Humid tropical weathering of quartzite in southeastern Venezuela

Auteurs :
CHALCRAFT, D.
PYE, K.

Description :
Optical microscope, SEM and X-ray diffraction analyses of fresh and weathered rock specimens from Mount Roraima suggest that weathering of the quartzite takes place primarily by direct solution of quartz grains and silica cement, and does not involve an intermediate stage of hydration of quartz to opal as suggested by previous authors. During the weathering process detrital feldspars and micas are also altered to kaolinite, and finely disseminated haematite pigment is leached out. Concentration of silica in surface waters is very low.


Type de document :
Article de périodique

Source :
Zeitschrift für Geomorphologie Stuttgart, 1984, vol. 28, n°. 3, p. 321-332, Références bibliographiques : 18 réf.

Date :
1984