Fission track dating solid earth sciences library
The method involves using the number of fission events produced from the spontaneous decay of uranium-238 in common accessory minerals to date the time of rock cooling below closure temperature.
Fission tracks are sensitive to heat, and therefore the technique is useful at unraveling the thermal evolution of rocks and minerals.
Additionally low-uranium epidotes and garnets may be used for very old samples (Paleozoic to Precambrian).
The fission-track dating technique is widely used in understanding the thermal evolution of the upper crust, especially in mountain belts.
Da das Verhältnis von U des untersuchten Minerals berechnet werden.
The external detector is typically a low-uranium mica flake, but plastics such as CR-39 have also been used.
The resulting induced fission of the uranium-235 in the sample creates induced tracks in the overlying external detector, which are later revealed by chemical etching.
The process of track production is essentially the same by which swift heavy ions produce ion tracks.
Chemical etching of polished internal surfaces of these minerals reveals spontaneous fission tracks, and the track density can be determined.