‘Memory Cell’ in Northern Ontario Rock Holds Record of Earth’s History
A tiny zircon crystal extracted from a three-billion-year-old rock in northern Ontario is being hailed by Canadian and U.S. scientists as a primordial “memory cell” containing a previously unknown record of the Earth’s early history.The researchers also believe their microscopic time capsule could provide a new tool for testing whether life has ever existed on other planets.
The zircon was extracted from an outcropping of deep-earth rock known as the Kapuskasing Uplift, a rare geological feature near the city of Timmins in which ancient rock that’s normally 30 kilometres below the planet’s surface is exposed.
Led by University of Western Ontario geologist Desmond Moser, a team including scientists from California, Wisconsin and Utah studied the site’s rich supply of zircons – well known as a trusted indicator of a rock layer’s age – and determined for the first time that such crystals also provide reliable data about environmental conditions at the time and place the zircons formed.
Scientists have long believed that this “internal history” of a zircon’s birthplace “would be erased” over the eons, Desmond Moser told Canwest News Service, “but it’s just the opposite. They’ve retained this incredibly detailed history of their own growth.”
In an article published in the latest issue of the journal Geology, Desmond Moser and his colleagues explain how chemical signatures detected in the zircon confirm the presence of oceans on Earth over the 200-million-year stretch of time during which the minute crystal was forming about 2.7 billion years ago.
The cooling of the surrounding rock in which the zircon formed finally ended its long period of growth, sealing inside key information about the state of Canada’s future landmass at that time.
Describing their discovery as a “robust, microcrystalline record of the early genesis of North America,” the researchers say this novel feature of the zircon offers a new way of “reconstructing planetary dynamics” on Earth and other worlds – a kind of litmus test in which zircons recovered from Mars or other planets might yield proof of long-extinct oceans or other tell-tale signs of possible life.
“This research shows that these crystals are incredibly resistant to change and proves for the first time that the growth zones we see inside them contain an accurate record of their movements through and around the Earth,” says Desmond Moser.
“The oldest pieces of our planet are crystals of zircon. These crystals are the memory cells of the Earth, and with our study we can now say they are an accurate recorder of planetary evolution over eons – in the same way that rings on an old growth tree can record changes in a forest over hundreds of years.”
He added that the discovery “provides a new tool for dating the appearance of oceans on other rocky planets like Mars, where Rover results indicate zircon crystals should exist.”
…this post forwarded by Windsor Humanist, Alexander Neil, after a March 4, 2008 article by Randy Boswell over The CanWest News Service