Â鶹ֱ²¥ researchers have for the first time been able to visualise where helium atoms are trapped within individual mineral grains, providing information that can help to determine the geological history of the Earth\u2019s crust and assist in monitoring natural hazards like earthquakes and volcanic eruptions.<\/p>\n
The researchers, led by Professor Brent McInnes of Curtin\u2019s John de Laeter Centre, teamed up with Canberra-based high-technology instrument manufacturer ASI Pty Ltd to create a new laser microanalysis instrument, the RESOchron\u2122, capable of measuring helium at high resolution \u2013 to one-tenth the width of a human hair.<\/p>\n
Dr Martin Dani\u0161\u00edk, lead author of a paper on the research published in Science Advances, said helium \u2212 generated over long periods of time in uranium and thorium-bearing mineral crystals \u2212 was a highly sought-after commodity used in medical and industrial applications. It has also been used by geoscientists to date rocks.<\/p>\n
\u201cScientists have been using the helium dating technique to determine the age of minerals for over 100 years, but until now, nobody has been able to observe the actual distribution of helium within the crystal structure,\u201d Dr Dani\u0161\u00edk said.<\/p>\n
Dr Dani\u0161\u00edk said that by using the RESOchron to repeatedly raster a laser across a zircon crystal\u2019s surface, the team was able to create the first helium abundance map.<\/p>\n
\u201cWe then used numerical simulations to determine how thermal events in the Earth\u2019s crust influenced helium abundance patterns in the crystal over geological time,\u201d Dr Dani\u0161\u00edk said.<\/p>\n
\u201cBy matching measured and simulated helium distributions, we were able to decipher the mineral\u2019s geological history.\u201d<\/p>\n
[youtube]http:\/\/www.youtube.com\/watch?v=O1kMei_JLCE[\/youtube]<\/p>\n
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\nProfessor McInnes, who conceived the instrument concept and assembled the project team, said the ability to measure radiogenic helium distributions in individual grains could help scientists understand more about the timing of fault movement, volcanic eruptions and mountain building processes, as well as assist in the exploration for mineral and petroleum deposits.<\/p>\n
\u201cWe were surprised to discover extremely high concentrations of helium in cavities within crystals, and speculate that this could be useful in earthquake monitoring, because the crushing of minerals during fault motion should break open these cavities and release a flux of helium gas that can be detected at surface,\u201d Professor McInnes said.<\/p>\n
\u201cOur team has previously demonstrated that minerals in diamond-bearing kimberlite pipes have uniquely low abundances of helium, and this technology can be used to rapidly scan exploration samples to both detect kimberlitic zircon and identify the age of the kimberlite pipe.\u201d<\/p>\n
Dr Bruce Godfrey, CEO of ASI Pty Ltd, said the company was pleased to collaborate with Curtin in the development of this innovative geochemical technique.<\/p>\n
\u201cWe look forward to developing the instrument platform for the international market,\u201d Dr Godfrey said.<\/p>\n