Alaska Gold Rush History and Genealogy

 
   

Kenai Peninsula Region

 

   

Placer Deposit of Alaska GEOLOGICAL SURVEY BULLETIN 1374

The Kenai Peninsula region is the Kenai Peninsula south of Turnagain Arm and west of the divide between Cook Inlet and Prince William Sound.

West of a line extending from the head of Kachemak Bay to Turnagain Arm near the mouth of the Chickaloon River, most of this region is considerably less than 1,000 feet above sea level, though rolling hills and a few steep—sided ridges rise to elevations of nearly 3,000 feet. The Kenai Mountains to the east are chaacterized by high relief, and many of the summits are between 4,000 and 6,000 feet in altitude. Deep fords, many with glaciers at their heads, embay the coastline. Remnants of Pleistocene ice that covered the entire peninsula and extended far into the sea are preserved as alpine glaciers and as the Harding and Sargent Icefields. Proglacial lakes occupied much of the lowland during parts of Pleistocene time. Two large lakes in the lowlands, Skilak and Tustuména, lie behind recessional moraines, although the Kasilof River, which drains Tustumena Lake, has cut down to bedrock. The drainage of the northern part of the lowland is still not fully integrated. The entire region is free of permafrost. The Kenai Mountains, the highest parts of which are virtually unexplored, are made up of limestone, chert, and tuff of Triassic age that rest on metamorphosed older volcanic and clastic rock~ and are overlain by Jurassic volcanics and a thick sequence ol intensely deformed, but only slightly metamorphosed, slate and graywacke, mainly of Late Cretaceous age (Kelly, 1963, p. 280-284; Berg and Cobb, 1967, p. 76). These rocks were intruded by Tertiary (?) dikes, sills, and stocks that range in composition from granite to peridotite (Berg and Cobb, 1967, p. 76; Richter, 1970 p. B4—B5). The lowland and adjacent parts of Cook Inlet are underlain by many thousands of feet of poorly consolidated mainly continental, rocks of Tertiary age that rest on a basement of rocks similar to those exposed in the Kenai Mountains (Mac. Neil and others, 1961; Kelly, 1963). The Tertiary rocks are buried by Quaternary deposits except along sea cliffs around the southern part of the Kenai Lowland, in isolated inland exposures, anc in a few small remnants resting on older rocks on the southeast shore of Kachemak Bay and at Port Graham.

Only gold, alloyed with silver, and chromite have been mined from lodes in the Kenai Peninsula region, although copper, lead zinc, molybdenum, antimony, and nickel minerals have been found (Berg and Cobb, 1967, p. 73—82, fig. 14; Richter, 1970). The chromite is in two dunite and pyroxenite stocks in the southern part of the Homer district. Quartz veins, in graywacke and slat and in small quartz diorite stocks and granite dikes carry gold and various sulfide minerals. The lode gold production of the region probably was about 19,000 ounces. Placer gold was first discovered in Alaska on the Kenai Rivet in 1848 (between loc 5 and 7) by P. P. Doroshin, a mining engineer employeed by the Russian-American Co. In 1850—51 he attempted to mine gold on a stream that flows into Skilak Lake and on two small tributaries of the Kenai River between Skilak and Kenai Lakes but failed to find enough to repay his effort (Moffit, 1906a, p. 8). Later placer mining was concentrated the parts of the Hope district where lode deposits were extensively explored and mined. A few streams and beaches in other parts of the Kenai Peninsula region were worked on a small sea. In the area around Nuka Bay, however, where there are many gold-bearing lodes, placer gold has not been found. As production statistics have generally included the output of Crow Creek at neighboring streams in the Anchorage district in that credited to the Kenai Peninsula region, accurate figures are not available The total for the Kenai Peninsula from about 1895, the first yet production was officially reported, through 1960 was probably between 100 and 105 thousand fine ounces of gold and an unknown amount of alloyed silver. Small-scale placer operations were reported in 1961 and 1962.

