Ages of Volcanic and Intrusive Rocks in the Bingham Mining District, Utah

Abstract

Abstract Latitic volcanic rocks about 39 to 38 Ma and 33 to 31 Ma occur along the eastern flank of the Oquirrh Mountains in the vicinity of the Bingham Canyon porphyry Cu-Au-Mo deposit. Extrapolation of the basal contact of the 39 Ma volcanic rocks shows that they likely covered parts of the Bingham intrusions less than 500 m above the pre-mining surface. Some Bingham intrusions may have vented to the surface to help form the volcanic sequence. Minette and shoshonite lavas occur in subordinate amounts within the volcanic sequence. Minette dikes (37.74 ±0.11 Ma) in the Bingham Canyon ore body are the same age as late mineralized porphyry dikes (37.72 ± 0.09 Ma) and unaltered minette flows (37.82 ± 0.14 Ma). These ages confirm that minette magma may have played a role in the petrogenesis of ore-related intrusions in the Bingham mining district.