[meteorite-list] exact Carolina Bay crater locations, RB Firestone, A West, et al, two YD reviews, 2008 June, 2009 Nov, also 3 upcoming abstracts: Rich Murray 2009.11.14

From: Ted Bunch <tbear1_at_meteoritecentral.com>
Date: Sun, 15 Nov 2009 10:09:15 -0700
Message-ID: <C72583CB.F1ED%tbear1_at_cableone.net>

Patience Darren. Listed below are the various scenarios presently considered
to account for the YD "impact"event. When there is an absence of a crater,
research needs to dig deeper, much like the position of the Alvarez group in
the '80s before a crater was found for the K/T event. We know that airbursts
have happened in the past (e. g., Tunguska), the questions are, how big have
they been and how big can they be?

What was presented prior to 2006 has little to do with present
considerations concerning the origin of the YD event based on the efforts of
>60 scientists from eight countries. Most of these efforts have focused on
analyzing materials from sites that occur from California to the Caspian
Sea, not speculating on potential origins. However, we do need to work the
data with various impact options in order to see what are good and bad fits:


(1) An extraordinary accretion of micrometeorites (Pinter and Ishman, 2008),
which is inconsistent with YDB carbon spherule compositions and the huge
amount of nanodiamonds found within the YDB carbon spherules.
(2) Oblique impact (s) into the Laurentide Ice Sheet. This model does
account for the absence of a crater and the lack of cratering markers.
Also provides for the shock production of the many cubic and lonsdaleite
(hexagonal) nanodiamonds found in the YDB.
(3) Impact-induced aerial burst (s), e. g, Boslough and Crawford (2007);
Shuvalov (2008). The lack of high shock pressures in an aerial detonation
does not necessary preclude the formation of cubic and hexagonal diamonds.
Maruyama et al., (1993) made hexagonal and cubic diamonds by a CVD process
from a high temperature plasma atmosphere (13,000 ?C) under conditions
similar to those in an aerial burst. The Tunguska event is commonly accepted
as the result of a near surface aerial burst and has many similarities with
the YD event, including diamonds.
(4) Comet grazing of the atmosphere (Drobysheski, 2009). Nearly tangent
entry of a comet into the Earth?s atmosphere with partial detonation and
melting followed by escape of the unexploded nucleus into space. Has the net
effect of an atmosphere-penetrating aerial burst followed by global fallout
of detonation products.

More work and time may give us a better understanding of the YD impact
mechanism. In the meantime, I suggest that you are what needs to be peeled
off the wall. Get a clearer focus on pertinent literature and on-going
research - the upcoming AGU Meeting, with pro and con abstracts on the
subject, is a good place to start.

Ted Bunch




On 11/15/09 8:47 AM, "Darren Garrison" <cynapse at charter.net> wrote:

> On Sat, 14 Nov 2009 23:39:04 -0700, you wrote:
>
>> It is consistent with the ejecta layer from an impact event and
>
> ...
>
>> ejecta layer is consistent with an impact near the Great Lakes
>> that deposited terrestrial-like ejecta near the impact site and
>> unusual, titanium-rich projectile-like ejecta further away.
>
> ...
>
>> Ni, Co, U, Th and other trace element abundances are inconsistent
>> with all terrestrial and extraterrestrial (ET) sources except for
>> KREEP, a lunar igneous rock rich in potassium (K), rare-earth
>> elements (REE), phosphorus (P), and other incompatible elements
>> including U and Th.
>
> ...
>
>> Four holes in the Great Lakes, some deeper than Death Valley,
>> are proposed as possible craters produced by the airburst
>> breakup of a loosely aggregated projectile.
>
> ...
>
>> the Great Lakes or Hudson Bay. The magnetic grains and
>> spherules have an unusual Fe/Ti composition similar to lunar
>> Procellarum KREEP Terrane and the organic constituents are
>> enriched in 14C leading to radiocarbon dates often well into
>> the future.
>> These characteristics are inconsistent with known meteorites
>> and suggest that the impact was by a previous unobserved,
>> possibly extrasolar body.
>
>
>
> Okay, a review-- so far this impactor has been a 500 mile wide snowflake from
> the atmosphere of a supernova hitting at hundreds of kilometers per second.
> It
> has been an airburst over ice leaving no crater. It has left craters deeper
> than Death Valley in the Great Lakes. It has caused golden showers and a rain
> of diamonds that lasted for months. It shotgun-blasted iron particles into
> the
> tusks of mammoths. It has been a comet. It has been a chondrite, and all
> meteorites found by or through Nininger have been debris from it, so it was
> actually all types of chondrite and everything else Nininger collected. Now,
> it
> is an extrasolar lunar meteorite from the future.
>
> So, to sum it up, this 500 mile 10 mile very low-density metal and stone
> filled
> comet-asteroid supernova-produced lunar snowflake that struck at hundreds of
> kilometers per second did and didn't produce impact craters and left no marks
> except for the Great Lakes and thousands of very shallow overlapping, highly
> oblong pits exactly like craters from an impact event except for craters from
> an
> impact event rarely being very shallow, overlapping, highly oblong pits. It
> killed off all the lost Ice Age fauna at once, except for all of the Ice Age
> fauna, which went extinct at different times in different locations and spread
> out over thousands to tens of thousands of years (in some spots pretty darn
> well
> timed with the establishment of human populations, coincidence or no.) Oh,
> and
> somehow a supernova is still involved.
>
> That isn't refining an idea-- that is throwing everything you can think of
> against the wall and hoping that some of it sticks.
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Received on Sun 15 Nov 2009 12:09:15 PM PST