Analysis of these results provide further evidence that chemical weathering, chemical alteration of minerals in marine settings, biogeochemical processes (e.g. sulphate reduction in sediments and biomineralization) and evaporite deposition are important for the geochemical composition of the terrestrial surface on geological time scales. The movement of significant amounts of carbonate to the terrestrial surface is identified as the major process for observed Ca-differences. Because abrupt and significant changes of the carbonate abundance on the terrestrial surface are likely influencing CO 2-consumption rates by chemical weathering on geological time scales and thus the carbon cycle, refined, spatially resolved analysis is suggested. This should include the recognition of the geochemical composition of the shelf areas, now being below sea level.Īlthough the crustal evolution and the processes involved are discussed controversially (e.g. Reymer and Schubert 1984 Rudnick 1995 Albarede 1998 Rudnick and Gao 2003 Hawkesworth and Kemp 2006), major controls of its composition are unanimously identified.
These are the differentiation of igneous intracrustal magmas and intraplate crust growth, continent–continent collision (Rudnick and Gao 2003 Hawkesworth and Kemp 2006 Lee et al.
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