Australian diamonds may be nearly as Old as the (Jack) Hills

by William Atkins

Friday, 04 July 2008

Page 2 of 3 The leader of the research team, Alexander Nemchin, states, “The most common way to form light carbon on the modern Earth is photosynthesis.” [BBC News: “Diamonds hint at 'earliest life'”]   The researcher team states that the diamonds were formed only a few hundred million years after the Earth was itself formed. They explained in the abstract to their paper, “Detrital zircons more than 4 billion years old from the Jack Hills metasedimentary belt, Yilgarn craton, Western Australia, are the oldest identified fragments of the Earth's crust and are unique in preserving information on the earliest evolution of the Earth. Inclusions of quartz, K-feldspar and monazite in the zircons, in combination with an enrichment of light rare-earth elements and an estimated low zircon crystallization temperature, have previously been used as evidence for early recycling of continental crust, leading to the production of granitic melts in the Hadean era.” Nemchin, stated, "We believe this find to be the oldest terrestrial light carbon reservoir discovered so far.” [UPI: “Aussie diamonds give clues to early life ”] They also stated in their abstract, “Here we present the discovery of microdiamond inclusions in Jack Hills zircons with an age range from 3,058 +/- 7 to 4,252 +/- 7 million years. These include the oldest known diamonds found in terrestrial rocks, and introduce a new dimension to the debate on the origin of these zircons and the evolution of the early Earth.” Within the paper, the authors explain that their results do not prove when life first appeared on Earth, only suggests its time of beginning. However, they said that their results does “not exclude” that possibility. They stated, “The spread of ages indicates that either conditions required for diamond formation were repeated several times during early Earth history or that there was significant recycling of ancient diamond. Mineralogical features of the Jack Hills diamonds—such as their occurrence in zircon, their association with graphite and their Raman spectroscopic characteristics—resemble those of diamonds formed during ultrahigh-pressure metamorphism and, unless conditions on the early Earth were unique, imply a relatively thick continental lithosphere and crust–mantle interaction at least 4,250 million years ago.” Nemchin concludes, "The discovery challenges our fundamental understanding of processes active in the early history of the Earth. It suggests that life may well have appeared on Earth long before the period of heavy-meteorite bombardment believed by some to have initiated the emergence of life on Earth." [UPI] More research is needed. Please read on to find out why. << First page <   1 2 3 Next page > Last page - Post your comment >>

 

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