Cratons contain the oldest rocks on the planet and hold much of the Earth's mineral wealth, including diamonds.Cratonic roots extend into the mantle more than 125 miles (200 km) deep where pressure is high enough, but temperature cold enough, for diamond formation.Diamonds come in two major varieties: eclogitic and peridotitic.
The findings are published in the September issue of Contributions to Mineralogy and Petrology. Many diamonds encase tiny mineral grains—what jewelers call impurities but geoscientists call inclusions—that can tell us how old the diamond is and what geologic processes occurred in the deep Earth billions of years ago.” Diamonds, dense forms of carbon, are the hardest natural substance known.
“Diamonds aren’t just for spectacular jewelry,” commented Shirey. The largest diamonds come from cratons—ancient continental regions and their deep roots that provided a nucleus around which younger continental material gathered.
Rhenium and osmium are natural radioactive isotopes.
These isotopes decay at a predictable rate and make good atomic clocks for determining absolute ages.
Subduction occurs when one crustal plate sinks and slides under another and is plunged hundreds of miles into Earth’s mantle.
This conclusion documents one of the oldest known examples of modern plate tectonics.One of the more recent developments is the carbon dating of bones and other carbon-containing materials that are supposedly millions of years old.Carbon dating uses the radioactive decay of carbon-14 into nitrogen-14, which currently has a half-life of 5,730 years.However, creation scientists have carbon-dated fossils, diamonds, and coal that are all supposed to be millions of years old.Nevertheless, they all have detectable amounts of carbon-14 in them. C.—For the first time, scientists have dated diamonds from the recently discovered diamond fields in Canada’s Northwest Territories and have found them to be the oldest precisely dated diamonds on Earth.