Calciocarbonatites appear in the Basal Complex as veins, breccias, and shear bands.

In the northern part of the island of Fuerteventura there is a series of outcrops belonging to the Ultra-alkaline series and are particularly interesting because of the complexity of its lithology and how good their outcrops.

We can distinguish three zones:
— Massif of "Barranco de Agua Salada" located in a small ravine tributary of Esquinzo;
— Massif of "Los Jablitos";
— Massif of "The Montañetas".
The latter two are both situated in the ravine of "Los Encantados", also a tributary of Esquinzo.

In these outcrops a great variety of rocks such as ijolites, syenites, nepheline syenite, nephelinites, carbonatites (sovites-alvikites) are found with pegmatitic zones and zones of brecciation, and complex processes of metasomatism and recrystallization.

A major 100 m-wide anastomosing normal-dextral shear zone divides the Esquinzo ultra-alkaline complex into two blocks showing important different lithological features:

— In the southwestern block, perovskite-bearing pyroxenites and perovskite-bearing melteigite-ijolite rocks cut by late nephelinite and phonolitic nephelinite dykes are predominant, while carbonatites occur in limited amounts.

- In contrast, in the northeastern block, there are no nephelinite or phonolitic nephelinite dykes, but carbonatites, nepheline syenites and pegmatite ijolites are very abundant. Cross-cutting relationships between the different lithologies are shown in an E–W geological cross-section.

Other Regions, Features and Areas containing this locality

References