Geological Features of Kvanefield REE Deposit in Southwestern Greenland

Abstract

Kvanefield REE deposit is a world-class REE deposit, which is located at the northern margin of the Ilímaussaq complex in the central part of Gardar igneous province, southwestern Greenland. The intrusion controlling ore is the mesoproterozoic Ilimaussaq complex, where two main varieties of metallogenic parent rocks are distinguished, green aegirine lujavrite and black arfvedsonite lujavrite，which all are agpaitic alkaline rocks, defined as a peralkaline nepheline syenit. The ore bodies are controlled by fractures or interlayer-gliding surfaces, which consist of sodalite lujavrite pegmatite veins and layered arfvedsonite lujavrite. According to mineral assemblage and occurrence form, the ores are divided into arfvedsonite-albite- steenstrupine type and sodalite-aegirine-eudialite type. Specifically, steenstrupine and eudialite are the main bearing rare earth element minerals in the two ores. The steenstrupine have varying ω(REO) contents ranging from 31.5% to 44.9%, with an average of 35.9%, and stone LREE, U and Th enrichment, moreover, which are easily replaced by monazite and uranothorite. In addition, eudialyte have stable ω(REO) contents ranging 1.41% to 1.90%, riching HREE, Nb, and Ta. Two mode of rare earth element occurrence are distinguished in eudialyte, isomorphism and other finely mineral inclusions such as monazite and steenstrupine. With alkaline complex multi-stage diagenesis process of rock mass and alkaline magma in aegirine lujavrite stage of magmatic hydrothermal mineralization and arfvedsonite lujavrite stage magma and mineralization, and form tratiform-lenticular structure on the whole, diagenetic-mineralization model has a different source, multi-stage, with an invasion characteristics.

Keywords

• ilimaussaq
• agpaitic alkaline rocks
• rare earth element
• greenland