high depth of melting, which yields more mafic magmas.Leaving aside complex petrogenetic arguments, it is fair to say that the essential components in lamprophyre genesis are Either scheme may apply to some, but not all, occurrences and variations of the broader group of rocks known as lamprophyres and melilitic rocks. Mitchell considered the lamprophyres as a " facies" of igneous rocks created by a set of conditions (generally late, highly volatile differentiates of other rock types). While modern concepts see orangeites, lamproites and kimberlites as separate, a vast majority of lamprophyres have similar origins to these other rock types. Lamprophyres are similar to lamproites and kimberlites. Rock considered lamprophyres to be part of a "clan" of rocks, with similar mineralogy, textures and genesis. Mitchell has suggested that rocks belonging to the "lamprophyre facies" are characterized by the presence of phenocrysts of mica and/or amphibole together with lesser clino pyroxene and/or melilite set in a groundmass which may consist (either singly or in various combinations) of plagioclase, alkali feldspar, feldspathoids, carbonate, monticellite, melilite, mica, amphibole, pyroxene, perovskite, Fe-Ti oxides and glass.Ĭlassification schemes which include genetic information, may be required to properly describe lamprophyres. For example, the TAS scheme is inappropriate due to the control of mineralogy by potassium, not by calcium or sodium. They are classified under the IUGS Nomenclature for Igneous Rocks (Le Maitre et al., 1989) separately this is primarily because they are rare, have peculiar mineralogy and do not fit classical classification schemes. Lamprophyres are not amenable to classification according to modal proportions, such as the system QAPF due to peculiar mineralogy, nor compositional discrimination diagrams, such as TAS because of their peculiar geochemistry. Modern science treats lamprophyres as a catch-all term for ultrapotassic mafic igneous rocks which have primary mineralogy consisting of amphibole or biotite, and with feldspar in the groundmass.
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