Madagascar

There is no complete account of the alkaline igneous rocks of Madagascar but the general review of the volcanic rocks by Brenon and Bussiere (1959) describes briefly the main extrusive fields and their general chemical characteristics. The fullest, and still the most detailed, descriptions of the alkaline rocks, particularly of the more unusual rock types, will be found in the three volume Mineralogie de Madagascar of Lacroix (1922a and b, 1923), but at the time of his work the distribution and field relationships of the rocks were not well known. The three sheets of the 1:1,00,000 geological map of Madagascar (Besairie, 1964) and eight sheets of the 1:500,000 series (Besairie, 1969a and b; 1970a and b; 1971a and b) show clearly the distribution of all the principal alkaline rock occurrences.