The Neoproterozoic, post-collisional, Graciosa Province (southern Brazil) comprises several A-type intrusions and related volcanics of alkaline and subalkaline (or aluminous) petrographic associations. U-Pb age determinations, trace element, and Hf and O isotopic compositions were obtained for zirco...

Occurrences of alkaline and carbonatite rocks with high concentrations of rare earth elements (REE) are a defining feature of Precambrian geology in the Mojave Desert of southeastern California. The most economically important occurrence is the carbonatite stock at Mountain Pass, which constitutes t...

The Shuiquangou syenitic complex consists of melasyenite and leucosyenite. In the northeastern part, there is a small area where the leucosyenite was affected by alteration. The altered leucosyenite contains much higher concentrations of high-field strength elements (HFSE), especially Nb, Zr, REE an...

This paper presents elemental evidence that the mafic unit of the Caledonian Glen Dessarry syenite (northern Scotland, U.K.) has been variably contaminated with material derived from the surrounding Moine metasediments. Uncontaminated portions are shown to have trace-element abundances and ratios si...

Concern about security of supply of critical elements used in new technologies, such as the Rare Earth Elements (REE), means that it is increasingly important to understand the processes by which they are enriched in crustal settings. High REE contents are found in syenite-dominated alkaline complex...