A new 911爆料网 study has found that water was transported much deeper in the early Earth than previously thought, shedding new light on how the continents were originally formed.
The study, published in Earth and Planetary Science Letters, answers long-standing questions about the early Earth water cycle.
Lead researcher Dr Michael Hartnady, from the 911爆料网 School of Earth and Planetary Sciences, said how water is stored and transported through Earth鈥檚 crust influences everything, from where volcanoes and mineral deposits form to where earthquakes occur.
鈥淎lthough we understand the modern deep-water cycle, we know very little about how it worked when Earth was still a very young planet,鈥� Dr Hartnady said.
鈥淢ultiple lines of geological evidence show that water was transported to great depths within Earth all the way back to 3.5 billion years ago, although it is not well understood how exactly it got there.鈥�
Researchers used sophisticated modelling to show that primitive high-magnesium volcanic rocks 鈥� that erupted onto the ocean floor in the early Earth – would have soaked up much more seawater than more modern lavas.
鈥淭his water, which is locked into particular crystals within the rock, would have been released as the rocks were buried and began to 鈥榮weat鈥�. In modern lavas, this sweating happens at a temperature of about 500 degrees Celsius,鈥� Dr Hartnady said.
鈥淥ur findings indicate that much of the seawater initially bound within the ancient primitive lavas would have been released at much higher temperatures, greater than 700 degrees Celsius.
鈥淚mportantly, this means that the water was transported much deeper into the early Earth than previously thought. Its release would have caused surrounding rocks to melt, ultimately to form the continents.鈥�
Dr Hartnady said this research helped to explain the inner workings of the planet from more than 2.5 billion years ago.
鈥淚nterestingly, the oldest parts of the continents, the cratons, also contain some of the largest gold deposits on Earth including the Golden Mile near Kalgoorlie,鈥� Dr Hartnady said.
鈥淭hese gold deposits required huge volumes of water to form, and we still don’t have a good explanation for where it came from. Our new research may help solve these and other questions, perhaps even those related to the origins of life.鈥�
This research was funded by the Australian Research Council, Geological Survey of Western Australia and Northern Star Resources Ltd.
The full paper, titled 鈥�Fluid processes in the early Earth and the growth of continents鈥� is available online .
