A Curtin researcher and team of experts from around the world have discovered that the earliest rocks in our Solar System are more like candy floss than the hard rock we know today.
Published recently in the journal Nature Geoscience, the Science and Technology Facilities Council funded research, conducted by scientists at Curtin University, CSIRO, Imperial College London, the University of Liverpool and the Natural History Museum in London, provided the first geological evidence to support theories about how the earliest rocks were formed.
Lead author of the study, Adjunct Professor Phil Bland, of Curtin University’s Department of Applied Geology, said the study added weight to the idea that the first solid material in the Solar System was fragile and extremely porous, much like candy floss.
“This material compacted during periods of extreme turbulence into harder rock, forming the building blocks to pave the way for planets like the Earth,” Professor Bland said.
“Much in the same way that pebbles in a river are altered when they are subjected to periods of high turbulence in water, our study makes us even more convinced that the same thing happened to the early carbonaceous chondrite rocks, as they travelled through the turbulent nebula billions of years ago.
“However, rather than smoothing their surface, as in the case of a pebble, our research is helping us to see that periods of high turbulence caused the dust to compact and harden over time to form these first tiny rocks.”
Professor Bland said the findings came after researchers carried out an extremely detailed analysis of a fragment of an asteroid, known as a carbonaceous chondrite meteorite, which had come from the asteroid belt between Jupiter and Mars.
“These rocks were originally formed in the early Solar System when microscopic dust particles collided with one another, sticking together and coalescing around larger grain particles called chondrules, which were around a millimetre in size,” he said.
According to Professor Bland, the approach used to analyse the sample could open up a number of new areas of research.
“We used an electron back-scatter diffraction technique, which fires electrons at the sample so that researchers can observe the resulting interference pattern using a microscope in order to study the structures within,” he said.
“This technique enabled us to study the orientation and position of individual micrometre-sized dust particles that had coalesced around the chondrule.”
The team found that the grains coated the chondrule in a uniform pattern, which they deduced could only occur if this tiny rock was subjected to shocks in space, possibly during these periods of turbulence.
Professor Bland said the new method would allow researchers, for the first time, to quantitatively reconstruct the accretion history of the most primitive solar system materials in great detail.
“Our work is another step in the process that is helping us to see how the rocky planets and moons that make up parts of our Solar System came into being” he said.
Professor Bland said the research team would next focus on how the earliest asteroids were built.
Professor Philip Bland
Adjunct Professor, Dept of Applied Geology, West Australian School of Mines
Andrea Barnard, Public Relations, Curtin University
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