The effect of Earth's orbit on ancient microorganisms is discovered in a study.

Curtin University researchers studying molecular fossils or "biomarkers" from deep beneath the Chicxulub impact crater discovered evidence of how microorganisms changed in response to changes in the Earth's climate, providing clues about how the planet and life forms may respond to climate change in the modern world.

Credit: Pixabay/CC0 Public Domain
Credit: Pixabay/CC0 Public Domain

Dr. Danlei Wang, a Curtin Ph.D. graduate from the WA-Organic and Isotope Geochemistry Center (WA-OIGC), said that variations in the Earth's orbit around the sun over thousands of years have been known to cause changes in our planet's climate and environment.

"The Early Eocene Climatic Optimum (EECO) about 50 million years ago, which was the warmest period in the past 65 million years, has been linked to our planet's orbital cycles around the sun," Dr. Wang explained.

"We conducted geochemical studies on a sediment core recovered from the Chicxulub crater in the Gulf of Mexico, including biomarker analysis, to learn how microbial ecosystems responded to Earth's orbital cycles near the end of the EECO. The study of astronomically driven climate cycles within sedimentary deposits, known as cyclostratigraphy, was carried out in collaboration with Kiel University."

"Our research discovered that orbital cycles that control Earth's climatic variations like rainfall and terrestrial run-off cause changes in microbial communities, the onset of algal blooms, and ocean stagnation, including toxic conditions at the Chicxulub site."

John Curtin Distinguished Research Fellow, ARC Laureate Fellow The study, according to Professor Kliti Grice, Director of WA-OIGC, was the highest-resolution molecular-level geochemical study ever undertaken to provide evidence of a link between variations in the Earth's orbit and the effect of this on ancient environments preserved in rock record at the end of the EECO period.

"What we discovered near the Chicxulub site at the end of the EECO cycle could have happened elsewhere around the world at other times during the Paleogene period, which spanned about 43 million years and included the EECO," Professor Grice explained.

"Moreover, geologic records containing such orbital-driven geochemical signals from a 'greenhouse' period in Earth's history can provide clues to predict how environments and life may respond to future climate change."

The authors are also associated with Curtin's flagship Earth Sciences research institute, The Institute for Geoscience Research (TIGeR).

Journal information: Earth and Planetary Science Letters


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