled. In 1996, WGM Inc. expanded soil sampling at the Flanders and Deep Creek prospects, conducted ridgetop, sampling along a 13-mile segment between the Crooked Creek trend and Flume and Deep Creek trends, and had an airborne geophysical survey flown over the Flume, Deep Creek, and Crooked Creek trends. In 2000, 3,429 feet of core was drilled (Szumigala and others, 2001).
Workings: Reconnaissance exploration by WGM Inc. in the mid-1970s identified several mineral targets in the Seventymile region (WGM Inc., 1998 [DLR 98-19]). In 1989 and 1990, Central Alaska Gold Co. explored the Flume Creek (EA009) and Deep Creek (EA017) areas. The Flanders prospect was discovered in 1990, and 11 core holes were drilled. In 1996, WGM Inc. expanded soil sampling at the Flanders and Deep Creek (EA017) prospects, conducted ridgetop sampling along a 13-mile segment between the Crooked Creek trend and Flume and Deep Creek trends, and had an airborne geophysical survey flown over the Flume, Deep Creek, and Crooked Creek trends. In 2000, 3,429 feet of core was drilled (Szumigala and others, 2001). Core holes drilled by Central Alaska Gold Co. in the early 1990's intercepted 28.5 feet with 0.29 ounce of gold per ton. One high-grade interval 3 feet long has 1.63 ounces of gold per ton; another 5 feet long has 0.59 ounce of gold per ton. The core holes drilled by Central Alaska Gold Co. were located west of the widest part of the soil geochemistry anomaly that coincides with the deposit (WGM Inc., 2000 [Seventymile property summary]). Intercepts in core holes drilled by WGM Inc. in 2000 include 16 feet with 0.25 ounce of gold per ton, 11 feet with 0.11 ounce of gold per ton, and 3.6 feet with 6.01 ounces of gold per ton (WGM Inc., 2001). Trench samples include one 3.5 -foot-long interval with 3.27 ounces of gold per ton (WGM Inc., 1998 [DLR 98-19]). Soil surveys indicate that anomalies of as much as 280 ppb gold coincide with crystal lithic tuff. A strong magnetic anomaly coincides with basaltic and serpentinite host rocks. There is an arsenic anomaly that coincides with gold values east and west of Deep Creek.
Age: Dating by 40Ar/39Ar of hydrothermal mica from the margin of a gold-bearing quartz-arsenopyrite vein at the Flume Creek (EA009) prospect nearby gives a plateau age of 100 +/- 3 Ma. This is probably age of gold deposition (Newberry and others, 1996).
Alteration: Wall-rock alteration types include propylitic, silica-carbonate with mariposite, sericitic, argillic, and albitic.
Reserves: The Flanders prospect is a high-grade gold target with the potential for several million tons of material that grades 0.5 ounce of gold per ton in quartz veins and zones of quartz-carbonate alteration (WGM Inc., 1998 [DLR 98-19]). Central Alaska Gold Co. calculated an inferred resource at the Flanders prospect of 275,000 tons of material with an average grade of 0.8 ounce of gold per ton, on the basis of limited drilling and trenching (WGM Inc., 1998 [DLR 98-19]).

Commodities (Major) - Au; (Minor) - As, Cu, Pb, Zn
Development Status: None
Deposit Model: Listwaenite (altered ophiolite) gold (Newberry and others, 1998).

Mineral List



14 entries listed. 11 valid minerals.

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References

Clark, S.H.B., and Foster, H.L., 1971, Geochemical and geological reconnaissance in the Seventymile River area, Alaska: U.S. Geological Survey Bulletin 1315, 21 p. Foster, H.L., Cushing, G. W., Keith, T. E. C., and Laird, J., 1985, Early Mesozoic tectonic history of the Boundary area, east-central Alaska: Geophysical Research Letters, v. 12, p. 553-556. Keith, T.E., Foster, H.L., Foster, R.L., Post, E.V., and Lehmbeck, W.L., 1981, Geology of an alpine-type peridotite in the Mt. Sorenson area, east-central Alaska: U.S. Geological Survey Professional Paper 1170-A, p. A1-A9. Newberry, R.J., Layer, P.W., Burleigh, R.E., and Solie, D.N., 1996, New 40Ar/39Ar dates for intrusions and mineral prospects in the eastern Yukon-Tanana terrane, Alaska - Regional patterns and significance, in Gray, J.E., and Riehle, J.R., eds., Geological Studies in Alaska by the U.S. Geological Survey, 1996: U.S. Geological Survey Professional Paper 1595, p. 131-159. Rogers, Bob, and Bradley, Laura, 1998, Gold deposits of the Seventymile Belt: Extended Abstracts of the 16th Biennial Conference on Alaskan Mining, Second Rush of 98; Alaska Miners Association meeting March 2-7, 1998, Fairbanks, Alaska, p. 22. Szumigala, D.J., Swainbank, R.C., Henning, M.W., and Pillifant, F.M., 2001, Alaska's mineral industry 2000: Alaska Division of Geological and Geophysical Surveys Special Report 55, 66 p. WGM Inc., 1998, Ventures Resource Alaska projects, 1997 progress report, Seventymile property exploration, volume 1: Doyon, Ltd. Report 98-19. (Report held by Doyon, Ltd., Fairbanks, Alaska). WGM Inc., 2000, Seventymile property summary, in Ventures Resource Alaska project overview and properties summary: Ventures Resource Corporation report.

 
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