Old, old rock
This just in! The New York Times reports that a rock from Quebec may be the new title-holder in the "Oldest Rock On Earth" competition, unseating its fellow countryrock, the Acasta Gneiss of the Northwest Territories. In a study today in Science, Rick Carlson of the Carnegie Institution of Washington (a local boy!) and colleagues report a 4.28 Ga date for the rock (which appears to be a gneiss, though the article didn't say for sure, and I can't yet access the original paper). More after I read the original article by Carlson, et al. ...
Labels: canada, dc, geologic time, news
4 Comments:
Ooh, and it looks old, too...
Even though holding 4.56 billion year old meteorites is kinda neat, I have to say I'd like to get my hands on some really ancient terrestrial rock sometime...
This discovery is especially cool in that, unlike the Jack Hills zircons (Western Australia, formed at 4.4 Ga), this is actual rock, rather than individual crystals. We need them to find some zircons in the aforementioned rock, though, so we can do some proper absolute dating, rather than the 146Sm-142Nd isotopic dating they used in this paper (not that I doubt their methods, but absolute dating is always preferred).
(I posted on this too: http://www.goodschist.com/2008/09/26/oldest-rocks-ever-discovered-on-earth/)
Oh, lovely, does anyone have photos of thin-sections of it up on line? I'd love to get a closer look at it...
NPR story on this rock.
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