The Earth\u2019s deepest diamonds are commonly made up of former living organisms that have effectively been recycled more than 400 kilometres below the surface, new Curtin research has discovered.<\/p>\n
The research, published in Nature\u2019s Scientific Reports<\/em>, found that both diamonds found in oceanic rocks and the so-called super-deep continental diamonds shared a common origin of recycled organic carbon deep within the Earth\u2019s mantle.<\/p>\n Lead author Dr Luc Doucet, from Curtin\u2019s Earth Dynamics Research Group within the School of Earth and Planetary Sciences, said the findings offered a fascinating insight into the world\u2019s most expensive gemstones.<\/p>\n \u201cBringing new meaning to the old trash to treasure adage, this research discovered that the Earth\u2019s engine actually turns organic carbon into diamonds many hundreds of kilometres below the surface,\u201d Dr Doucet said.<\/p>\n \u201cBallooning rocks from the Earth\u2019s deeper mantle, called mantle plumes, then carry the diamonds back up to the Earth\u2019s surface via volcanic eruptions for humans to enjoy as sought-after gemstones.<\/p>\n \u201cWhile recycling is becoming a modern-day necessity for our sustainable survival, we were particularly surprised to learn, through this research, that Mother Nature has been showing us how to recycle with style for billions of years.\u201d<\/p>\n The three main types of natural diamonds include oceanic, super-deep continental and lithospheric diamonds, formed at different levels of the mantle with a varying mixture of organic and inorganic carbon.<\/p>\n Co-lead author John Curtin Distinguished Professor Zheng-Xiang Li, the Head of the Earth Dynamics Research Group, said the research provided a model that explains the formation and locations of all three major types of diamonds.<\/p>\n \u201cThis is the first time that all three major types of diamonds have been linked to mantle plumes, ballooning hot rocks driven by plate tectonics and the supercontinent cycle from deeper Earth,\u201d Professor Li said.<\/p>\n \u201cThis research not only helps to understand Earth\u2019s carbon cycle, but also has the potential to unlock more secrets of the Earth\u2019s dynamic history through tracking the past locations of mantle plumes and superplumes. This can be achieved by mapping out the distribution of both continental and oceanic diamonds.\u201d<\/p>\n However, Professor Li said it remained a mystery as to why diamonds formed in the so-called \u201cmantle transition zone\u201d, 400 to 600 kilometres deep, utilised recycled organic carbon only.<\/p>\n \u201cThis might have something to do with the physical-chemical environment there\u201d, Professor Li said. \u201cIt is not uncommon for a new scientific discovery to raise more questions that require further investigation.”<\/p>\n