Chemical balance of the Earth's crust

Abstract

The chemical composition and lithologic proportions of average sedimentary and igneous rocks are analyzed by a linear least squares regression. The best set of internally consistent data for sediments in geosynclines, continental platforms, deep ocean basin and the average igneous and sedimentary rock are shown below. These results are based on published estimates of the chemical composition of igneous and sedimentary rocks and the relative volume of sediments on the continents and in the deep ocean basins. SiO 2 A1 2O 3 Fe(total) MgO CaO Na 2O K 2O CO 2 Geosynclines 55.2 12.0 3.6 3.2 8.3 1.0 2.4 8.6 Platforms 49.5 10.7 3.2 3.3 12.3 0.9 2.2 10.8 Av. sed. 55.9 13.8 4.4 3.6 5.8 1.2 2.6 5.2 Av. ig. 59.0 15.0 5.0 3.6 7.0 3.4 3.2 The lithologic proportions are: geosyncline—24% sandstone, 58% shale, and 16% carbonate; platform—23% sandstone, 49% shale and 26% carbonate; average sedimentary rock—13% sandstone, 33% shale, 12% carbonate, and 41% pelagic; average igneous rock is approximately 2/3 granodiorite and 1/3 tholeiite. These data indicate a chemical balance of major elements in the Earth's upper crust during the last 1.5 b.y.