INTRODUCTION
The Carr Fork property is situated in the Bingham Mining District located on the east slope of the Oquirrh Mountain range in Utah. The mine is adjacent to and lies west of Kennecott's Bingham Pit some 25 miles southwest of Salt Lake City. The Bingham Mining District contains one of the largest copper reserves on North America. Mineralization is associated with the Bingham stock which intruded through some 16,000 feet of sedimentary formations. Mineralization and alteration zoning was developed radially from the Bingham stock with lower grade disseminated copper mineralization centrally located in the stock and adjoining quartzites. In addition, several garnetized limestone beds abutting the stock were also well mineralized. These skarns will be Carr Fork's initial mining target. Of the several limestone beds, only two, the Yampa and the Highland Boy have significant commercial interest at present. These beds which are 50 feet to 150 feet thick and are separated by 200 to 400 feet of quartzite were highly folded, thrusted and faulted, resulting in a dip variance from 20 ° to vertical. The predominant dip, however, is between 20 ° and 45 ° from horizontal. Quartzites surrounding the limestone beds were subjected to the same degree of tectonic activity with resultant intense fracturing and stress relief. The limestone beds which have a higher elastic modulus and which also experienced fracture healing during mineralization appear to have greater competency and strength than the quartzites. Four shafts nominally 3500 feet deep will provide access to the mine which will be a highly mechanized trackless operation, designed to produce 14,000 tons per hoisting day. First production is scheduled for the last quarter of 1979.
HISTORY
Bingham Canyon's first mining claim was staked on September 17, 1863. The railroad arrived at Bingham in 1873 and active exploitation of the known silver-lead deposits followed. The first shipment of copper was made in 1896 when 5000 tons of highgrade copper ore from limestone replacement deposits were shipped from the Highland Boy mine. Active mining continued on the claims, currently owned by Anaconda, until 1947. The National Tunnel and Mines Company, the last company operating in the area, mined predominantly in the steeply dipping copper bearing Yampa limestone to a depth of 3,300 feet below surface. After acquiring the Carr Fork ground in 1948, Anaconda maintained an active exploration program which on September 6, 1974, resulted in a production decision. Since release of the project, we have installed a permanent hoisting plant and sunk the service shaft 2500 feet; erected a permanent hoisting tower on the production shaft; sunk the exhaust shaft 1600 feet; and completed underground sinking preparations and sunk the fresh air shaft 300 feet. In addition, old workings are being dewatered.
CURRENT ROCK MECHANICS ACTIVITY
Mining plans for Carr Fork are not in final form. Before they are, additional "definition" drilling, plus a substantial rock mechanics data input and analysis will be utilized. Some rock mechanics data has been collected to date, and this information was analyzed with respect to rock excavation and support in progress.