Shamrock Creek; VABM Buck Prospects, Fairbanks Mining District, Fairbanks North Star Borough, Alaska, USAi

Regional Level Types
Shamrock Creek; VABM Buck Prospects	Group of Prospects
Fairbanks Mining District	Mining District
Fairbanks North Star Borough	Borough
Alaska	State
USA	Country

Location: Shamrock Creek is a lode prospect located on the southwest side of VABM Buck, approximately 7 miles northwest of the town of Richardson, Alaska, on the Richardson Highway. There are numerous prospecting trenches in the area southwest of VABM Buck. The approximate center of prospecting is in NW1/4NW1/4 section 29, T. 6 S., R. 6 E., of the Fairbanks Meridian. Shamrock Creek can be accessed from an unimproved road in the Redmond Creek drainage. It was not identified as a separate location by Cobb (1972) or by Cobb and Eberlein (1980).
Geology: The Richardson area is characterized by gentle slopes and broad, alluvium-filled valleys (Prindle and Katz, 1913, p. 140). The area is unglaciated and largely overlain by windblown silt, sand, and loess, locally up to 50 meters thick (Foster and others, 1979). The bedrock in the region comprises greenschist to amphibolite facies schist, marble, and gneiss that have been intruded by various igneous bodies (Bundtzen and Reger, 1977, p. 29). The schist and marble are probably Paleozoic, and the gneiss has a probable protolith of Precambrian and Paleozoic sedimentary and igneous rocks (Weber and others, 1978). The intrusive bodies in the area range in composition from rhyolite to andesite. Fine-grained rhyolite containing quartz and feldspar phenocrysts is common throughout the area (Olson and others, 1985). Structurally, the Richardson region is cut by a northwest-trending fracture system termed the Richardson Lineament. Bundtzen and Reger (1977) interpreted the lineament to extend from Shamrock Creek to Tenderfoot Creek (BD039). The lineament appears to correspond to the distribution of the rhyolite and other intrusive bodies and placer gold deposits (Bundtzen and Reger, 1977, p. 29). Also, the lineament tends to separate gneissic rocks to the northeast from schistose rocks to the southwest (Swainbank and others, 1984). There are several granitic intrusions and associated hornfels on the southwest side of VABM Buck . Numerous northwest-trending shear zones in contact with the intrusions, contain gold-bearing quartz veins (D. Bohme, written communications, 1998). In 1992, trenching and sampling operations defined a 3/4 square mile area with several mineralized intervals. The best trench sample results were 10 meters of 1,750 ppb Au, and 6 meters of 2,354 ppb Au. However, a 1997 exploration program sampled the same trench intervals and failed to reproduce the 1992 gold values. In the hornfels, mineralization is associated with Fe-carbonate alteration, quartz, tourmaline, and pyrite. The system has been interpreted to be shear-hosted and comparable to an intrusive-distal 'True North' style of mineralization (D. Bohme, written communications, 1998). In 1992, approximately 7,750 feet of trenching was completed, and 106 composite rock chip samples were collected. Resampling and exploration activities were conducted in 1997 (D. Bohme, written communications, 1998). Continued exploration in the Shamrock Creek area is expected in 1999. There has been no gold production from the Shamrock Creek prospect.
Workings: Placer gold was first discovered in the Richardson area in 1905. Mining initially occurred on nearby Tenderfoot Creek and extended to other nearby creeks. After peak gold production in 1908, mining in the area declined (Olson and others, 1985). Metz (1991) described early drift mine and surface trench tailings in the Shamrock Creek drainage. In 1992, approximately 7,750 feet of trenching was completed, and 106 composite rock chip samples were collected. Resampling and exploration activities were conducted in 1997 (D. Bohme, written communications, 1998).
Alteration: Fe-carbonate, quartz, and tourmaline alteration is associated with shear hosted gold mineralization (D. Bohme, written communications, 1998).
Production: From 1905 through 1921, production for the Richardson area was approximately 95,000 ounces of gold and 24,000 ounces of silver (Bundtzen and Reger, 1977). Since 1980, mining from the district has produced an additional 10,000 ounces of gold (Olson and others, 1985). Gold production for Shamrock Creek has not been reported separately.

Commodities (Major) - Au
Development Status: None
Deposit Model: Plutonic-related mesothermal, shear-hosted deposit, distal to intrusive?

Other Databases

Link to USGS - Alaska:	BD038

Other Regions, Features and Areas containing this locality

References