tag:blogger.com,1999:blog-3319786799012800176.post2886582817673193349..comments2023-10-13T03:51:03.655-04:00Comments on Magma Cum Laude: Volcanic claysJessica Ballhttp://www.blogger.com/profile/13117925212295349320noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-3319786799012800176.post-23058305517275939622010-03-12T20:04:25.019-05:002010-03-12T20:04:25.019-05:00Mel - Good catch. You're right - montmorilloni...Mel - Good catch. You're right - montmorillonites are a kind of smectite. (Guess the sentence was a little confusing that way.)Jessica Ballhttps://www.blogger.com/profile/13117925212295349320noreply@blogger.comtag:blogger.com,1999:blog-3319786799012800176.post-21459832464129769362010-03-12T15:45:40.389-05:002010-03-12T15:45:40.389-05:00Out of curiosity, why did you separate shrinking a...Out of curiosity, why did you separate shrinking and swelling clays into smectite and montmorillonite? Isn't montmorillonite a smectite clay? Just checking if I am missing something about clay classification...Melhttps://www.blogger.com/profile/09604241692429050566noreply@blogger.comtag:blogger.com,1999:blog-3319786799012800176.post-29825860363206363252010-02-25T20:51:03.073-05:002010-02-25T20:51:03.073-05:00Volcanic clays can be hazardous to science as well...Volcanic clays can be hazardous to science as well. A few years back, Petrobras drilled an exploration hole through the entire Brazilian Cryogenean sedimentary sequence. Geochronological cross-corellation of the neoptoterozoic glaciations is a big deal for understanding the Earth's surface environment at the time of multicellular radiation. And the drillers intersected several volcanic layers nicely bracketing the diamictites. Naturally, the Brazilian scientists were keen to use this to pin down the ages of the glaciations. So they ran the zircons from these ~650 Ma sediments. And what was the dominant zircon age population in each volcanic layer?<br /><br />2 million years.<br /><br />The drillers had used Andean bentonite as their drilling mud, introducing quaternary zircons into the entire sequence and contaminating all of their cuttings. The results were unpublishable.C W Mageehttps://www.blogger.com/profile/09706100504739548720noreply@blogger.comtag:blogger.com,1999:blog-3319786799012800176.post-52682628705405455362010-02-20T19:47:26.232-05:002010-02-20T19:47:26.232-05:00This is good stuff. I had no idea volcanoes could ...This is good stuff. I had no idea volcanoes could alter rock to the point of creating different types of clay. I love volcanoes!Anabellahttps://www.blogger.com/profile/02000590987317693751noreply@blogger.comtag:blogger.com,1999:blog-3319786799012800176.post-12589584849203793412010-02-20T11:28:52.605-05:002010-02-20T11:28:52.605-05:00Nice summary to extrusive minerals and their alter...Nice summary to extrusive minerals and their alteration products. I teach a soil mechanics class - another aspect of these shrink/swell clays is that they can impart unwanted lateral forces on retaining walls and foundations. And that susceptibility-to-shearing thing: no good for slope stability, especially when subject to loads from buildings.<br /><br />Although volcanic soils form one of my favorite soil taxa: "andisols."<br /><br />If it weren't for volcanoes (via plate tectonics) the only minerals we'd ever really see would be clays, transition/other metal oxides, and quartz (or other forms of silicon dioxide).Matt Kuchtahttps://www.blogger.com/profile/18168846490598155683noreply@blogger.com