Geologic description
The lower one-quarter to one-half mile of Davis Creek has been extensively placer mined by hand and mechanized methods (Kurtak and others, 2002). Gold was discovered on Davis Creek prior to 1908 but there apparently was little mining between World War I and World War II (Maddren, 1913; Reed, 1938). Kurtak and others (2002) report small-scale mining from 1995 to 2001.
Placer gold was recovered on bedrock along the modern channel of Davis Creek and on benches on the north side of the creek. For about a quarter mile above its mouth, Davis Creek cuts through gravel up to 50 feet thick that was probably deposited by the ancestral South Fork of the Koyukuk River. The modern stream and bench placers may be the result of reworking this ancestral gravel. Samples of the placer concentrates are anomalous in bismuth, tungsten, zinc, and copper. One placer concentrate assayed 1,591 part per million (ppm) bismuth and a soft metallic grain in the concentrates may have been native bismuth.
The total production is unknown but 242 ounces of gold were produced from 1900 to 1909 (Maddren, 1913). Kurtak and others (2002) estimate a resource of 23,000 cubic yards of gravel with an average grade of 0.016 ounce of gold per cubic yard. Bedrock near the mouth of the creek is Paleozoic chlorite schist with lenses of metamorphic quartz up to 1.0 foot thick (Kurtak and other, 2002). Select samples of quartz with pyrrhotite contained up to 150 parts per billion gold and 444 ppm copper. The schist is overlain by Jurassic, mafic volcanic and intrusive rocks, Jurassic ultramafic rocks, and Cretaceous quartz-pebble conglomerate. |
