Geochronology dating techniques
“We then used the concentrations of three noble gas isotopes Ar produced by cosmic rays at the Martian surface to determine how long the sample had been exposed on the surface of Mars.” Analyses of data unveiled that the estimated age of the Cumberland rock was between 3.86 billion to 4.56 billion years, and that it had been exposed to the Martian surface for 60 million to 100 million years.
“Sixty to 100 million years of exposure for the sample is very recent for that site, suggesting that active geological processes have removed the shielding layers above the rock in the recent past,” Professor Vasconcelos said.
The team adapted specialised geochronological techniques used on Earth to determining the age and exposure history of rocks.
Professor Vasconcelos said the significance from a geological perspective was that the more recent the exposure, the more likely that an area could potentially be hosting signs of life.
For geological purposes, this is taken as one year.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
There are two basic approaches: relative age dating, and absolute age dating.
Luminescence dating is inherently experimental given the varying nature of these sediments and we have been working towards a better understanding of the luminescence properties of sediments on Calvert Island.
C) dating is one commonly used method, but it is limited by the availability of organic material (not always adequately preserved, or found in stratigraphic context), potential contamination, and an upper age limit of about 50,000 years.