Authigenic euhedral kaolins of nano-to-millimetre size were found in d
olomite cavities in the Cambrian basement of the Lodeve Basin, France.
X-ray diffraction, DTA and infrared-spectroscopy data demonstrate tha
t nacrite is the only kaolin phase present in the cavities. Nacrite is
associated with authigenic quartz, barite, dolomite and calcite. Petr
ographic data indicate a contemporaneous growth of nacrite and quartz
after dolomite. In some cavities, barite and nacrite crystallized toge
ther. The crystallization of quartz, nacrite and barite could be the r
esult of fluid influx and trapping in a karstified basement during the
Late Permian extensional tectonic regime that affected the Lodeve Bas
in.