Further thoughts on the excess crustal calcium

Abstract

Two topics are examined in this work; the similar relative compositions of the sedimentary lithosphere and of crustal igneous rocks and the problem of the excess crustal calcium. The latter is shown to be due primarily to the biologically mediated conversion of plagioclase feldspars which has been accelerated since the Cambrian and to the trapping of the resultant CaCO₃ on continental shelves.