Genesis of Microgranular Phosphorites

摘要

Approximately 540 Ma B.P., the geological history of the Earth was marked by very important events—the input of a huge amount of phosphorus [1] and its involvement in the geochemical cycle of the World Ocean. In the Tommotian Age of the Lower Cambrian, nearly all sediments of the Earth were contaminated with phosphorus. Moreover, this age was characterized by the formation of the superlarge phosphate-bearing provinces of the world (Malyi Karatau, Khubsugul, Yunnan, and others). These events coincide with the large-scale appearance of skeletal fauna. Therefore, the elucidation of the genetic relation between bios and phosphates is of great scientific interest. Stratified deposits of microgranular phosphorites that appeared first in the Tommotian Age are also known in the Permian Phosphoria Basin. Such phosphorites are composed of rounded microparti-cles and oolites or pellets. Researchers have proposed two antagonistic (chemogenic and biogenic) concepts of the formation of pellets. According to the chemogenic concept, nearly all pellets are oolites, and they should be considered a form of coagulation of colloidal matter. According to the organogenic concept, pellets are related to the vital activity of various organisms (mainly, bacteria and algae).