Apatite helium dating
Assessment of (U-Th)/He thermochronometry: the low temperature history of the San Jacinto mountains, California. Yellow stones – purplish-pink, which is stronger in long wave; blue stones – blue to light-blue in both long and short wave; green stones – greenish-yellow, which is stronger in long wave; violet stones – greenish-yellow in long wave, light-purple in short wave.
House et al., 1997; Warnock et al., 1997; Wolf et al., 1997) have illustrated the potential of the technique to provide useful thermochronometric information at temperatures less than 100C. Chemical Geology (Isotope Geoscience Section), 112, 179-191.
A relatively rare form of apatite in which most of the OH groups are absent and containing many carbonate and acid phosphate substitutions is a large component of bone material.
Fluorapatite (or fluoroapatite) is more resistant to acid attack than is hydroxyapatite; in the mid-20th century, it was discovered that communities whose water supply naturally contained fluorine had lower rates of dental caries.
By incorporating both AFTA and (U-Th)/He ages into the modelling, a more restricted range of thermal history solutions can be extracted. Helium diffusion from apatite: general behaviour as illustrated by Durango fluorapatite.
Several studies suggest that the composition of the apatite does not appear to affect the sensitivity of the He closure temperature (Wolf et al., 1996; House et al., 1999), in contrast to the effect of Cl contents on AFTA annealing kinetics. Journal of Geophysical Research, 105 (B2), 2903-2914.