Space/Science — HabitableZone

Space/Science » in reply to re: Getting impact chronology straight

re: Getting impact chronology straight
Nick Hoffman — (archived)

Ok. What I mean is when the Hellas impact occured parts of it may have gotten to Earth and brought contamination at the time. While this is too early for the dinosaurs ( I misspoke like Cheney) we don't know what level of life there was on Earth at the time. Also the figure of 3.6 billion years is just a vague estimate. I doubt many in the field would consider it outragous to say the impact might have happened 1 or 2 billion years ago

OK, stop right there.

Every single worker in the Mars field would find it totally outrageous to claim that Hellas might have occurred as young as 1 or 2 Billion years ago. To claim otherwise shows that you are totally unfamiliar with the literature an Mars and the Moon and are speaking in vapours.

The only arguments there have been recently about age dating on Mars are:-

1) Whether the Amazonian began as young as 700 Ma, or as old as 3 Ga. (The Amazonian is the youngest period on Mars, when very few impacts occurred) The proponents were Hartmann and Neukum, and both took as a given that the Noachian (which POST-dates Hellas) began somewhere between 4.0 and 3.7 Ga.

2) A question of whether there was a flurry of impact events on the Moon at 3.9 Ga, rather than a steady progression from accretion to impacts to steady-state. This debate is not yet resolved, AFAIK, but is irrelevant to Hellas. In either model, Hellas predates 3.9 Ga.

We know categorically for the Moon that Hellas-scale basin-forming events predate the lunar mare basalts, radiometrically dated at 2.8 Ga and older.

There is no way on God's Earth that you are right. Go read some Mars books then come back when you know what you are talking about.

(rant mode off)

Seriously, Greg, learn a bit more before commiting electrons to your service on this...

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