[meteorite-list] impactite vs. impact glass
From: Dennis Harries <dennis_harries_at_meteoritecentral.com>
Date: Thu Apr 22 10:23:50 2004 Message-ID: <BAY1-F144RPmcarcR4Z00047848_at_hotmail.com> <html><div style='background-color:'><DIV></DIV> <P>Hello Bob and all,</P> <P>Probably this nomenclature is applicable to all kinds of impact related rocks, as are meteorites.</P> <P>It seem to me that the term 'impact melt breccia' should be discarded, because it is usually NOT a brecciated impact melt rock set in a clastic or igneous matrix, but clasts of non melted rock set in a molten matrix. Usually the term accompaning 'breccia' refers to the nature of the clasts itselves, not to the nature of the matrix. So the more correct term for 'impact melt breccia' would be 'impact melt rock' or 'impact melt rock with lithic clasts'. Thatīs how I understood it.</P> <P>In a singles impact event the melting and solidification of a rock can not predate the formation of a breccia of this material due to the same impact event. So truly (impact) brecciated impact melt rocks (=impact melt breccias) are extremly rare on earth, but elsewhere???? (an impact melt rock may be brecciated by another impact event, if it is monomict, it is an impact melt breccia, if it is polymict it is something else, maybe a lithic breccia or a regolith breccia...). Well, I hope I got it right, scientists seem to love that ;-) </P> <P>Best wishes</P> <P>Dennis Harries</P> <P>*NO WAR*</P> <P> </P> <P>>http://www.bgs.ac.uk/SCMR/docs/paper_12/scmr_paper_12_5.pdf </P> <DIV></DIV>> <DIV></DIV>>Hello Dave and Dennis and all, <DIV></DIV>> <DIV></DIV>>This USGS paper raises more questions. <DIV></DIV>> <DIV></DIV>>Under the term "Impact Melt Breccia" it recommends <DIV></DIV>>that it's use be "discarded"! <DIV></DIV>> <DIV></DIV>>It doesn't suggest a replacement term. It's not <DIV></DIV>>obvious to me what the new term should be, so could <DIV></DIV>>someone tell me, what is the "preferred" term? <DIV></DIV>> <DIV></DIV>>Since the author is Stoffler, I'm assuming these terms <DIV></DIV>>are applicable for use in describing meteorites. But <DIV></DIV>>this may not be the case. I may be wrong in my <DIV></DIV>>assumption, and this list of terms may be only <DIV></DIV>>applicable for metamorphic processes involving Terran, <DIV></DIV>>Lunar, and Martian impact events and their resultant <DIV></DIV>>impactites. <DIV></DIV>> <DIV></DIV>>Is there a separate list of "approved" terms for <DIV></DIV>>asteroidal impact events and meteorites? <DIV></DIV>> <DIV></DIV>>More questions still, <DIV></DIV>>BOb V. <DIV></DIV>> <DIV></DIV> <DIV><FONT style="BACKGROUND-COLOR: #fffbf0"></FONT></DIV></div><br clear=all><hr>MSN 8 helps <a href="http://g.msn.com/8HMSEN/2743">ELIMINATE E-MAIL VIRUSES. </a> Get 2 months FREE*.</html> Received on Sat 22 Mar 2003 04:10:50 AM PST |
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