ABSTRACT
This chapter deals with the characteristics of REE distribution in kimberlites, komatiites, meimechites, picrites, and lamproites. All these rocks are characterized, on the one hand, by relatively increased contents of refractory components including magnesium, and, on the other, by more or less increased contents of incompatible elements including REE, particularly light ones. According to the commonly held view, all these rocks crystallized at relatively moderate depths or under surface conditions (Bogatikov et al., 1981). At the same time, many mineralogical, petrographical, geochemical, metallogenic, and genetic aspects of the rocks in question as well as the mechanisms of their mother melt generation remain the subject of ever more-detailed explorations and discussions. Special attention is paid to kimberlites and lamproites, which are genetically connected to diamondiferous deposits, and to komatiites, which are often associated with different-sized deposits of nickel, copper, and platinum metals. In summarizing the available data on the rare earth composition of the said varieties of small-depth rocks, use was made of the results, both borrowed from the literature and obtained with the author’s participation, of about 300 original analyses of samples from a great number of manifestations.
