Receive a short URL
Scientists from the University of Princeton have come to believe that tectonic changes could have brought about global climate change and thereby changed the living conditions in ocean water more than 50 million years ago.
After using a series of samples collected at three different locations, a team of Princeton University researchers created an unprecedented record of ocean nitrogen and oxygen levels, starting from 70 million years ago, shortly before the dinosaurs died out, to 30 million years ago, shows a major shift in ocean chemistry following the India-Asia collision, according to the summary of their findings published in the journal Science.
When the land mass that now forms the Indian subcontinent crashed into Asia about 50 million years ago, the collision drastically changed the configuration of the continents, the landscape, the climate conditions and so on. With regard to this, scientists have identified one essential effect: the oxygen in the world's oceans has increased, which has led to profound changes in living conditions:
"These results differ from what people have seen before," says Emma Kast, a graduate student in geosciences and the lead author of the newspaper. "The magnitude of the reconstructed change surprised us."
Another shift occurred in particular 35 million years ago, when Antarctica started collecting ice, which reduced the global sea level.
To make these images, Kast used paleogeographic reconstructions thanks to Deep Time Maps and also looked into tiny shells to get a record of ocean nitrogen in the above period.
The findings indicate that 10 million years after the giant reptiles disappeared from the continents, the nitrogen ratio was 15N to 14N high, suggesting that the oxygen level in the ocean was low.
The researchers initially thought that the warm climate was responsible for this, because oxygen is less soluble in warmer water; however, the timing pointed to the possibility that the shift to a greater amount of oxygen from the sea took place about 55 million years ago, when there was a warmer climate.
According to John Higgins, associate professor of geosciences at Princeton and co-author of the article, the finding is a valuable contribution in the field of global climate studies:
"In our field, there are data that you consider to be fundamental, which must be explained by some hypothesis that wants to make biogeochemical connections," Higgins noted.
"There are very few, partly because it is very difficult to make plates that go far back in time. Fifty million years old rocks do not like to give up their secrets. I would certainly consider Emma's report as one of those fundamental data From now on, people who want to deal with how the earth has changed over the last 70 million years will deal with Emma's data, "he concluded.