Helium diffusion dating carbon dating oops
Remarkably, thermal modelling of FHe yields comparable results to the well-established modelling based on AFT and AHe.Experiments co-sponsored by the Creation Research Society show that helium leakage deflates radioisotopic ages.This prompted Robert Gentry at Oak Ridge National Laboratory to ask the Los Alamos team to send him core samples from various depths in GT-2 (as well as samples from deeper boreholes nearby).Gentry and his team extracted zircons from the samples, hand-picked crystals between 50 and 75 microns long (Figure 3), and measured the total amounts of helium in them.When creationists became aware of Gentry’s data, many of us thought that it would have been impossible for the zircons to have retained that much helium for even a million years, much less over a billion years.Helium is a lightweight, fast-moving atom that does not attach itself to other atoms, so it diffuses (spreads out) through the atomic lattices of most minerals relatively fast.The site was Fenton Hill, on the west flank of the Valles volcanic caldera in the pine-covered Jemez Mountains.Two dozen miles to the east, geoscientists at Los Alamos National Laboratory analyzed the drill cores, investigating whether the hot, dry rock would be suitable for providing geothermal energy.
They found that “an almost phenomenal amount of He has been retained” in the zircons, despite them being small, hot, and allegedly old (Gentry et al., 1982a).
In the context of these zircons, “excess” helium would correspond to retentions greater than 100% of the amount nuclear decay could produce in 1.5 Gyr. As we explain in “Latest results arrive in mid-2003” on page 8 of this paper, the uniformitarian method of “helium dating,” called (U-Th)/He chronometry, is entirely different from the helium diffusion dating we are employing here.
Uniformitarian “helium dating” methods would not call attention to the large helium retentions we are concerned with, so it may be that sites like borehole GT-2 are common throughout the world.
Precise analysis of the diffusion characteristics of helium in fluorite is crucial for establishing the new fluorite (U–Th–Sm)/He thermochronometer (FHe), which potentially provides a powerful tool for dating ore deposits unsuitable for the application of conventional geochronometers.
Incremental helium outgassing experiments performed on fluorites derived from a spectrum of geological environments suggest a thermally activated volume diffusion mechanism.