Cosmogenic isotope surface exposure dating

12-Sep-2019 05:50

This work was done in collaboration with Julie Libarkin at Ohio University.

Work continues with Doug Burbank at UCSB and Caltech graduate student Willy Amidon.

No longer should it be considered a major player in postglacial sea-level rise.However cosmogenic He dating of additional minerals which are known to retain He at Earth surface conditions, especially the common accessory phases apatite, sphene, and zircon.The challenge of working with these minerals is their small grain size, which causes a variety of nuclear effects associated with the long stopping range of He in the accessory phases separated from a tuff in Bolivia.This technique involves measuring the abundance of isotopes that are produced within rock surfaces when they are exposed to cosmic radiation.Ice cover blocks the penetration of cosmic radiation, halting production of such isotopes; their abundance in a rock therefore gives a measure of the time since ice retreated: the ‘exposure age’.

No longer should it be considered a major player in postglacial sea-level rise.

However cosmogenic He dating of additional minerals which are known to retain He at Earth surface conditions, especially the common accessory phases apatite, sphene, and zircon.

The challenge of working with these minerals is their small grain size, which causes a variety of nuclear effects associated with the long stopping range of He in the accessory phases separated from a tuff in Bolivia.

This technique involves measuring the abundance of isotopes that are produced within rock surfaces when they are exposed to cosmic radiation.

Ice cover blocks the penetration of cosmic radiation, halting production of such isotopes; their abundance in a rock therefore gives a measure of the time since ice retreated: the ‘exposure age’.

The most commonly used "cosmogenic isotopes" are radionuclides (He, require far less labor intensive purification and a simple sector-field mass spectrometer.