ANALYSIS OF THE GENESIS OF NODULAR PHOSPH ORITES BASED ON ORGANIC-MATTER INVESTIGATION (BY EXAMPLE OF THE CAMBRIAN KUONAMKA FORMATION, SIBERIAN PLATFORM)

The results of analysis of organic matter from nodular phosphorites an d their host bituminous argillites of the Lower-Middle Cambrian Kuonam ka Formation of the Siberian Platform are given. The organic matter of the former and latter formations have been distinguished to be of sim ilar, mainly plankton-derived nature. However, the organic matter from phosphorites is characterized by some specific features (enhanced con tent of organic sulfur, lesser value of hydrogen index, lower concentr ation of paramagnetic centers, peculiarities of saturated hydrocarbon content) interpreted as the result of later microbial activity which i s consistent with the final stages of phosphate genesis.