Before my winter holiday I ran my samples under the electron micro-probe at the University of Western to analyze the plagioclase and volcanic glass. Each flow showed the volcanic glass isn't entirely glass, instead micro-textures show some minerals failing to develop: olivines are skeletal and mafic minerals are found nucleating off elongated plagioclase crystals.
The textures show quenched features which occurs if the lava flow cooled rapidly; minerals unable to develop under quick cooling rates resulting in incomplete chaotic micro-textures.
Devil's Orchard lava plagioclase minerals exhibit zonation of Ca, Na, K, Al and Ba. The barium content correlates positively with potassium and sodium and negatively with calcium. This is an expected occurre
nce with plagioclase if they continue to differentiate in the lava before crystallization is complete. This is observed across the entire flow but the zonation is more developed close to the vent.
As I mentioned in my first blog post I planned to analyze zonation features present in plagioclase crystals to understand the geochemical evolution of the lava flows. This is what I am currently working on before I attend the 48th LPSC meeting in March 2017.
Results are displayed on a separate powerpoint presentation.