Melilitites in the alkaline volcanic succession of the Gorringe bank, Southwestern Portugal

Abstract

Melilitites were found for the first time in the alkaline volcanics of the Gorringe bank. With allowance for previous studies, this indicates the existence of a common melilitite-nephelinite-phonolite alkaline series, which is widely spread as lava fields, dikes, and diatremes in the continental magmatic provinces of Europe, Africa, Asia, and America, often accompanying the formation of carbonatite complexes. This is considered as one of the evidence in support of the continental nature of the alkaline volcanism of the bank. The fact that the volcanics contain fragments of plutonic rocks, which are usually observed in the carbonatitebearing alkaline complexes (melteigites, ijolites, nepheline syenites), makes it possible to suggest the presence of alkaline intrusions of such type at a shallow depth.