Sediments From Ancient Lake Reveals The Impact Of Climate Change On Early Jurassic Period

Posted: Jan 19 2017, 12:18pm CST | by , Updated: Jan 19 2017, 12:34pm CST, in News | Latest Science News

 

Sediments from Ancient Lake Reveals the Impact of Climate Change on Early Jurassic Period
Early Jurassic lake sediments (black) in the Tarim Basin, China. Credit: Oxford Science Blog
 

New study provides a fascinating insight into how lake environments responded to global climate change millions of years ago

Jurassic period is characterized by some of most incredible forms of life that continue to puzzle paleontologists even today.  It was the age of dinosaurs and giant reptiles living on land while the oceans were dominated by animals like ichthyosaurs, marine crocodiles and sharks.

This diversity and abundance of life always urges researchers to learn more about the prehistoric period and its climate. Much of our understanding of past climate is based on geology, particularly in the study of sedimentary rocks found in the oceans.

In the latest effort, researchers again study sediments found at one of the largest lakes in Earth's history and provide a fascinating insight into the impact of climate change on lake environments millions of years ago. This ancient lake is located in the Sichuan Basin in China. It is more than twice the size of England and almost four times the size of Lake Superior and was formed around 183 million years ago in the Jurassic period.

Previous analysis of organic-rich sediments suggests that intense volcanic activity at certain intervals during the Jurassic era contributed to throw the natural carbon cycle off balance. It increased concentrations of carbon dioxide in atmosphere and reduced oxygen levels in large parts of the ocean, leading to the spike in sea-surface temperature.

New research, however, reveals how ancient lakes responded to climate change and shows that high carbon dioxide levels brought an increased supply of nutrients to these reserviors, which encouraged biological productivity. The era gave rise to the most diverse range of organisms the Earth had yet seen. The higher concentrations of carbon were later preserved in the form of sedimentary deposits in the area, making them look relatively dark.

The study suggests that those lakes in Jurassic period responded to climate change in a similar way as oceans.

“The extreme effects of past climatic changes are not limited exclusively to oceans. By dating the lake sediments to the Early Jurassic (Toarcian) period, we were able to show that large lakes formed and were affected in the same way as oceans during an OAE (ocean anoxic event).” Authors say.

“As the climate warmed, the continents experienced increased rainfall, creating lake reservoirs, which essentially acted like mini-oceans. Lake organisms became more abundant, drawing-down massive amounts of carbon dioxide from the atmosphere, which was eventually deposited into sediments. Overtime, these sediments became source rocks for oil.”

The study, carried out by a team of British researchers, is the first to examine the effects of climate change on lakes.

 

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Hira Bashir covers daily affairs around the world.

 

 

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