Newswise – An ancient attack of global warming 56 million years ago, when acidified oceans and extinct marine life had a milder effect in the Gulf of Mexico, where life was protected by the unique basin geology – according to research by the University of Texas Institute. for Geophysics (UTIG).
Published in the magazine Marine and oil geologyThe findings not only shed light on ancient mass extinctions, but could also help scientists determine how current climate change will affect marine life and help find oil and gas deposits.
And while the Gulf of Mexico is very different today, UTIG geochemist Bob Cunningham, who led the research, said that valuable lessons about climate change can be drawn today from how the Gulf has been affected in the past.
“This event, known as the Paleocene-Eocene thermal maximum or PETM, is very important to understand because it indicates a very strong, albeit brief, injection of carbon into the atmosphere, which is similar to what is happening now,” he said.
Cunningham and his colleagues studied the ancient period of global warming and its impact on marine life and chemistry by studying a group of mud, sand and limestone found in the Persian Gulf.
They discussed stone fragments from oil and gas extraction and found a number of microfossils from radiolarians – a type of plankton – that surprisingly thrived in the Persian Gulf during ancient global warming. They concluded that a steady supply of river sediments and circulating ocean waters had helped radiolarians and other microorganisms survive, even as global warming had become more hostile to life.
“In many places, the ocean was absolutely uninhabitable for anything,” said UTIG biostratigrapher Marcie Purkey Phillips. “But we don’t seem to see as severe an effect in the Gulf of Mexico as we have seen elsewhere.”
The reasons for this go to the geological forces that were transforming North America at the time. About 20 million years before ancient global warming, the rise of the Rocky Mountains redirected the river into the Northwest Gulf of Mexico – a tectonic shift known as the Laramid Elevation – sent much of the continent’s rivers across present-day Texas and Louisiana into Deeper Bay waters.
As global warming hit and North America became warmer and wetter, rain-filled rivers poured nutrients and sediments into the basin, providing plenty of nutrients for phytoplankton and other food sources for radiolarians.
The findings also confirm that the Gulf of Mexico has remained connected to the Atlantic Ocean and the salinity of its waters has never reached extremes – an issue that has so far remained open. According to Phillips, the very presence of radiolarians – who thrive only in nutrient-rich water, which today is no saltier than seawater – has confirmed that the waters of the Persian Gulf have not been too salty. Cunningham added that the organic content of sediments continued to decrease from the coast, a sign that deep currents driven by the Atlantic Ocean were sweeping the bottom of the basin.
The research accurately dates the closely related geological strata in the Wilcox Group (a set of rock strata that hide an important oil system), a performance that can help find undiscovered oil and gas reserves in formations that are the same age. At the same time, the findings are important for researchers studying the effects of today’s global warming, as they show how water and the ecology of the Gulf have changed during a very similar period of climate change a long time ago.
The study collected geological samples from 36 industrial wells throughout the Gulf of Mexico, plus several scientific drilling expeditions, including the 2016 Chicxulub asteroid impact study led by UT Austin, which led to the extinction of non-bird dinosaurs.
For John Snedden, co-author of the study and lead researcher at UTIG, the study is a perfect example of industry data used to address important scientific issues.
“The Gulf of Mexico is a vast natural archive of geological history that is also being researched very carefully,” he said. “We used this very robust database to investigate one of the highest thermal events in the geological record, and I think it gave us a very fine look at a very important time in Earth’s history.”
Snedden is also the Program Director of UT’s Gulf Basin Depositional Synthesis, an industrially funded project that maps the geological history of the entire Gulf Basin, including current research. UTIG is a research unit of the UT Jackson School of Geosciences.
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