Washington: Researchers analyzed modern and fossil plant resins to reconstruct the composition of the Earth`s atmosphere of the last 220 million.
The results suggest that atmospheric oxygen was considerably lower in the Earth`s geological past than previously assumed.
This new study questions some of the current theories about the evolution of climate and life, including the causes for the gigantism of dinosaurs.
Some of the few organic materials that may preserve reliable data of the Earth`s geological history over millions of years are fossil resins (e.g. amber).
Ralf Tappert from the Institute of Mineralogy and Petrography at the University of Innsbruck, said that compared to other organic matter, amber has the advantage that it remains chemically and isotopically almost unchanged over long periods of geological time.
The mineralogist and his colleagues from the University of Alberta in Canada and universities in the USA and Spain have produced a comprehensive study of the chemical composition of the Earth`s atmosphere since the Triassic period.
The research team analyzed a total of 538 amber samples from from well-known amber deposits worldwide, with the oldest samples being approximately 220 million years old and recovered from the Dolomites in Italy.
The team also compared fossil amber with modern resins to test the validity of the data. The results of this comprehensive study suggest that atmospheric oxygen during most of the past 220 million years was considerably lower than today`s 21 percent.
Tappert said that they suggest numbers between 10 and 15 percent.
These oxygen concentrations are not only lower than today but also considerably lower than the majority of previous investigations propose for the same time period.
The study has been published in the journal Geochimica et Cosmochimica Acta.
