[meteorite-list] (no subject)

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Thu, 26 Jan 2017 15:09:13 -0500
Message-ID: <159dc657219-4504-8cf0_at_webprd-a95.mail.aol.com>

Thanks Doug,
Got to really dig into this paper to make sense of the conclusion which is only speculative and needs
to be further evaluated for positive confirmation bias and field and lab work around the world. It was
quite top heavy on analysis which appears well done!

The authors, or maybe it was the press, used the study's 270 kg dissolved sample of well-characterized
"chronostratigraphic" sediments from a Russian deposit in the study which got approved for publication
in the prestigious journal, "Nature", if I read it correctly.

It would have been more rigorous for my taste if it had been reviewed by MAPS editors, or the like, where the focus
 would have been more on interpretation, than on methodology. Just my opinion, as both are important.
It is an interesting subject - do we call it paleo-meteoritics? Getting any paper into Nature deserves congrats
for sure but I expected to be more awed from their editorial staff choices. Luckily no one told that to the Alvarez'.

In the end the conclusion is that ordinary chondrites used to be a significantly lower proportion of finds, nearly a
half billion years ago according to the results of their study. Then 466 mya that all changed with the disruption
of an L parent body. I didn't notice special mention of H- or L-chondrites, so the assumption IMO is that that another
event happened recently. None of this seems remarkably insightful but perhaps the authors point of view is
that here's a smattering of evidence that confirms the idea that the ratios of meteorite classes will vary throughout
geological ages which is nice when things make sense and people begin to dimension it with the 'fossil' record.

Kindest wishes
Doug

-----Original Message-----
From: Doug Ross <doug at dougross.net>
To: mexicodoug <mexicodoug at aol.com>
Cc: Meteorite List <meteorite-list at meteoritecentral.com>
Sent: Wed, Jan 25, 2017 1:38 pm
Subject: Re: [meteorite-list] (no subject)

Hi Doug,

Here is a link to the original paper:

http://www.nature.com/articles/s41550-016-0035

"Our data show that the meteorite flux has varied over geological time as asteroid disruptions create new fragment populations that then slowly fade away from collisional and dynamical evolution. The current flux favours disruption events that are larger, younger and/or highly efficient at delivering material to Earth."

Cheers from the ?other? Doug,

Doug Ross
Received on Thu 26 Jan 2017 03:09:13 PM PST