An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia

Details An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia

Jul 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999e%26psl.170..463h&link_type=abstract

Earth and Planetary Science Letters, Volume 170, Issue 4, p. 463-474.

Mathematics

Logic

25

Scientific paper

We have analyzed helium ages of apatites from several boreholes in the Otway basin, Australia, to evaluate whether laboratory helium diffusivity can be accurately extrapolated to conditions relevant in nature. Downhole apatite helium ages define a broad swath of values from 78-71 Ma at the surface (15°C) to nearly zero at depths corresponding to ambient temperatures of ~80°C. The width of the swath results from uncertainties in corrected borehole temperatures, differences in the thermal history experienced by the various boreholes, and possibly from slightly different helium diffusivities among the detrital apatite grains studied. In the eastern Otway basin, the shape and position of the helium age profile is in good agreement with predictions based on the extrapolation of laboratory diffusivity data for Durango apatite coupled with published thermal histories for this part of the basin. In contrast, helium ages are much younger than predicted in the western Otway basin. Based on measured ages from Otway sediments, which have been essentially isothermal over the last few million years, an empirical diffusivity (D/a2) of 2×10-15 s-1 can be assigned to apatites residing at downhole temperatures of 67-97°C. This empirical diffusivity is consistent with laboratory diffusion measurements, demonstrating that such measurements are reasonably accurate and can be applied with confidence to natural geologic settings. Given this confirmation of the laboratory diffusivity data, the discrepancy between the observed and modeled helium age profiles in the western Otway basin suggests that these sediments recently experienced higher temperatures than presently supposed.

Affiliated with

Also associated with

No associations

Rating

An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An empirical test of helium diffusion in apatite: borehole data from the Otway basin, Australia will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1620465