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Mineralogical norm calculations applied to tropical weathering profiles

Published online by Cambridge University Press:  05 July 2018

G. Voicu ,
M. Bardoux  and
D. Voicu
G. Voicu
Affiliation:
Département des Sciences de la Terre, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal (Québec), Canada, H3C 3P8
M. Bardoux
Affiliation:
Département des Sciences de la Terre, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal (Québec), Canada, H3C 3P8
D. Voicu
Affiliation:
Département d'Informatique, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal (Québec), Canada, H3C 3J7
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Abstract

In contrast with igneous and metamorphic rocks, classical petrochemical calculation methods cannot be used for tropical weathering components (saprolite, bauxitic, ferruginous, siliceous and calcareous laterite) in converting whole-rock chemical analyses into normative mineralogical weight percentages. Weathering profiles are characterized by a mixture of primary and secondary minerals, which are not considered in the classical methods of mineralogical norm calculation. A new petrochemical calculation algorithm is proposed for the conversion of whole-rock chemical analyses into weathering norm (WN) for several components of the tropical weathering profiles. The normative minerals are represented by three primary minerals, six secondary minerals, four primary/secondary mineral pairs, and five minerals which can have both primary and secondary origin. This algorithm has been used in MINNOR, a WINDOWS application written in Visual Basic, which calculates the mineralogical norm. In order to test the program, several types of different chemical weathering profiles from South America and Africa have been selected. Special attention is paid to the weathering profile from Omai, Guyana, South America.

Keywords

mineralogical normwhole-rock analysestropical weathering profilecomputer program
Type
Petrology
Information
Mineralogical Magazine , Volume 61 , Issue 405 , April 1997 , pp. 185 - 196
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1997

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