The earliest rocks in our Solar System were more like candy floss than the hard rock that we know today, according to research published today in the journal Nature Geoscience.
The work, by researchers from Imperial College London and other international institutions, provides the first geological evidence to support previous theories, based on computer models and lab experiments, about how the earliest rocks were formed. The study adds weight to the idea that the first solid material in the Solar System was fragile and extremely porous – much like candy floss – and that it was compacted during periods of extreme turbulence into harder rock, forming the building blocks that paved the way for planets like Earth.
Dr Phil Bland, lead author of the study from the Department of Earth Science and Engineering at Imperial College London, says:
"Our study makes us even more convinced than before that the early carbonaceous chondrite rocks were shaped by the turbulent nebula through which they travelled billions of years ago, in much the same way that pebbles in a river are altered when subjected to high turbulence in the water. Our research suggests that the turbulence caused these early particles to compact and harden over time to form the first tiny rocks."
The researchers reached their conclusions after carrying out an extremely detailed analysis of an asteroid fragment known as a carbonaceous chondrite meteorite, which came from the asteroid belt between Jupiter and Mars. It was originally formed in the early Solar System when microscopic dust particles collided with one another and stuck together, coalescing around larger grain particles called chondrules, which were around a millimetre in size.
To analyse the carbonaceous chondrite sample, the team used an electron back-scatter defraction technique, which fires electrons at the sample. Researchers observe the resulting interference pattern using a microscope to study the structures within. This technique enabled the researchers to study the orientation and position of individual micrometre-sized grain particles that had coalesced around the chondrule. They 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.
The team also defined a new method to quantify the amount of compression that the rock had experienced and deduce the rock's original fragile structure.
Dr Bland adds: "What's exciting about this approach is that it allows us – for the first time – to quantitatively reconstruct the accretion and impact history of the most primitive solar system materials in great detail. Our work is another step in the process helping us to see how rocky planets and moons that make up parts of our Solar System came into being."
In the future, the team will focus further studies on how the earliest asteroids were built.
This research was funded by the Science and Technology Facilities Council.
Notes to Editors:
1. "Earliest rock fabric formed in the Solar System preserved in chondrule rim" Nature Geoscience, Sunday 27 March 2011.
The full listing of authors and their affiliations for this paper is as follows:
Philip A. Bland [1,2,3], Lauren E. Howard [2], David J. Prior [4], John Wheeler [5], Robert M. Hough [6] and Kathryn A. Dyl [1]
[1] Impacts and Astromaterials Research Centre (IARC), Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK [2] IARC, Department of mineralogy, Natural History Museum, London SW7 5BD, UK [3] Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth Western Australia 6845, Australia [4] Department of Geology, University of Otago, 360 Leith Walk, PO Box 56, Dunedin, Otago 9054, New Zealand [5] Department of Earth and Ocean Sciences, University of Liverpool, 4 Brownlow Street, Liverpool L69 3GP, UK [6] CSIRO Earth Science and Resource Engineering, 26 Dick Perry Avenue, Kensington, Perth Western Australia 6151, Australia
2. About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.
Website: www.imperial.ac.uk
Journal
Nature Geoscience