US Gelogical Paper 610

KENAI PENINSUI,A DISTRICT The Kenai Peninsula is near the center of the southern coastline of Alaska, immediately northeast of the Alaska Peninsula. The districts of Moose Pass-Hope, Girdwood, and Turnagain Arm-all in the central and northern part of the peninsula-have been combined in this discussion because most of their production data have been combined under "Kenai Peninsula." Numerous small placers were discovered in the Turnagain Arm area in the early 1890's, but no significant production occurred until news of the auriferous gravels on Mills and Canyon Creeks brought several thousand prospectors to the area in 1896 (Martin and others, 1915, p. 182-183). Two years later another influx occurred. In a short time the small richer deposits were exhausted and the hand-operated rockers· and sluices were supplanted by hydraulic plants that successfully mined the large reserves of low-grade gravels. Lode mining, overshadowed by the placer operations, has been conducted chiefly in the Moose PassHope camp and to a lesser degree in the Girdwood camp. The first indications of economic lode deposits were noted in 1896, but interest was diverted for a number of years to the more accessible placers. The lode deposit at the Hirshey mine, discovered in 1911, became the most consistently productive in the district (Tuck, 1933, p. 489-494). Lode mining continued sporadically until the end of World War II, when it dwindled to almost nothing. Total recorded gold production from the Kenai Peninsula from 1895 through 1959 was 23,700 ounces from lodes, 96,500 ounces from placers, and 175 ounces from undifferentiated sources. Data from 1931 through 1945 are incomplete, so that the figures given here are minima. The geology of the Kenai Peninsula was described by Martin and others (1915), Tuck (1933), and Park (1933). The oldest rocks on the peninsula are schists and crystalline limestones of uncertain age; however, the most widely distributed rocks are slates and graywackes that range in age from Paleozoic or Early Triassic to possible Late Cretaceous (Martin and others, 1915, p. 33-35). Granitic intrusive masses are abundant in the slaty rocks along the southern and eastern coasts. The Kenai Formation, of Eocene or younger Tertiary age, is exposed in the low country in the southwest part of the peninsula, north of Kachemak Bay, and consists of coal-bearing sand and clay. This formation is 15,000-20,000 feet thick and contains economically important oil and gas accumulations (Lian and Simonson, 1962, p. 271). Quaternary gravelsmostly till, outwash, and terrace sands and gravels -cover vast areas of lowlands in the west and northwest parts of the peninsula. The pre-Tertiary rocks that comprise most of the mountainous part of the peninsula are intricately folded whereas the Tertiary rocks, which occupy the low areas of the peninsula, are either horizontal or only gently warped into folds in which dips are generally less than 10° (Barnes and Cobb, 1959, p. 227). The lode deposits of the Moose Pass-Hope camp consist of fissure veins. Mineralized acidic dikes are 12 PRINCIPAL GOLD-PRODUCING DISTRICTS OF THE UNITED STATES also in the district, but the gold production has been by a small batholith of quartz diorite in the nortfrom the fissure veins that cut across the slaty ern part of the district and by small stocks and cleavage of the slate and graywacke country rocks. plugs of diorite elsewhere in the district. StrucThe veins strike in all directions and have an aver- turally, the district is on the northwest flank of a age dip of 45° north or west (Tuck, 1933, p. 490). large northeast-trending anticlinal fold; large norThe ore minerals are arsenopyrite and small mal faults tre~ding N. 65° E. cut the metasedimenamounts of galena, sphalerite, pyrite, and chalco- tary rocks. pyrite in a gangue of quartz, calcite, and ankerite There are several types of veins in the district, (Tuck, 1933, p. 491). Free gold occurs in the quartz, and those showing the most promise, according to commonly near accumulations of galena and sphal- Ross (1933b, p. 456), are quartz veins associated - erite. with sheared and metamorphosed wallrocks. In The placer deposits of the Kenai Peninsula, de- their unoxidized state these veins contain pyrite, scribed by Martin, Johnson, and Grant (1915, arsenopyrite, pyrrhotite, and a little chalcopyrite. p. 181-208), are most productive in the northern Native gold occurs in the quartz. Some quartz veins part of the peninsula along the various streams- contain abundant calcite (Ross, 1933b, p. 457). Crow, Resurrection, Palmer, Bear, and Sixmile Ross (1933b, p. 458) believed the veins were reCreeks-that debouch into Turnagain Arm. Farther lated to hydrothermal activity that followed the south, the gravels of Canyon, Mills, Falls, and intrusion of the dioritic bodies. Cooper Creeks, and of the Kenai River have yielded The placers are buried channels in which gold some placer gold. The deposits were formed in Qua- was concentrated next to the bedrock floor. The old ternary time by postglacial streams reworking and gorges, eroded into bedrock, are V-shaped and probresorting the debris that choked the valleys after ably were cut into a mature erosion surface (Ross, the retreat of the glaciers. Present streams that 1933b, p. 444-445). have incised their courses in the unconsolidated material have left terraces and have further reworked the gravels. The productive glaciers are along these streams and in channel deposits in the terraces.

  Districts: Hope, Homer, Seward. Moose Pass, Girdwood, Turnagain Arm
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