We should check the raw data in an apatite fission track analysis report against the known geologic history of an area (and its expected thermal history) to verify or refine a vendor's interpretation. Overall, mean track length should decrease as depth and/or temperature increase. A service company's report cites the fission track length as a mean of the total population of fission track lengths measured. Instead, many readings need to be made to achieve a high confidence level. One reading of fission track length is not enough to make a valid determination of the thermal history of a sample.

Also, one should make sure caved material has not contaminated a sample of drilling cuttings. One should consider this effect when interpreting apatite data. The chemistry of apatite is variable and can be significant enough to have an effect on the rate of fission track annealing. See Duddy et al and Gleadow et al for a general overview of the interpretation and application of apatite fission track data in petroleum exploration.

The amount of information provided from fission track analysis can be significant and is very complementary to vitrinite data in portions of the geologic section that are lean in organic matter. Therefore, the length of apatite fission tracks can be used as a measure of the maximum temperature that a rock has been subjected to and provides information related to thermal history.ДЄpatite grains are commonly found in sandstones. Fission tracks will completely anneal and disappear at approximately 120вЊ 393.15В KД§07.67В В°R. The mean length of a fission track at the time of formation and up to 60вЊ 333.15В KДҐ99.67В В°R is 15Ој. This process is referred to as annealing. However, as the temperature increases from 60- 120вЊ 393.15В KД§07.67В В°R, the length of the fission tracks in apatite crystals will decrease due to thermally induced вЂњhealingвЂќ of the crystal structure. At temperatures below 60вЊ 333.15В KДҐ99.67В В°R the fission tracks exist as they were formed. The continued existence of apatite fission tracks is temperature dependent. Measuring maturity with apatite fission tracks This is the basis for apatite fission track analysis. The rate of decay of uranium 238 is a time-dependent reaction therefore, the number of fission tracks in a crystal can be used to measure the time since the formation of the apatite grains. The damage appears as linear features referred to as fission tracks. The highly charged particles released by the fission reaction damage the lattice of apatite crystals.

7 Example of fission track length interpretationДЄpatite fission tracks are formed when charged particles are released by the spontaneous nuclear fission of uranium 238 in apatite crystals.

2 Measuring maturity with apatite fission tracks.

1 What is apatite fission track analysis?.

Fission uranium wikipedia