Wikipedia's definition of astrochronology is:

"Astrochronology is the dating of sedimentary units by calibration with astronomically tuned timescales, such as Milankovic cycles,1[2] or even sunspot cycles. When used in concert with radiometric dating, it allows the resolution of timescales to a high degree of accuracy. If orbital precession cycles are identified, the dating error can be as low as 21,000 years."

source: wikipedia


Is this method really used and does it have a good reputation among field geologists?

  • 1
    $\begingroup$ I don't have time to write a proper answer but yes it is definitely used, at least for the Cenozoic. In fact some stage boundaries and many magnetostratigraphic chrons are calibrated with it (see for instance the whole corpus of work by T. Westerhold, with an OA example here for the Ypresian) $\endgroup$
    – plannapus
    Oct 4 '18 at 11:50

Yes it is used and it works. I've heard varying viewpoints on it's accuracy and dependability though. I remember my earth science lecturers were in three camps with it:

  • one felt that the dates weren't consistently reliable, the data he'd gotten from astro-dating in the past had very poor independent confidence margins when there was no radiometric calibration. He implied that the results felt as though they had been pulled out of thin air.

  • two would gather testable material for future study but didn't use astro-dating themselves. It was an interesting but immature technique that might be useful in future but not to them.

  • only one felt that it was really, immediately useful.

Do note that this is in New Zealand, we're a geologically young and active country, so much so that we rarely need longer range radiometric testing like Uranium-Lead or even Potassium-Argon, we can Carbon date most of the sites we're interested in. Fine calibration of longer range datings is much less of an issue here than in older, more settled, locations.


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