The video below, from ABC Science, draws some fascinating and surprising conclusions about the origins of Tasmania’s Geology Profile. Ed: Kevin Parker
The rugged coastline of Tasmania is shedding light on Earth’s history. Rocks from this region tell a dynamic story of how the Earth has evolved and reveals an emergent story about Tasmania’s Geology . They depict a world in which continents drift, collide, and split apart. While many are familiar with supercontinents like Pangaea and Gondwana, Tasmania offers a glimpse into an even older supercontinent called Nuna, from the Precambrian era, over a billion years ago.
Geologists Jacqui Halpern and Jack Mulder are on a mission to place Tasmania on the ancient map of Nuna. Their investigative process involves examining the oldest rocks in Tasmania, particularly zircon crystals within them, which function as natural timekeepers. These zircons are key to determining the age of the rocks. By analyzing the ratio of uranium to lead isotopes, they can pinpoint when the zircons were formed. To their surprise, the rocks were about 1.5 billion years old, half a billion years older than previously thought.
Field observations combined with lab data suggest these rocks have origins not just from Australia but also from East Antarctica and North America. This implies Tasmania was once a microcontinent, possibly situated between two larger continents. The current theory suggests that during the era of the Nuna supercontinent, Tasmania might have been located near the North Pole, adjacent to parts of what is now North America and East Antarctica. Over time, plate tectonics drifted parts of Tasmania to collide with the Australian mainland about 500 million years ago.
In essence, the rocks of Tasmania provide crucial information, revealing connections with regions as distant as North America and Antarctica. It challenges our understanding of Earth’s past, demonstrating the dynamic nature of our planet and the ever-changing positions of continents over billions of years.
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