Arizona radiogenic helium dating laboratory puma knives dating

11 Mar

The (U-Th)/He chronometer has become well known in the past twenty years, but it is not the only chronometer based on production of alpha particles by uranium and thorium.

While the vast majority of the energetic alpha particles emitted during uranium and thorium decay come to rest as stable helium-4, a small minority react with other isotopes to form new nucleogenic daughter products.

Just to show you what I've been up to lately, here is a shot of some of my favorite secondary minerals from my favorite place in the world.

During the last two years, I have worked with the JPL Planetary Surface Instruments group on a quadrupole ion trap mass spectrometer.

This instrument has been developed for years at JPL by Stojan Madzunkov, Murray Darrach, and others.

Relative ITCZ position is strongly influenced by hemispheric temperature contrasts and subsequent atmospheric restructuring, which draw the ITCZ towards the warmer hemisphere, a trend possibly driven by asymmetrical hemispheric warming due to the relative cooling effect of anthropogenic sulphate aerosols in the Northern Hemisphere, but that could also arise from undetected natural variability.

Climate models have attempted to assess the relative contributions of greenhouse gases (GHGs) and aerosols to ITCZ displacement with contradictory results.