Abstract

The Wyoming craton in the western United States, is considered to be a favorable terrane for the discovery of diamond deposits. The craton hosts a variety of ultramafic, ultrabasic, and ultrapotassic rocks, many of which have potential to host diamonds, and several of which are known to be diamondiferous.

The Wyoming craton is separated into two provinces known as the Wyoming and Colorado Provinces. The Wyoming Province consists of a relatively stable Archean basement underlying much of Montana and Wyoming and extending into the adjacent states of Colorado, Utah, Idaho, and Nevada, and continues north into southernmost Alberta and Saskatchewan. The Colorado Province is a cratonized Proterozoic basement terrane that underlies much of Colorado and a small portion of southeastern Wyoming. Although most exploration geologists would consider the Wyoming Province the most favorable terrane for commercial diamond deposits based on its age, the Colorado Province has so far been the most productive province in the United States for diamonds.

The presence of numerous kimberlitic indicator mineral anomalies in stream sediments, anthills, and paleoplacers, and the occurrence of some geophysical and remote sensing anomalies within the craton, suggest the possibility of undiscovered, mantle-derived, igneous rocks of kimberlitic affinity. Known kimberlite, lamproite, and diamond fields will probably be extended with continued exploration.