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Link between climate change and Gibraltar Currents over 6 million years discovered

Examination of core samples extracted off the coast of Spain and Portugal shows definite proof of shifts in climate change since about six million years ago, and also provides new evidence of a deep-earth tectonic pulse in the region, according to a team of international scientist that includes Carl Richter, a School of Geosciences researcher.

Richter is one of 35 scientists from 14 countries who participated in Integrated Ocean Drilling Program Expedition 339. From November 2011 to January 2012, they worked on board "JOIDES Resolution," a research vessel. The team’s findings were published in the June 13, 2014 issue of "Science" magazine.

Working on board the research vessel JOIDES Resolution, the team took core samples from a three-mile stretch near the Strait of Gibraltar, which is a gateway between the Atlantic Ocean and the Mediterranean Sea. They then examined the sedimentary record produced there by strong ocean currents, commonly called Mediterranean outflow water through the Gibraltar gateway.

“Our initial goal was to understand how the Strait of Gibraltar acted first as a barrier and then as a gateway over the past 6 million years as the currents passed through the area,” Richter said. “Because the Mediterranean outflow water is saltier and heavier than the Atlantic waters, it plunges more than 3,000 feet downslope, carving deep-sea channels, and building up mountains of mud in these unique underwater landscapes. We now have first results for understanding the history of these currents through the Gibraltar gateway.”

Richter said the sediments collected during the expedition indicate that “oceans and climate are closely linked.”

Further analysis showed that the sediments contained far more sand than expected. A sheet of sand extends about 60 miles from the Gibraltar gateway; it is evidence of the strength and velocity of Mediterranean currents.
The research team’s findings could impact future oil and gas exploration, according to the geologist.

“The thickness, extent, and properties of these sands make them an ideal target in places where they are buried deeply enough to allow for the trapping of oil and gas,” he said.
The research team’s abstract notes: “These sands represent a completely new and important exploration target for potential oil and gas reservoirs.”

Expedition 339 was funded by the U.S. National Science Foundation and implemented by the Integrated Ocean Drilling Program – U.S. Implementing Organization.