The Geology of Asarco’s Young Mine
The Young Mine is located in Jefferson County, Tennessee, on U.S. Highway 11-E about 15 miles (25 kilometers) northeast ofKnoxville. It is situated near the center of the Mascot - Jefferson City zinc district which lies within the Valley and Ridge Province. Sphalerite deposits occur within the Kingsport and Mascot Formations, located in the upper part of the Lower Ordovician Knox Group.
The mine is located atop a physiographic do mal structure known locally as Hodges dome (Fig. 1 0). Geographically, it lies between two low-angle thrust faults: the Mill Spring. to the north, and the Rocky Valley to the south. This structure is cut by numerous high-angle faults, most of which exhibit minor to moderate vertical and/ or horizontal displacement. One exceptional high-angle reverse fault displaces the north flank of the dome downward approximately 100 feet (30 meters). The dome is considered to be of pre-Cambrian age, while the faulting is post-ore and is thought to have occurred during the Appalachian orogeny (Upper Paleozoic).
The mine was developed from a rectangular 7 -compartment shaft which was sunk on the north flank of the domal structure to a depth of 936.4 feet (285.4 meters). Production was started in 1955. Output has increased, due to increased mechanization and the addition of the Beaver Creek shaft in 1989, to a point where the current production of crude ore is approximately 4787 tons per day, yielding an annual production in excess of 1. 25 million tons. Mining is generally by selective open stoping involving three stages: slabbing, backstoping, and benching.