Distribution of Platinum-group Elements in an Ultramafic Complex Near Rainbow Mountain, East-Central Alaska Range.
Proc Symp on Process Mineral During Metall Soc Ann Mtg Denver Metall Soc 1988 :197-220
According to this U.S. Bureau of Mines study, near Rainbow Mountain in the east-central Alaska range an Ultramafic complex forms a sill- like intrusion composed of dismembered bodies exposed along the south side of the Denali Fault and Broxson Gulch Thrust. The complex comprises dunite and peridotite with lesser gabbro, which together exhibit poorly defined, steeply dipping compositional layering. The complex hosts four types of copper-nickel occurrences which have characteristic platinum-group elements (pge), gold, and cobalt distributions. Three of the occurrence types are considered to have formed as a result of primary mineral segregations that developed during intrusion of the complex. The fourth type of copper-nickel occurrence formed as a result of postmagmatic hydrothermal fluids at intrusive contacts. Scanning electron microscope examination indicates that pge occur as micrometer-size telluride and arsenide minerals.
Proc Symp on Process Mineral. During Metall Soc Ann Mtg, Denver; Metall. Soc., 1988, Pp 197-220