Geochronology/Uranium-lead dating

Zircons contain trace amounts of uranium and thorium (from 10 ppm up to 1 wt%) and can be dated using several modern analytical techniques. Because zircons can survive geologic processes like erosion, transport, even high-grade metamorphism, they contain a rich and varied record of geological processes. Zircons are usually dated by uranium-lead (U-Pb), fission track, cathodoluminescence, and U+Th/He techniques.

Imaging the cathodoluminescence emission from fast electrons can be used as a pre-screening tool for high-resolution secondary-ion-mass spectrometry (SIMS) to image the zonation pattern and identify regions of interest for isotope analysis. This is done using an integrated cathodoluminescence and scanning electron microscope.

Detrital zircon geochronology, i.e., zircons in sedimentary rock can identify the sediment source.

Zircons from Jack Hills in the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, have yielded U-Pb ages up to 4.404 billion years, interpreted to be the age of crystallization, making them the oldest minerals so far dated on Earth.

The oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth. This interpretation is supported by additional trace element data, but is also the subject of debate. In 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in the Jack Hills of Western Australia. According to one of the researchers, "If life arose relatively quickly on Earth ... then it could be common in the universe."