What is the reason of high Al2O3 and low CaO whole rock content of mantle peridotites?

I have whole rock mantle peridotite (harzburgite and dunite) analyse results (ICP-ES) from ACME (Canada) and Academia Sinica (Taiwan). There are three samples problematic for me. I need to explain...

05 March 2020 7,147 22 View