[meteorite-list] Volcano Bomb & Impact Breccia Replys

From: Mark Fox <unclefireballmtf_at_meteoritecentral.com>
Date: Thu Apr 22 10:10:01 2004
Message-ID: <20030402142132.13193.qmail_at_web14902.mail.yahoo.com>

April 2, 2003

Greetings Meteorite Enthusiasts!

Sorry for the late post. I try to make a point to
read and reply to e-mails between 8:30-9:15 AM each
morning, and only then. It happened that I ran out
of time yesterday.

In any event, thank you everyone for all of your
expert help in regards to volcano bombs and
identifying impact breccias! It was much appreciated!
  

In regards to some comments and questions:

Mark Ferguson wrote:

"Hello Mark and List
Bombs are typically highly vessiculated magmas. What
you may be thinking of are ejected "old" magmas
which are ripped from the walls of a volcanic vent
and would have shapes that are irregular if not just
plain blocky. These differ from bombs in that they
 are from previous events and may be breciated
magmas, and that becomes then a problem to determine
origin other than terrestrial. Bombs on the other
hand, will usually be of freshly melted material and
can be very frothy in texture as well as having
aerodynamic forms. Both types can occur in an
eruption, but I'd expect ash to be the more common
found with old magma ejecta. Mark "


Ejected "old" magmas were basically what I was
talking about when speaking of volcano bombs. I live
in the west central part of the Lower Pensisula
which also answers Mark Langenfield's question. I
thought it was likely that if such rocks were here,
they would have been transported by glaciers rather
than by an ancient, nearby volcano! I brought them
up, wondering if they could bear some of the
characteristics of impact breccias.

Harald Stehlik (ABG) wrote:

"hope this helps a little bit... at which crater did
you find something ?"

If the rocks are indeed genuine (which I could be
entirely wrong on) they could be from an unknown
crater(s) . Once again thay were found in end
moraines on my family's farm, rather than from
exposed bedrock in or around a suspected impact
structure. In fact most of the Lower Pennsula is
covered by glacier till.
    
Mr. El Jones posted a reply to my orignal post, but
I haven't read it yet. I will try later.

Long strewn fields!

Mark Fox
Newaygo, MI USA

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Received on Wed 02 Apr 2003 09:21:32 AM PST