Carbonatites complexes and associated REE mineral system: Significance in modern technology

Abstract

Carbonatites, comprising both intrusive igneous and hypabyssal rocks, are among the major reserves of rare earth elements (REE) on Earth, and are hence critical for modern technology. Major REE minerals in these rocks include bastnaesite, monazite, xenotime, pyrochlore and apatite. REE important military applications, computer displays, sonar, hybrid vehicles, digital cameras, etc. REE mineralization is usually associated with potassic rocks, carbonatite and nephelinitic rocks. In Western Australia, important carbonatite systems include Copperhead, Mt Weld and the Gifford Creek ferrocarbonatite complex. In terms of whole-rock alteration, fenitisation, which occurs in aureoles of carbonatite and alkaline complexes. Associated mineralisation is usually related to alkali metasomatism in anorogenic ring complexes, in which unusual concentrations, apart from REE, contain F, Zr, Ba, Nb, Th, U, Ta and W. Ring complexes of the ijolite-carbonatite association may contain economic amounts of pyrochlore, columbite, cassiterite, monazite and zircon. Pyrochlore generally occurs in sodic metasomatized peralkaline granites. Good examples of REE mineral systems are the Pilanesberg Complex, the Pienaars River Complex and the Lolekop carbonatite complex.