Sequeira Braga, M.A., Paquet, H., Begonha, A, 2002 - Weathering of granites in a temperate climate (NW Portugal): granitic saprolites and arenization, Catena, 49, (1-2), pp. 41-56, Artigo Nª PII.S0341-8162(02)00017-6 2002

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Sequeira Braga, M.A., Paquet, H., Begonha, A. (Author) FEUP

Journal

Title: Catena

Vol. 49

Pages: 41-56

ISSN: 0341-8162

Publisher: Elsevier

Scientific classification

FOS: Engineering and technology > Other engineering and technologies

Other information

Abstract (EN): Saprolites or “in situ” weathering products from granitoid rocks of Northwest Portugal were studied by means of X-ray diffraction of their clay fraction and observations of polished thin sections combined with TEM, SEM-EDS microanalyses. Their principal features are: (1) depths of more than 10 m; (2) mean material loss of 40% as calculated by an isovolumetric method; (3) low clay content (mean value 7%) and a high degree of mineralogical evolution. The clay fraction is characterized by a predominance of kaolinite and gibbsite, with subordinate 2:1 minerals (illite, chlorite, vermiculitic mixed-layers, vermiculite). The significance of the secondary minerals in granitic saprolites from Northwest Portugal is compared to published data from Atlantic Europe. This allows the definition of a climatic zonality for weathering products and identifies ‘arenization’ as an important weathering process.

Language: Portuguese

Type (Professor's evaluation): Scientific