Alteration profonde preglaciaire d'un gneiss a Charlesbourg, Quebec (Canada)

Autor: C.R. De Kimpe, Pierre LaSalle, M. R. Laverdiere
Rok vydání: 1983
Předmět:
Zdroj: Geoderma. 31:117-132
ISSN: 0016-7061
DOI: 10.1016/0016-7061(83)90003-4
Popis: A saprolite derived from a gneiss has been sampled in a fault zone at Charlesbourg, near Quebec city. The weathering largely exceeding 6 m in depth and a till overburden suggest preglacial alteration under warmer climatic conditions. This is further supported by the presence of high (up to 15% ) percentages of crystalline iron oxides (goethite and lepidocrocite). Four different facies were defined in the saprolite. Mineralogical analyses were performed on the clay fractions and the following associations were found: swelling minerals + kaolinite, kaolinite, kaolinite + gibbsite, swelling minerals + kaolinite. The degree of weathering of 2:1 minerals into kaolinite seemed to be related to internal drainage conditions. Cation exchange capacity of the saprolite was adequately explained by the clay and silt fraction contributions.
Databáze: OpenAIRE