The geochemistry of the Rössing leucogranites and several associated metasediments, Rössing, Namibia

Abstract

Abstract provided by author:

The Rare-Earth Elements show an enrichment in the light Rare-Earths, this could be due to either fractionation or a redistribution by fluoride rich fluids. The positive Eu anomaly for the most altered samples suggests that REE3+ ions have been removed by fluoride fluids, while Eu2+ has been retained in the feldspar lattice

The leucogranites are highly fractionated and altered S-type granites, emplaced at a relatively high stratigraphic level in the late stages of orogeny

Both the leucogranite and the country rock have been extensively altered close to their contact, so the leucogranites acted as pathways for later, low temperature (200 *C) fluids, nevertheless, fresh closed system (magmatic) leucogranites can still be found. Both mineralogical and chemical evidence suggest that dominant potassic fluids with a significant CO2 content have served to flush synmagmatic uranium out of the altered system