MAIN CAUSES OF PHOSPHERITE-ACCUMULATION EPOCHS IN THE EARTH'S HISTORY

Abstract

Regularities in the distribution of apatites and apatite-bearing igneous rocks are compared with phosphorite-accumulation epochs. It is shown that periods of maximal phosphate accumulation result from erosion and weathering of magmatogenic apatite accumulations on land and increased P 2O 5 supply into adjacent paleoseas. The hypothesis of the hydrothermal-volcanogenic origin of phosphorites is critically revised.