An investigation of rare-earth mobility: Fenitized quartzites,Borralan complex,N.W. Scotland

Examples of fenitization of pure quartzites provide valuable insight into the relative mobility of elements. This investigation of fenites from the Borralan complex shows that rare-earth elements are mobile and added during fenitization of quartzite. The resulting normalized patterns are distinctive in their enrichment of the light rare earths and steep drops in the interval Nd-Eu. In terms of rare-earth geochemistry, no difference can be found between the sodic and the potassic trends of fenitization at Borralan. Concentrations of mobile elements define straight-line plots through the origin, heretofore considered a criterion indicative of a fractional crystallization process.Present address: Department of Geological Sciences, McGill University, 3450 University Street, Montreal, Que. H3A 2A7, Canada