consequences of dating at a young age - Apatite helium dating
Apatite is the defining mineral for 5 on the Mohs scale.
Hydroxyapatite, also known as hydroxylapatite, is the major component of tooth enamel and bone mineral.
although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. This tendency is reflected in the mineral's name, which is derived from the Greek word απατείν (apatein), which means to deceive or to be misleading.
By modelling ages through a variety of different thermal history scenarios, it is possible to define the range of histories giving predictions which are consistent with measured ages.
The thermal history framework provided by AFTA forms a solid basis for this procedure.
However, effects related to grain size may be significant in the interpretation of apatites from sediments which have been heated to paleotemperatures within the He PRZ, as grains of different radii will give different ages for a particular thermal history. The effects of long alpha-stopping distances on (U-Th)/He ages.
While this has yet to be demonstrated in natural samples, this holds considerable promise for obtaining more precise thermal history control in sedimentary basins. Ken Farley of Caltech, based on the systematics presented in Farley (2000) and references therein, allows modelling of the (U-Th)/He age expected from any inputted thermal history, in grains of any specified radius.
This key observation implies that for any specified thermal history, modelled (U-Th)/He ages can be produced for a particular sample using the measured mean grain size together with single values of the key diffusion parameters E/s.