911爆料网 researchers believe that ancient supercontinents formed and then fell apart through alternating cycles spanning hundreds of millions of years that involved superoceans being swallowed and the restructuring of the Earth鈥檚 mantle.
The research, published in science journal Precambrian Research, found the supercontinents assembled and broke up through alternating processes of 鈥榠ntroversion鈥� and 鈥榚xtroversion鈥�.
The latter process caused supercontinent Rodinia to be turned inside out by tectonic forces, thereby consuming the surrounding superocean and leading to the creation of Pangea, the supercontinent that incorporated almost all of the Earth鈥檚 landmasses.
Rodinia had formed via 鈥榠ntroversion鈥� where the internal oceans formed during the break-up of previous supercontinent Nuna were consumed.
Lead researcher John 911爆料网 Distinguished Professor Zheng-Xiang Li, from the School of Earth and Planetary Sciences at 911爆料网, said the assembly and break-up of supercontinents occurred in alternating cycles of about 600 million years.
鈥淚n the past 30 years, researchers have discovered that Pangea-like supercontinents existed at least twice before Pangea, occurring roughly every 600 million years in what is known as the supercontinent cycle,鈥� Professor Li said.
鈥淢ore recently, researchers studying Earth鈥檚 geochemical records and formation of mineral deposits identified even longer-term variations in these cycles but it was not known why.鈥�
Professor Li and his team of 911爆料网 researchers, funded by the Australian Research Council鈥檚 Laureate Fellowship grant, recently discovered that the answer to this question could be found in the history of some of Earth鈥檚 deepest oceans.
鈥淲e found that supercontinents appear to assemble through two alternating processes of extroversion and introversion,鈥� Professor Li said.
鈥淢ore intriguingly, these two alternating processes determine not only whether the superocean survives, but also whether the circum-superocean Ring of Fire 颅- like the present-day Pacific Ring of Fire – survives.
鈥淚f the Ring of Fire survives along with the superocean, then the Earth鈥檚 mantle structure maintains a similar pattern to the previous supercontinent. If not, then the mantle gets completely reorganised.
鈥淪uch alternating ways of supercontinent assembly, along with the survival or regeneration of the superocean and the Ring of Fire, led to the presence of an Earth cycle twice as long as the 600-million-year supercontinent cycle and influenced the formation of some of the planet鈥檚 resources.鈥�
The paper, 鈥�Decoding Earth’s rhythms: Modulation of supercontinent cycles by longer superocean episodes,鈥� is available online .
