Uranium dating zircon
Zircon is a common accessory to trace mineral constituent of most granite and felsic igneous rocks.Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands.Instead, it suggests water was present in the liquid magma ocean that formed the zircon crystals."We'll never know how much water there really was, but the simplest interpretation of those zircons coming from granitic rocks, is that we had a hydrous planet right from the very beginning," says Bowring.Colourless specimens that show gem quality are a popular substitute for diamond and are also known as "Matura diamond".The name derives from the Persian zargun, meaning "gold-hued". It occurs as a common accessory mineral in igneous rocks (as primary crystallization products), in metamorphic rocks and as detrital grains in sedimentary rocks.Uranium radioactively decays into lead at a known rate, allowing age to be determined based on the ratio of uranium to lead in the sample.
halfway between granite and basalt." Valley and colleagues have previously used uranium-lead radioactive dating to determine the age of a zircon crystal sample (named 01JH36-69), which was found 15 years ago in metamorphosed sandstone at Jack Hills, 800 kilometres north of Perth.
"We're getting the true ratio of the parent uranium to daughter lead, and therefore we're getting the true age." The age confirmation closes the gap between the Moon-generating impact, and the formation of Earth's crust, according to Professor Samuel Bowring of the Massachusetts Institute of Technology.
Bowring, who wrote an accompanying opinion piece on the research, believes the findings indicate Earth's water didn't need to come from asteroids, during a period known as the late heavy bombardment 3.9 billion years ago.
Zircon forms in silicate melts with large proportions of high field strength incompatible elements.
For example, hafnium is almost always present in quantities ranging from 1 to 4%.