strontiumisotope

Strontium isotopes are variations of the element strontium that differ in their number of neutrons. The most geochemically significant isotopes are stable strontium-86 (⁸⁶Sr) and radiogenic strontium-87 (⁸⁷Sr), which is produced by the radioactive decay of rubidium-87 (⁸⁷Rb). Strontium-88 (⁸⁸Sr) is the most abundant stable isotope, making up about 82.6% of natural strontium. Strontium-84 (⁸⁴Sr) is the least abundant stable isotope.

The ratio of ⁸⁷Sr to ⁸⁶Sr (⁸⁷Sr/⁸⁶Sr) in a sample is a key indicator used in various scientific fields. This ratio varies depending on the geological origin of the strontium. Rocks with a high rubidium-to-strontium ratio that have been around for a long time will have a higher ⁸⁷Sr/⁸⁷Sr ratio due to the accumulation of ⁸⁷Sr from ⁸⁷Rb decay. Conversely, younger rocks or those with a low Rb/Sr ratio will have a lower ⁸⁷Sr/⁸⁷Sr ratio.

This isotopic signature is widely employed in geochemistry to trace the provenance of rocks, minerals, and fluids. It is also used in paleoclimate studies, archaeology to determine the origin of artifacts and human migration patterns, and even in forensic science. The predictable decay of ⁸⁷Rb to ⁸⁷Sr allows for the dating of rocks and minerals, providing insights into Earth's history. Analyzing strontium isotope ratios helps scientists understand geological processes, understand past environments, and answer questions about the origin and movement of materials.