VALDEZ CREEK DISTRICT
The Valdez Creek district is on the southern flank of the Alaska Range at approximately lat 63° 12' N. and long 147°20/ W. The drainage area of Clearwater Creek in addition to that of Valdez Creek is usually included in the district.
Gold was first discovered in this district in 1903, in the gravels of Valdez Creek, but no production was recorded until 1908. The "Tammany Channel," a buried channel representing the course of an ancestral Valdez Creek, yielded most of the placer gold from the district. This channel, discovered in 1904, has been worked by hydraulic and underground methods (Tuck, 1938, p. 113). The chief production has been from placers. Several gold lodes were located, but none were productive to 1936 (Tuck, 1938, p. 121), and no record of any later lode production was found in 1959.
Total estimated gold production through 1936 was about 34,900 ounces, worth about $720,000 (Tuck, 1938, p. 113). The district was virtually dormant during 1937-59.
The geology of the district was described in detail by Ross (1933b, p. 428-444). Triassic(?) meta-sedimentary rocks—argillite, slate, and sericite and chlorite schist with limestone lenses—were intruded by a small batholith of quartz diorite in the northern part of the district and by small stocks and plugs of diorite elsewhere in the district. Structurally, the district is on the northwest flank of a large northeast-trending anticlinal fold; large normal faults trending N. 65° E. cut the metasedimentary rocks.
There are several types of veins in the district, and those showing the most promise, according to Ross (1933b, p. 456), are quartz veins associated with sheared and metamorphosed wallrocks. In their unoxidized state these veins contain pyrite, arsenopyrite, pyrrhotite, and a little chalcopyrite. Native gold occurs in the quartz. Some quartz veins contain abundant calcite (Ross, 1933b, p. 457). Ross (1933b, p. 458) believed the veins were related to hydrothermal activity that followed the intrusion of the dioritic bodies.
The placers are buried channels in which gold was concentrated next to the bedrock floor. The old gorges, eroded into bedrock, are V-shaped and probably were cut into a mature erosion surface (Ross, 1933b, p. 444-445).
WILLOW CREEK DISTRICT
The Willow Creek district, an area of about 50 square miles, is 23 miles by road northeast of Wasilla and 21 miles northwest of Palmer.
Gold-bearing veins were discovered in this district in 1906, but lack of transportation facilities hindered their development and no production was recorded until 1909 (Ray, 1954, p. 35-36). After 1909 the district developed steadily and maintained substantial annual production until 1951, after which there was only sporadic small-scale activity. Total gold production through 1959 was 652,080 ounces; nearly all production was from lode mines.
The geology and ore deposits of this district were described by Ray (1954, p. 10-54). The oldest rock is muscovite-quartz-plagioclase schist. Intruded into this is a mass of quartz diorite, the Talkeetna batholith, which underlies the major part of the district. Dikes of lamprophyre, diabase, aplite, and pegmatite cut the intrusive. The batholith is believed to be of late Mesozoic age. Sedimentary rocks, including conglomerate, arkose, shale, and sandstone of Tertiary (?) age, dip to the south, away from the quartz diorite body. Numerous faults cut the quartz diorite. Those with the larger displacements are postore in age, trend northwest, and dip northeast.
Two types of veins are in the quartz diorite: (1) an older nonproductive group, containing assemblages of chalcopyrite-molybdenite, pyrite-stibnite, or low-grade gold-quartz, and (2) minable gold-bearing quartz bodies in shear zones that occur along the southern margin of the quartz diorite. Vein minerals, in addition to quartz and gold, are pyrite, arsenopyrite, sphalerite, chalcopyrite, tetrahedrite, nagyagite, altaite, coloradoite (?), galena, stibnite(?), and sparse scheelite. Gold commonly occurs as irregular grains in and around nagyagite and as fracture fillings in pyrite, and locally occurs as blebs and stringers in quartz.
