1. Annealing of fission tracks in wide-range,
radiation-damaged detrital zircon
Garver, J.I. Department of Geology, Union College
Zircon undergoes a crystalline-to-amorphous transition by radiation damage, which causes internal disorder and lowers retention and stability of fission tracks.
Optical images of thin sections of highly damage Cambrian detrital zircon, NY State
[1] ZFT Ages of detrital zircon from Cambrian strata (NY) range from ~300 Ma to over 2000 Ma. Samples with greater thermal maturity (east) also a young ZFT population at 460 Ma and ~270 Ma, which coincides thermal events of the Taconic and the Alleghanian orogeny.
[2] Annealing of Radiation Damaged grains in heated basin strata. The time of last heating to c. 200°C can be well dated using ZFT reset ages from detrital zircon as demonstrated in the Hellenic forearc (Greece), and the Chugach Accretionary complex and flanking basins (Alaska).
[3] Measurement of radiation damage by Raman Spectroscopy.
Grain-to-grain variation in radiation damage can be used to explain over-dispersion of ZFT grain ages in reheated samples.
Fission-track dating radiation-damaged zircon grains can be used to date the time rocks are heated to the upper bounds of the oil/gas window
Raman Laser scattering on zircon mount