Magmaclasts in kimberlite

This contribution presents an updated descriptive scheme for magmaclasts in kimberlite, resulting from over 40 combined years of mapping, logging, and petrographic studies by the authors of hundreds of kimberlites and related rocks globally. Systematic description of the essential characteristics of magmaclasts enables their identification, classification and interpretation. Magmaclasts are fluidal-shaped bodies of kimberlite magma (now solidified) formed by any process of magma disruption prior to solidification. The key characteristics used to discriminate the two main varieties, melt segregations and melt-bearing pyroclasts, are explained and illustrated, as well as the features of melt-bearing pyroclasts in the two main classes of pyroclastic kimberlite. Accurate classification of magmaclasts in coherent and volcaniclastic kimberlites is fundamental for the development of valid geological models in support of exploration, evaluation and mine planning. Magmaclasts are used to determine parental magma type, the textural-genetic classification of the infills of kimberlite bodies, the presence of different eruptive phases (and mixing between them), and the emplacement history of a kimberlite. They can also provide insight on potential modification of the inherent diamond distribution of a kimberlite. •Magmaclast is a descriptive term for melt segregations and melt-bearing pyroclasts.•Magmaclasts are an important component of many kimberlites.•A standardized approach to magmaclast description is valuable.•Magmaclast studies are used with other data to generate reliable kimberlite models.