The staff of the Faculty of Biology of Moscow State University named after M. V. Lomonosov, together with Siberian scientists, as well as colleagues from Great Britain and China, found out that over 25 million years the composition of the World Ocean has changed a lot. This is reported in an article published in the journal Geology.
Scientists conducted a study that showed that the predominantly anoxic acidic water column that characterized the World Ocean of the Ediacaran period turned into a water column with a relatively oxygenated upper layer at the beginning of the Cambrian period.
According to the doctor of biological sciences, professor of the biological evolution department of the biological faculty of the university Andrei Zhuravlev, this fact is confirmed by lithological markers, including the presence of abundant primary stoichiometric dolomite marine cement with a high iron content, which is formed in an oxygen-free, predominantly sulfide environment. And also in sediments older than 545 million years and calcite marine cement in the Lower Cambrian sediments.
He also noted that the emergence of abundant skeletal organisms coincides with the borderline of the disappearance of "dolomite" acidic environments and, therefore, with the formation of oxygen-enriched shallow waters.
“The formation of the biomineral skeleton and its organic matrix requires significant energy consumption. It is also impossible without oxygen,”added Andrey Zhuravlev.
It should be noted that in the course of the work, scientists used cathodoluminescence methods, as well as geochemical analysis of elements.
Andrei Zhuravlev emphasized that the scientific value of the study is in understanding the evolution of the ocean, which has changed in the composition of the organisms that inhabited it, as well as in its geochemical composition.