Weathering Crust of Kimberlite Rocks: Petrological Types, Zoning, and Formation Processes

Abstract The first comprehensive study of a kimberlite weathering crust was carried out, and the vertical and lateral zonation of the crust was determined. Two types of weathering crusts on kimberlites were identified, with a complete change in the mineral and chemical composition of the original rock: (1) crusts with the preservation of the original volume, structures, and textures of the rock and (2) those with a sharp decrease in the original volume of the rock and its newly formed textures of crushing and foliation. The composition of the weathering crust is controlled by the petrographic composition of the original rocks and the intensity of the effects of magmatic, metasomatic, metamorphic, and sedimentary processes.