Anorthosites

Petrogenesis of Proterozoic massif-type anorthosites

Isotopic studies of massif-type anorthosites in the rapakivi suite of Southern Finland and Northern Brazil were the main topic of my PhD thesis project that was finished in 2012. I have continued to work on diverse, more restricted mineralogical and petrological problems in the main anorthosite location of southern Finland, the Ahvenisto complex, with some of my students.

Isotopic evidence for the petrogenesis of massif-type anorthosites in southern Finland and northern Brazil
In my PhD thesis I have summarized the isotope geochemical studies conducted in the Ahvenisto complex of southern Finland and the Mucajaí complex in the state of Roraima in northern Brazil. The central findings of these studies pertain to the source controversy of massif-type anorthosites; are they ultimately mantle-derived and if so, what is the nature of the mantle component. The results are summarized in the synopsis of my PhD-thesis that can be accessed here.

High-aluminum orthopyroxene megacrysts (HAOM) in the Ahvenisto complex
Hig-aluminum orthopyroxene megacrysts, or HAOM's for short, have been utilized in geobarometric studies of massif-type anorthosites. HAOM localities and types in Ahvenisto were mapped and studied in a student project during years 2013-2015 by Heli Kivisaari. The project was reported in a MSc thesis in 2015 and a global mineral chemical comparison based on Heli's work is still on-going.

Monzodiorites and magma interaction in the Ahvenisto complex
This sub-project has branched into its own project. More info behind the link...