Isotope Geochemistry

Caltech has had a long history in both stable and radiogenic isotope geochemistry including Clair Patterson's first accurate determination of the age of planet earth. Currently, we have active programs in the following areas.

Stable Isotopes

Since their discovery by Sir J. J. Thomson in 1913, stable isotopes have become powerful tracers of physical and chemical processes at all scales: capable of unraveling the details of galactic and solar system evolution, planetary differentiation, paleo-climates and oceans, human migrations or igneous processes. GPS is the host of a vibrant suite of stable isotope laboratories operated by professors Adkins, Eiler, Farley, Sessions, Tejada and Tissot, whose state-of-the-art clean laboratories and combined instrumentation allows for the investigation of virtually any isotope systematic (e.g., MC-ICPMS, TIMS, Orbitrap-MS, IRMS, noble-gas mass spectrometers, ion probes, spectroscopic isotope analyzer). In keeping with a long tradition of analytical developments (the first clean laboratory was built at GPS by Clair Patterson and the first digital mass spectrometer by Gerald Wasserburg) the stable isotope facilities at GPS continue to be the stage of the development of prototype instruments (e.g., ULTRA, Orbitrap), which are providing novel ways to study outstanding questions in Earth and Planetary Sciences.

Rare Gas Isotopes

Professor Farley has developed a method for using the helium-4 generated from the decay of uranium and thorium in apatite to study the thermal history of the host rock. From these studies, he is able to establish the rate of mountain range exhumation. He also uses the concentrations of helium-3 in seafloor sediments to determine the accretion rate of cosmic dust back through time. Striking variations in the accretion rate occur over time.