The Arctic was an enclosed freshwater lake until about 38 million years ago
5 Jul 2009, 1149 Hrs

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Washington, July 5 An analysis by scientists has suggested that the Arctic was an enclosed freshwater lake until about 38 million years ago, when tectonic activity caused it to undergo a transition to an ocean.

Recent studies have suggested that beginning about 44 million years ago the Arctic underwent a transition from lake to ocean conditions.

On the basis of new evidence from rhenium (Re) and osmium (Os) isotopes in the sedimentary record, Andre Poirier and Claude Hillaire-Marcel from the Universite du Quebec a Montreal, Canada, propose a new chronology of that change.

To trace the Arctic's shift from a freshwater to a marine environment, the researchers analyzed Re and Os concentrations and Os isotope ratios in sedimentary material collected from the Lomonosov Ridge in the Arctic.

Their analysis suggests that the Arctic was an enclosed freshwater lake until about 38 million years ago, when tectonic activity caused the Fram Strait to widen, connecting the Arctic to global ocean circulation and bringing about a fairly rapid transition from lake to ocean conditions.

Previous studies had suggested that the transition from lake to ocean conditions was completed only about 17.5 million years ago, after a 26-million-year hiatus.

The researchers conclude that if the results are confirmed by further studies, they will give scientists a new perspective on the tectonic evolution of the Arctic. (ANI)

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