A Geochemical View of Weathering and the Origin of Sedimentary Rocks and Natural Waters

Abstract

The geochemistry of weathering plays a major role in determining the general composition of sedimentary rocks and natural waters. Chemical weathering converts igneous rocks to the chemical and mineralogical constituents of both clastic and chemical sedimentary rocks, as shown in a newly developed diagram that additionally illustrates the chemical ancestry of carbonate rocks in mafic igneous rocks. New variation diagrams illustrate the chemical differentiation of various sedimentary rocks from average igneous rocks, in which the degree of differentiation depends on previous reactions in chemical weathering. Chemical weathering also modifies surface waters by donating the dissolved solids, especially bicarbonate, dictated by weathering reactions. This interplay of weathering and freshwater chemistry, combined with subsequent chemical and biological deposition from the oceans, illustrates the linkage of the rock and water cycles from rainfall to weathering to transport of dissolved solids to deposition to ev...