2 QUT researchers used a basic laptop and a piece of rock from a diamond mine waste pile to solve a long-standing geological puzzle about diamond formation in the Earths ancient continents.
2 researchers from Queensland University of Technology (QUT) have utilized a simple laptop computer and a piece of rock, obtained from a diamond mines “waste pile”, to unwind an enduring geological mystery surrounding the formation of diamonds in the deep roots of the earths ancient continents.
The lead author, QUT Ph.D. trainee Carl Walsh, in addition to QUT Professor Balz Kamber and Emma Tomlinson from Trinity College, Ireland, recently published their findings in the distinguished journal Nature.
Mr. Walsh stated the study, for his MSc research, involved computer system modeling on a rock from the African continent recuperated from the bottom of the lithosphere, the outer part of the Earth in between about 30km and 250km below the surface. Mr. Walsh said the dominant part of a continent was the part that you never see.
” If you consider an iceberg– the visible part– if you simply had an iceberg floating on the ocean surface area it would topple like a boat. This is like the keel of an iceberg,” Mr. Walsh said.
Carl is looking at a cube of garnet peridotite. The color of this garnet shows the presence of chromium, which is an indication of the existence of diamond.
” We generally had a known starting composition of a rock, which is representative of the earths mantle at an early time in the history of the earth before all the continents were formed,” Mr. Walsh said. “We took that starting structure and modeled what would take place to it if it was gradually melted, and what would be left over. And that material is what forms the bulk of the roots of ancient continents that are still around today.”
Teacher Kamber, from QUTs Faculty of Science, School of Earth and Atmospheric Sciences, said the goal of this research study was to use a computer model to see how these deep roots may have formed.
” The design basically predicts which minerals and melts will be present as you alter the temperature of the mantle. So, its a predictive tool you can compare to the structure of real minerals and rocks,” Prof Kamber said.
The piece of rock used for the innovative computer system modeling was mined at some point between 1871 and 1914 and wound up in the “waste pile” of the legendary Kimberley diamond mine, best referred to as The Big Hole– a mix open-pit and underground mine– in Kimberley, Northern Cape in South Africa.
Professor Balz Kamber and QUT Ph.D. trainee Carl Walsh. Credit: Queensland University of Technology
The piece of rock they have designed, garnet harzburgite, was given the surface in a kimberlite pipe. The rock was obtained by Professor Kamber– who specializes in petrology, a branch of geology that studies rocks and the conditions under which they form.
He carefully sledgehammered the rock down to a size that he might successfully deliver home.
” It contains an assortment of minerals that were entrained en route up as they ripped through the base of the entire continent in a supersonic volcanic eruption– the likes of which we have never ever seen,” Professor Kamber said. “The minerals in this rock sample are so severely harmed, they are yelling still today, they were absolutely smashed.”
” It is so exciting to see this maintained, it is incredibly old– 3.3 billion years old. Probably the earliest rock many people will ever hold in their hands,” Professor Kamber stated.
Mr. Walsh said the research study fixed the quandary of diamonds and the temperatures in which they formed, provided a diamond will develop into graphite if warmed up too much.
” But yet, when we look at the rocks that consist of diamonds, they need to have been warmed to enormous temperature levels,” Mr. Walsh said. “So why is it that it is precisely those rocks that experienced the greatest temperature levels that wound up having diamonds?”
Their research challenges the existing two-step shallow “melting and stacking” description.
” Previously, it was thought that the majority of the ancient deep roots of continents would have been host to diamonds which these diamonds were damaged in time, since the base of the continent is continuously gotten into and deteriorated by volatile-rich melts and fluids,” Mr. Walsh said. “Our work suggests that in fact, this might not be the case, that diamonds are uncommon today– and remained in reality always unusual. And thats since we can for the very first time know what is missing out on from the cradle of the diamond and we can go hunt for it at the surface.”
Professor Kamber said on the contemporary earth the heat and temperature level distribution in the mantle is not consistent.
” We have locations of reasonably uniform mantle temperature and areas where the mantle is a lot hotter. These are called mantle plumes. And we have expressions of these in Hawaii and Iceland,” Professor Kamber said. “What were studying is the effect of ancient plumes– when much hotter plumes than we have now would have struck the base of a growing continent.”
Because carrying out the research study, Mr. Walsh has actually traveled to Canberra to recreate comparable rocks in the laboratory at the Research School of Earth Sciences at the Australian National University.
Referral: “Deep, ultra-hot-melting residues as cradles of mantle diamond” by Carl Walsh, Balz S. Kamber and Emma L. Tomlinson, 15 March 2023, Nature.DOI: 10.1038/ s41586-022-05665-2.
The color of this garnet reveals the existence of chromium, which is an indication of the existence of diamond.” We basically had a known beginning composition of a rock, which is representative of the earths mantle at an early time in the history of the earth before all the continents were formed,” Mr. Walsh stated.” Previously, it was believed that most of the ancient deep roots of continents would have been host to diamonds and that these diamonds were damaged over time, because the base of the continent is continuously attacked and deteriorated by volatile-rich melts and fluids,” Mr. Walsh said. “Our work recommends that actually, this may not be the case, that diamonds are uncommon today– and were in reality constantly unusual. And thats since we can for the first time know what is missing from the cradle of the diamond and we can go hunt for it at the surface.”
