Typomorphic features of various rocks’ products of weathering in connection with diamondprospecting works

Abstract

Results of complex research of different in age ancient crusts of weathering
on various rocks (terrigenous-carbonate rocks of Lower Paleozoic, dolerites, tuffs
and tufogene formations, kimberlites) of the main diamondiferous regions of the
Siberian platform indicated that the most important typomorphic indications of
clay formations in the studied crusts of weathering are as follows: a) omnipresent
dioctahedral hydromica (2М1) in the crust of weathering of terrigenous-carbonate
rocks and its association in the most mature profiles with kaolinite of relatively
ordered structure, than of kaolinite, having been formed at the expense of other rocks;
b) constant availability of trappean formation (tuffs, tufogene rocks, dolerites) in
sections of crusts of weathering together with di- and trioctahedral montmorillonite,
as well as disordered vermiculite-montmorillonite mixed-layered formation, to this
or that degree disordered kaolinite, associated in the crust of weathering of tufogene
rocks with halloysite (at complete absence of micaceous minerals in the products
of weathering); c) the content in the crust of weathering of kimberlites together
with polycationic montmorillonite of a significant quantity of trioctahedral chlorite
(packets δ and δ’), serpentine (structural types A and B) and altered to various degree
phlogopite, including related with it hydromica 1M.