Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Chemistry
Biology and Medical
Earth Sciences
Computer Science
Computing and Technology
DIY Projects
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Search titles only
By:
Chemistry
Biology and Medical
Earth Sciences
Computer Science
Computing and Technology
DIY Projects
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Other Sciences
Earth Sciences
Iceland earthquakes, 18000 in a week Fagradalsfjall Volcano
Reply to thread
Message
[QUOTE="DrDu, post: 6586808, member: 210532"] During vacations I found some time to look at the plagioclase in the basalt under the microscope using a so-called "universal stage" which allows to rotate the thin section around 4 axes, see the picture. This makes it possible to determine the orientations of the principal optical axes relative to some characteristic crystal faces. As these orientations are known as a function of the composition of the plagioclase, namely the albite (NaAlSi3O8)-anorthite (CaAl2Si2O8) ratio, it is possible to estimate this ratio quite accurately without the necessity to do a chemical analysis or a X-ray microprobe analysis. It turned out that the plagioclase is about 95% anorthite, which is what one would expect for a MORB. In comparison to albite, anorthite contains less SiO2 and is therefore said to be more basic. The low SiO2 content means that the temperature, where crystals begin to form in the lava is quite high, and the viscosity of the lava is low. This is in line with pictures where the lava can be seen to flow like water. The high anorthite content also points to the lava being quite primitve, meaning that it is still quite similar to the primary magma that formed when the mantle material melted. So quite a lot can already be learned about this kind of rocks without high-tech equipment. [/QUOTE]
Insert quotes…
Post reply
Forums
Other Sciences
Earth Sciences
Iceland earthquakes, 18000 in a week Fagradalsfjall Volcano
Back
Top