Paleontologists still commonly use biostratigraphy to date fossils, often in combination with paleomagnetism and tephrochronology.
This function is able to tell researchers how old a sample is. But there's a wrinkle in the process that has been overlooked.
The ratios of strontium-86 to rubidium and strontium-87 are thought to only be influenced by the radioactive decay of the rubidium-87 into strontium-87.
"Paper spotlights key flaw in widely used radioisotope dating technique." Science Daily. To date, examining patient tissue samples has meant cutting them into thin slices for histological analysis.
This might now be set to change, thanks to a new staining method. Engineers have developed a new technique to test for a wide range of micropollutants in lakes, rivers and other potable water sources that vastly outperforms conventional methods.
Paleomagnetism: Earth’s magnetic polarity flip-flops about every 100,000 to 600,000 years.
The polarity is recorded by the orientation of magnetic crystals in specific kinds of rock, and researchers have established a timeline of normal and reversed periods of polarity.
And atoms of strontium-86 can diffuse more readily than atoms of strontium-87 or rubidium, simply because atoms of strontium-86 are smaller.
"It's a slow process, but not necessarily a negligible one when you're talking about geological time scales," says Robert Hayes, an associate professor of nuclear engineering at NC State and author of a paper describing the work.
So, researchers "normalize" the data by making a ratio with strontium-86, which is stable -- meaning it doesn't decay over time.