Kaolin Deposits of Charentes Basin, France
deposits formed sedimentarily
and then confined by other geological structures.
The geological unit called Charentes
basin is composed of Eocene
deposits, laid above karstic limestone
formations of the Campagnien
, in the North of the Aquitaine Basin
. The kaolin
clays of Charentes belong to this mainly continental, tertiary formation often referred as “siderolithic”, of which the principal outcrop is situated in the South of the Charente Maritime
department, 35 miles going North-East from Bordeaux city. The quarries are scattered along a 20 mile long, 7 mile wide, North - South band.
The clay concentrations of economic value are composed of a succession of clays, sands and pebbles. This torrential-stream deposit, close to enlaced rivers, laid to the deposition of sandy-clayey materials, with a variable iron content, coming from a lateritic weathering, of the French “Massif Central” granites. The presence of numerous lignite
rich levels indicates that the deposit was performed in the presence of a lot of organic matter, leading to important pedogenetic and diagenetic possibilities of evolutions. These chemical and mineralogical evolutions (dissolution–crystallization) allow the neo-formation of kaolin and gibbsite
, as well as iron sulphide
.Delineau,... Read More