SERPENTINIZAÇÃO E METASSOMATISMO EM ROCHAS ULTRAMÁFICAS: DISCUSSÃO DAS CARACTERÍSTICAS E RECOMENDAÇÕES PARA O TRATAMENTO GEOQUÍMICO

Abstract

This paper intends a general revision about the petrochemical aspects of the ultramafic rocks metamorphic modification. At first, the extreme mechanisms of mass transfer is distinguished: intergranular diffusion and transport by solution; their relative importance depends on the water content of the system. The geological conditions in which the mass transfer occurs are described as contact/juxtaposition, or as infiltration, and available literature examples are also presented. The geological features used to recognize the mechanisms and the conditions of the mass transfer include metasomatic zoning, structures, chemical components mobility, mineral phase stability etc, and they are discussed in the paper. At last, based on the results of experimental investigations, a method is developed to verify which chemical components were transfered during the serpentinization and metasomatism of the ultramafic rocks. The method is developed to put in evidence the elements that do not develop chemical potencial gradients.