[meteorite-list] Carancas crater

From: Ted Bunch <tbear1_at_meteoritecentral.com>
Date: Thu, 28 Feb 2008 12:07:47 -0700
Message-ID: <C3EC5493.52AD%tbear1_at_cableone.net>

I am not sure why there is an argument about whether or not Carancas is an
impact crater. Of course it is! In scientific terminology, impact pit is not
acceptable. Let's review the facts:

1) The Carancas crater was produced by a hypervelocity impactor that
excavated a deep hole and formed a raised rim of target materials
(unconsolidated clastic debris).
2) Produced ejecta rays out 350 m from the crater
3) The event had sufficient shock energy to cause classic shock features in
target quartz.
4) There is no size limitation for use of the term "crater" as long as the
feature fits the accepted scientific constraints, e. g., formed by
hypervelocity impact. LDEF (Long Duration Exposure Facility) flew in space
for 5.5 years and studies of the facility skin showed thousands of craters
as small as a few microns. Similar tiny craters have been found all over
space shuttle vehicles. Apollo glassy spherules and rock samples show tiny
impact craters as do several meteorite surfaces. In all of these cases,
scientific reports used the term "crater".

Ted Bunch

(an innocent bystander with 40 + years of professional experience in impact
cratering)








On 2/28/08 11:01 AM, "mmorgan at mhmeteorites.com" <mmorgan at mhmeteorites.com>
wrote:

> All:
> See the site (http://unb.ca/passc/ImpactDatabase).
> On the first page you will find the criteria for inclusion within this
> database (which is the most comprehensive and well-researched list on the
> planet). Sikhote-Alin is listed, Carancas is not (yet?). Also note Wabar and
> Haviland, both of which are termed "craters" and do fall within Adam's range
> of 5-20 m.
>
> The term impact "pit" is not listed in the Glossary of Geology (Jackson, 1997,
> 4th ed.), and is thus likely a loosely-used definition. Impact crater is
> listed in the Glossary and is defined as "a generally circular crater formed
> either by impact of a projectile on a planetary surface or by an experimental
> hypervelocity impact of a projectile into solid matter..."
>
> I would hedge a bet that Carancas will be considered an impact crater.
>
> Matt
> ----------------------
> Matt Morgan
> Mile High Meteorites
> http://www.mhmeteorites.com
> P.O. Box 151293
> Lakewood, CO 80215 USA
>
> -----Original Message-----
> From: Michael Farmer <meteoriteguy at yahoo.com>
>
> Date: Thu, 28 Feb 2008 09:40:39
> To:Adam Hupe <raremeteorites at yahoo.com>,Adam
> <meteorite-list at meteoritecentral.com>
> Subject: Re: [meteorite-list] Carancas crater
>
>
> I did not realize that the website you listed was the
> definitive and final place which determines craters vs
> pits. It seems that some of the top scientists in the
> world think that it is a crater, perhaps you should
> enlighten them.
> Carancas is a crater, and I am not sure:), but I do
> believe that the impact of a meteorite created it,
> thus, I am still confused, but would that not tend to
> suggest that it is meteoritic? Adam, I think
> regardless of whether it is a common chondrite, the
> simple fact that it exists forces science to
> re-calculate its models for impact craters by
> chondrites. So Carancas is extremely important. I
> forsee papers written about Carancas for decades.
> There will be no roof built, the crater is already
> mostly destroyed (as I predicted that it would be,
> thanks to those of us who went there, at least some
> material was preserved).
> Michael Farmer
>
> --- Adam Hupe <raremeteorites at yahoo.com> wrote:
>
>> Hi Mike and List Members,
>>
>> To me, Carancas produced an "impact pit" which is a
>> form of crater. I will concede the point that it is
>> also a crater by other definitions, just not
>> meteoritic. The Sikhote Alin event also produced
>> several impact pits that were described as such
>> further constraining the meteoritic definition of an
>> impact crater.
>>
>> Here is a great reference site that clearly defines
>> crater sizes of 5-20 meters as "impact pits".
>> Carancas only produced a 13 meter mud hole squarely
>> defining it as a pit.
>>
>> http://www.somerikko.net/old/geo/imp/listinfo.htm
>>
>> Pretty soon, the Carancas impact pit it will be no
>> more than a depression in the ground with urine,
>> fecal
>> matter and trash in it. Not to forget, a $90,000.00
>> roof will be added on top of a rotted out and the
>> most
>> common type of ordinary chondrite in existence at
>> the
>> bottom.
>>
>> All the best,
>>
>> Adam
>>
>>
>
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Received on Thu 28 Feb 2008 02:07:47 PM PST