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Re: [dinosaur] Size of the Chicxulub crater

Yes, there have been some HUGE advancements in radiometric dating precision, and the recalibration of the argon scale against U-Pb and astronomically-controlled systems.

On Sun, Jun 18, 2017 at 6:51 PM, Dann Pigdon <dannj@alphalink.com.au> wrote:

On Fri, Jun 16th, 2017 at 9:51 PM, Thomas Richard Holtz <tholtz@umd.edu> wrote:

> Yes, the 180 km is probably the most accurate, and current dating for the
> boundary is 66 Ma. Those who still use 65.5 or 65 have not kept up with the
> new dating techniques and results.

The date given by Renne et all in 2013 seems to have a surprisingly small standard deviation;
66.043 +/- 0.011 MYA. That would seem to narrow it down to within a 44,000 year time span
(at two standard deviations). Is Argon-Argon dating really that precise?

I worked as an archaeologist for many years, and I was used to seeing much larger standard
deviations on much more recent dates (C14, thermoluminescence, Uranium-Thorium, etc).
Admittedly that was around the turn of the century, so technology may have (in fact, most
likely *has*) advanced somewhat since then. :-)


 Dann Pigdon
 GIS Officer
 Melbourne, Australia


Thomas R. Holtz, Jr.
Email: tholtz@umd.edu         Phone: 301-405-4084
Principal Lecturer, Vertebrate Paleontology

Office: Geology 4106, 8000 Regents Dr., College Park MD 20742

Dept. of Geology, University of Maryland

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