Guodong Li

Forty apatite samples of sandstone from ten exploration wells in the Scotian Basin, Offshore Canada, are used for fission track analysis and thermal history reconstruction. The sample depths range from 1000 to 5500 m. Fission tracks in all apatite samples are annealed. Apatite fission track ages for samples from Logan Canyon Formation are generally older than their deposition ages. These data indicate a high degree of track retention and therefore reflected the time of cooling in the source area. Samples from deeper formations (Missauga, Mic Mac and Verrill Canyon) give apatite fission track ages younger than their formation ages or zero ages, either indicating partial to total annealing of fission tracks in apatite.

Computer forward modelling of well constrained data indicates heating to palaeotemperatures of 80-110^oC

prior to cooling at some time during the interval 100-50 Ma in the Scotian Basin. This thermal overprinting in apatite samples is common throughout the study are and coincides with the peak time at which oil generation began in some wells. Zircon fission track data from fifteen samples in four wells suggest that these samples had never experienced temperatures higher than 235 ± 25·C since deposition.

The causes of this thermal anomaly is very likely to be the high heat flow related to rapid deposition during 150-90 Ma and fluid migration asociated with the process of oil generation in the Scotian Basin, during which releasing of overpressured hot fluid is likely to have occurred.

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Supervisor: Marcos Zentilli