[meteorite-list] meaning of breccia
From: Dave Gheesling <dave_at_meteoritecentral.com>
Date: Tue, 10 May 2011 00:50:33 -0400 Message-ID: <A31D4DF0D8FD408AA39345EE1E684ADC_at_meteorroom> Thanks for this post, Dr. Rubin. Sent my earlier comments too quickly, and was more focused on the fact that list members like you should be commenting on these sorts of things anyway -- and that private collectors shouldn't be quoted (misquoted, in this event, or actually quoted when no prior quote existed at all) as if their supposed opinion matters much anyway. All the best, Dave www.fallingrocks.com -----Original Message----- From: aerubin at ucla.edu [mailto:aerubin at ucla.edu] Sent: Tuesday, May 10, 2011 12:23 AM To: dave at fallingrocks.com Cc: cdtucson at cox.net; 'meteoritelist'; 'Greg' Subject: Re: [meteorite-list] meaning of breccia Just a clarification of the word breccia. A breccia is a rock that contains distinct chunks or clasts. If the clasts are all of the same lithology and the host is the same lithology as the clasts, the rock is a monomict breccia. If the clasts or hosts are from different meteorite groups, the rock is a polymict breccia. Wasson coined the term "genomict breccia" for chondrites that have clasts from the same group but of different petrologic types (e.g., L5 and L6 clasts in an L-chondrite host). A regolith breccia is a rock from the surface of its parent body. A prime example is the H-chondrite Dimmitt. In addition to H4 and H5 clasts,the Dimmitt host contains some H3 material. There are also some carbonaceous chondrite clasts (CM and unspecified C3) and an LL5 clast. Regolith breccias are also typically rich in solar-wind-implanted rare gases and may contain mineral grains with solar-flare particle tracks. Received on Tue 10 May 2011 12:50:33 AM PDT |
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