Abstract Alkaline igneous rocks and carbonatites are compositionally and mineralogically the most diverse of all igneous rocks and, apart from their scientific interest, are of major, and growing, economic importance. They are valuable repositories of certain metals and commodities – the only significant sources of some of them – and include Nb, the rare earths, Cu, V, diamond, phosphate, vermiculite, bauxite, raw materials for the manufacture of ceramics, and potentially Th and U. The economic potential of these rocks is now widely appreciated, particularly since the commencement of the mining of the Palabora carbonatite for copper and a host of valuable by-products. Similarly, the crucial economic dominance of rare earth production from carbonatite-related occurrences in China has stimulated the world-wide hunt for related deposits. This volume describes and provides ready access to the literature for all known occurrences of alkaline igneous rocks and carbonatites of Antarctica, Asia and Europe (excluding the former USSR), Australasia and the oceanic islands. More than 1200 occurrences from 59 countries are outlined, together with those of 57 oceanic islands and island groups. The descriptions include geographical coordinates and information on general geology, rock types, petrography, mineralogy, age and economic aspects, with the principal references cited. A brief description is also given of alkaline minerals in meteorites and of alkaline rocks on Mars and Venus. There are 429 geological and distribution maps and a locality index. As has been demonstrated by the three earlier volumes, Alkaline Rocks Part 4 is likely to be of considerable interest to mineral exploration companies, as there are no comprehensive published reviews of the economic aspects of the alkaline rocks. It will also interest research scientists in the fields of igneous petrology and volcanology, and geologists concerned with the regional distribution of igneous rocks and their geodynamic relationships.

A general feature of alkaline and related magmatism is repetition of eruption at the same site over long time intervals. Alkaline activity is widespread across Africa, where there are more than one thousand complexes. Eruption is typically localized by older lithosphere structures. As more igneous age dates have become available, examples of repetition have been found for all areas. Histograms showing numbers of dates against age show distinct spikes highlighting a pattern of episodic, synchronous repetition at many different sites across the continent. Most of the spikes match the times of major global events, such as orogenic periods, while the most exceptional igneous age peaks (in the Cretaceous and Tertiary) correlate with the main collision episodes between Africa and Europe. Cretaceous activity spans the period of the Cretaceous normal (CN) superchron, starting shortly after completion of the breakup of Gondwanaland. Major peaks of kimberlite activity also mark the start and end of the CN superchron, emphasizing the singular conditions that prevailed during this period. The igneous age spikes reveal that the Africa plate contains a sensitive record of global events from the period between 180 and 0 Ma, such as major changes in oceanic magmatism and tectonics. All these global episodes are also registered in the geomagnetic record. These correlations indicate coupling between plate tectonics and the core, raising questions that need to be addressed by models of whole-Earth dynamics. The current information on Africa is given in a synoptic review, with new maps and diagrams showing all presently available data, with unpublished material to be made available on the Web. More data from all the continents should help sharpen the details of global dynamics and extend the picture into the pre-Mesozoic.