New data revealing two tectonic plates fused to form Antarctica 15 million years later than originally predicted could have major implications for understanding tectono-volcanic activity from New Zealand to California, according to a BGU researcher.
In a study published in the August edition of Nature Communications, Dr. Roi Granot (pictured left) of BGU's Department of Geological and Environmental Sciences, and Dr. Jérôme Dyment from the Institut de Physique du Globe de Paris, CNRS, present marine magnetic data collected near the northern edge of the West Antarctic rift system that shows motion between East and West Antarctica, which was assumed to have ended abruptly 26 million years ago, actually continued for another 15 million years.
“Since Antarctica connects the Pacific plate to the rest of the world, these results have important ramifications for understanding the tectonic evolution around the Pacific Ocean – the rise of New Zealand's Alpine Mountains, motions along the San Andreas Fault in California, and more," says Dr. Granot.
Over 200 million years ago, a rift bisected Antarctica. The motion of eastern and western tectonic plates that drifted along the length of this rift created one of the longest mountain ranges in the world (the Transantarctic Mountains). It also caused the eruption of hundreds of volcanoes, mostly under the ice sheets, and shaped the sub-ice topography. These motions dictated, and still dictate, the heat flow rate that the crust releases under the ice and is one of the factors controlling the rate that chunks of ice break off glaciers and fall into the water to form icebergs.
GPS data and a lack of seismic activity suggest that the rift in Antarctica is no longer tectonically active. According to the researchers, until now the unanswered question was: How did the plates drift against each other over the last 26 million years and when did the rift stop being active?
The new marine geophysical data recorded during two excursions on a French icebreaker enabled Drs. Roi Granot and Jérôme Dyment to date the ocean floor and calculate the relative motion between the Antarctic plates and the Australian plate.
“Antarctica forms an important link between Pacific and Indo-Atlantic global plate tectonic circuits. Understanding past plate motions between East and West Antarctica affects our ability to accurately predict the kinematic evolutions of other plate boundaries," says Dr. Granot. “Incorporating the new Antarctic plate motion data into the global plate circuit will have major implications for predicting the motion of the Pacific plates in relation to others around the world."
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