Features of micaceous formations in kimberlite

Abstract

Eruptive and sedimentary rocks, as well as metamorphic differences of the latter, composing continental blocks of the Earth crust during hypergenesis and lithogenesis of arising in these cases products, suffer natural specific changes (alterations) depending on petrochemical and genetic features of initial rocks. Products of weathering of non-micaceous differences of erupted rocks, as well as sedimentary (both non-micaceous and micaceous) differences, owing to rather fine particle size of primary and secondary minerals should be studied in smaller than 0.001 mm fraction. As opposed to this, objective evidence about hypergene alteration in micaceous differences of erupted rocks, mainly due to larger size of micaceous particles, can be received only during complex research of both smaller than 0.001 mm fraction and of the rock in whole. The presence of micaceous minerals of sericite type (that is disperse muscovite) in metamorphosed rocks at this points to an irreversible alteration process of the coming from dry land detritus even at the latest stages of lithogenesis. Special attention is paid to the study of minerals-neoformations of kimberlite rocks, formed at postmagmatic stage, the specified typomorphic features of some of which can be successfully used during prospecting of diamond deposits. Basing on complex research of accessory and rock-forming minerals of kimberlite rocks the processes of secondary mineral formation have been followed in details. The products of kimberlite rocks alteration have been researched; the scheme of initial minerals transformation has been constructed. Redeposition of products of weathering of various composition rocks near denudation areas and accumulation mainly in freshwater basins, as well as small thickness of the formed sedimentary layers and their insignificant immersion determined weak hydrodynamic impact of environment on allothigenic minerals (argillaceous, first of all), which has not led to sufficient diagenetic alteration. That is why redeposited in ancient sedimentary thick layers products of various types of crusts of weathering preserve structural and chrystallochemical features in relation to the minerals of eluvial thicknesses, which allow tracing the ways of terrigenous material arrival into sedimentation basins (including diamondiferous material).