Wits Geotalk - Deep crustal cumulates & calc-alkaline vs tholeiitic magma series - Grant Bybee 

Cool video. Consider placing the webcam frame elsewhere so the text in the bottom right will be visible.

Thanks for your presentation is gorgeous. I'm a geologist student and I'm working in a cumulate rock in my country but my geochemistry doesn't have a good percentage of Na, K and Ca. Could you explain that or classify it ? As well it's an antique subduction zone perhaps and volcanic arc. I appreciated your time, have a nice one