Thunder Creek

Mine, Undetermined

Commodities and mineralogy

Main commodities Au; Cu; Sn; W
Ore minerals arsenopyrite; cassiterite; copper; gold; ilmenite; magnetite; pyrite; scheelite
Gangue minerals garnet; quartz; zircon

Geographic location

Quadrangle map, 1:250,000-scale TL
Quadrangle map, 1:63,360-scale B-3
Latitude 62.497
Longitude -151.003
Nearby scientific data Find additional scientific data near this location
Location and accuracy U. S. Bureau of Mines (1998) locates this mine in the southwest quarter of Section 19, R. 9 W., T. 28 N., of the Seward Meridian. C.C. Hawley and Associates, Inc. (1978, Fig. 4.2-B(3)) show an outline of a claim block on Thunder Creek, a tributary to Cache Creek. This locality is upstream about 0.6 miles from TL032. These two occurrences are two separate areas of placer workings, and appropriately assigned their own ARDF numbers, despite the confusing use of the same name twice.

Geologic setting

Geologic description

Clark and Hawley (1968) describe placer gold associated with an auriferous white quartz conglomerate and breccia deposits at Thunder Creek. The conglomerate is composed of angular quartz fragments mixed with a few rounded quartz and lithic pebbles in fine siliceous clay matrix. Thin layers of lignite are present within the conglomerate which indicates a Tertiary age (Clark and Hawley, 1968).
Capps (1931) reports grades of $2 to $2.50 per cubic yard when gold was at $20.67. The gold fineness ranges from 850.5 to 876.5, averaging 865 (Clark and Hawley, 1968). Concentrates contain gold, ilmenite, magnetite, garnet, zircon, pyrite, arsenopyrite, cassiterite, scheelite and native copper (Cobb and Reed, 1980).
The white quartz conglomerate placers, e.g. Willow Creek (TL042), Thunder Creek (TL032), and Dollar Creek (TL031), represent the oldest placers in the Cache Creek area (Clark and Hawley, 1968). Capps (1925) describes the white quartz conglomerate as the basal unit of the Tertiary Kenai Formation. However Clark and Hawley (1968) suggest that the white quartz conglomerate is older and that the Kenai Group was deposited on it. They believe the auriferous conglomerate is near its original source in part because the characteristics of the gold show a common source that has not moved far or has not been reworked. Further, they indicate that the conglomerate is a product of shearing and weathering in situ of argillic altered, auriferous Tertiary quartz porphyry intrusive rocks and associated quartz veins that were emplaced along northeast, high angle normal faults. The lineaments in Dutch and Cache Creeks represent two of these faults. From these paleo-channels gold was reconcentrated into Cache Creek in more recent time (Mertie, 1919; Clark and Hawley, 1968; C.C.Hawley and Associates, Inc., 1978).
Reed and others (1978) indicate that hydrothermally altered zones similar to those in Thunder Creek are observed along Dollar (TL031) and Thunder Creek (TL032), at the headwaters of Treasure (TL030), Dutch (TL033) and Bear Creeks (TL017) and at an unnamed locality east of McDoel Peak (TL053).
Geologic map unit (-151.005284781139, 62.4964767328769)
Mineral deposit model Placer Au-PGE (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Tertiary and Pleistocene (Clark and Hawley, 1968).
Alteration of deposit Argillic alteration is associated with fault zones (Clark and Hawley, 1968).

Production and reserves

Workings or exploration Placer operations are mapped in Thunder Creek from its confluence with Cache Creek to about a mile and a half upstream (C.C.Hawley and Associates, Inc., 1978). Surface placer operations were probably open-cut, sluice and (or) hydraulic operations.
Indication of production Yes; small
Production notes Capps (1931) reports grades of $2 to $2.50 per cubic yard when gold was at $20.67. The gold fineness ranges from 850.5 to 876.5, averaging 865 (Clark and Hawley, 1968).

Additional comments

Reed and others (1978) indicate that hydrothermally altered zones similar to those in Dollar Creek are observed along Dollar (TL031) and Thunder Creeks (TL032, TL058), at the headwaters of Treasure (TL030), Dutch (TL033) and Bear Creeks (TL017) and at an unnamed locality east of McDoel Peak (TL053).

References

MRDS Number A011581

References

U.S. Bureau of Mines, 1998, Minerals Availability System/Minerals Industry Location System (MAS/MILS), Talkeetna quadrangle: Worldwide Web URL http://imcg.wr.usgs.gov/data.html.
Reporters Madelyn A. Millholland (Millholland & Associates)
Last report date 8/10/1998