During the Cretaceous period (from 145 to 65 million years ago) the oxygen content in the Earth’s oceans several times dropped to critically low values. The duration of each such period not exceeding one million years.
The disappearance of oxygen led to the extinction of many living creatures. According to one version, the reason for the disappearance of oxygen was volcanic activity. Volcanoes “manure”, the ocean, provoking the mass reproduction of plankton in its upper layers.
Plankton, in turn, serves as food Bacteria somewhat deeper. They are actively propagated and absorbed in the water of oxygen. Without this gas wiped out a lot of living things (about a hundred million years ago, Earth’s oceans lost a third of all deliveries of marine organisms).
To date, scientists have not reached a consensus on exactly how volcanoes “manure” ocean. One hypothesis suggests that the trigger provided the carbon dioxide emitted into the atmosphere during eruptions. He called the greenhouse effect.
The ensuing climate change has led to the fact that the flow of water from melted ice into the ocean washed away the nutrients stimulated the reproduction of plankton.
The creators of the work suggested a different mechanism. Sulfates are not the substance, without which the plankton can not reproduce. However, sulfates are stimulated in the ocean processes that lead to the release of additional phosphate.
Content of phosphates in the water limits the amount of plankton. Additional phosphates triggered a boom of its propagation, which led eventually to the extinction of the oceans.
This is not the first study, which collected evidence of guilt in the death of volcanoes of the ancient inhabitants of the Earth. In summer 2009 a group of scientists has shown that powerful eruptions occurred during one or two million years. During this time in the atmosphere would accumulate enough CO2 to significantly alter the Earth’s climate.