PHOSPHORITES FORMED BY THE ACTION OF MICROORGANISM

According to their fabric features, Sinian-Cambrian Phosphorites in South China can be classified into three major basic types: micrograined, grained and crust-grained phosphorites, among which the textural component of the crust-grained phosphorite is predominately made up of phosphate crust-grains formed by microorganism. There are six forms of phosphate microorganism found in the phosphate crust-grains; ( 1 ) tube-shaped, ( 2 ) rod-shaped, ( 3 ) fibrous, ( 4 ) microglobal, ( 5 ) clumping, ( 6 ) tricuspid. All of them not only have distinct form features of microorganism,but also remain important organic components-amino acid and nucleic-acid-of organic tissues in their fossils. It is known that phosphorus, as a basic nutrient, is so necessary for the growth of all microorganism that none of them would not depend on it. Phosphorus is a structural element of enzymes, adenosine triphosphate, ribonucleic acid, desoxyri-bonucleic acid,nucleic acid and phospholipids,from which cell membranes are made. Microorganism plays a very important role in the circle of phosphorus on the earth. It is the microorganism action that is an important link in the circle of 'phosphorus in the ocean for the concentration of phosphorus to form ore deposits. Recent year studies on liquid crystal materials hane convinced the author that consideralle physiological behaviors of phosphorus-thirsty microorganism, i. e. the preferential extraction, accumulation and transportation of phosphates, may be attributed to the liquid crystal form of the tissues and cells of phosphorus-thirsty microorganism