Welcome to AlkCarb
Welcome! This website provides an interactive, digitised version of the Alkaline Rocks and Carbonatites of the World volumes, by Dr. Alan R. Woolley. Information can be accessed by using the map feature, search or occurence information.
The definition of alkaline rocks adopted is generally that of Sørensen (1974, p. 7): that they "are characterized by the presence of feldspathoids and/or alkali pyroxenes and amphiboles". The rocks included are, therefore, the nepheline syenites (phonolites) and ijolites (nephelinites), basanites and feldspathoid-bearing gabbroic rocks; peralkaline (i.e. containing alkali pyroxene and/or amphibole) syenite, quartz syenite and granite, together with peralkaline trachyte, comendite and pantellerite. Fenites are also included because of their intimate association with alkaline rocks and carbonatites, as are certain ultramafic and melilite-bearing rocks, including the alnoites and melilitolites. Analcime is treated as a feldspathoid for purposes of the above definition. In the case of alkaline rocks volcanic rocks, when plotted on the TAS diagram, rocks are included as alkaline if they plot in the alkaline fields.