Assessment of mineral resource tracts in the Chugach National Forest, Alaska

Abstract

Locatable minerals have been produced from the Chugach National Forest (CNF) for nearly 100 years. Past gold production has come from the Kenai Peninsula and the Girdwood, Port Wells, and Valdez areas. Copper and by-product gold and silver have been produced from mines at Ellamar, on Latouche Island, and near Valdez. Many of the past-producing properties were not mined out and contain significant inferred reserves of gold, copper, lead, zinc, and silver. This report outlines mineral resource areas (tracts) that contain both identified and undiscovered mineral resources. These tracts were drawn on the basis of one or more of the following criteria: (1) geochemical anomalies, (2) favorable geologic units, (3) presence of mines, prospects or mineral occurrences, and (4) geophysical anomalies. Bliss (1989) used six mineral deposit models to describe the types of deposits known from the CNF. Of these deposit types, only four are sufficiently known and defined in the CNF to be suitable for consideration in outlining and ranking of mineral resource tracts; these deposit types are: (1) Cyprus-type massive sulfide, (2) Chugach-type low-sulfide goldquartz veins, (3) placer gold, and (4) polymetallic vein. The U.S. Bureau of Mines indicated that most of the inferred mineral reserves in the CNF would not be economic to produce under current prices. Small-scale placer gold operations are a possible exception. Other known resources that have recorded past production (oil, coal, rock, sand, and gravel) are not addressed in this report. The CNF, the second largest national forest in the United States, covers roughly 23,000 km 2 (9,000 mi 2). This area includes Prince William Sound, the largest embayment along the coast of Alaska between Cook Inlet and Cape Spencer (near Glacier Bay). Prince William Sound includes numerous islands, the largest of which are Montague, Hinchinbrook, Knight, and Hawkins Islands (fig. 1). There are numerous non-forest land in holdings within the boundaries of the Chugach National Forest including Native corporation lands, city and state lands, and patented mining claims. Under the provisions of the Alaska Native Claims Settlement Act of 1971, several Native villages/corporations selected about 400,000 acres of forest land for withdrawal as private land, and in 1984 these boundaries were being adjusted (Chugach National Forest Map, 1994). Continued adjustments of land ownership within the forest are the result of settlements following the Exxon Valdez oil spill claims. These settlements have resulted in some lands being returned to the national forest for management.

USGS Mineral Resources Program--Supporting Stewardship of America's Natural Resources

“…When the Forest Plan was revised in the late 1990s, the Forest managers requested that the USGS conduct an additional assessment of mineral resource tracts outlined in the previous study. A report by Nelson and Miller (2000) Project designers wanted to increase understanding of the interrelationships among the ecological, biophysical, social, and economic conditions, trends, risks, and opportunities within the planning area. Creation of the project was driven by a wide range of concerns, including forest and rangeland health, uncharacteristically intense wildfires, endangerment of selected fish and wildlife species, and concerns about social and economic well being of local communities.…”

“…In the 1970s, the western part of the Forest was studied as part of the Alaska Mineral Resource Assessment Program (AMRAP). In the 1980s, a broader regional study of the entire Forest was conducted under provisions for mineral resource surveys as outlined in the 1964 Wilderness Act (Nelson and Miller, 2000).…”