Thursday, May 21, 2015

Geological goldmine uncovered after Tasmanian lake drained

A view of the southern half of Lake Rowallan shortly after it was drained in late February.

1 billion year old Precambrian sedimentary rocks exposed at Lake Rowallan that were deformed and metamorphosed during the Cambrian collision (510 million years ago).

By Emilie Gramenz

Geologists have been taking advantage of a "once in a lifetime" opportunity to study ancient rock formations after a lake in the Tasmania's north was drained to reveal a Precambrian site.

Hydro Tasmania's Lake Rowallan, east of Cradle Mountain, was drained earlier this year as part of an upgrade to the Rowallan power station.

The Precambrian rock formations that were exposed are about one billion years old and have not been visible in 20,000 years.

University of Tasmania researcher Dr Rob Scott said the formations were last exposed during the ice age.

"The Precambrian rocks exposed... are [the result of] arguably the biggest and most significant geological event to have ever affected the state," he said.

Dr Scott said geology researchers were studying the deformation and metamorphic history of the rocks.

"What we can learn in Tasmania has implications for the geological development of the whole of eastern Australia at this time, but we have the advantage of being able to obtain hard data to help us understand exactly what happened," he said.

The Precambrian era - the earliest geological age - covers the bulk of Earth's history.

Scientists have only a small window to study the Lake Rowallan formations with Hydro Tasmania planning to refill the lake when upgrades to its infrastructure are complete.

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