"Mantle sources and magma evolution: Insights from melt inclusion and mineral geochemistry"

Mike Rowe
Univ. of Iowa

 

Abstract: Olivine-hosted melt inclusions in primitive basalts provide unique constraints on our understanding of magma source regions and magmatic evolution. The addition of volatiles and fluid soluble elements to the lithospheric mantle can have a significant impact on melt generation and magma chemistry/mineralogy. However, in subaerially erupted magmas, volatiles (CO2, H2O, S, Cl, and F) are lost during degassing. These volatiles may be retained in melt inclusions which remain isolated from the magma body, thus providing the only direct means of measuring magma volatile concentrations prior to eruption. Additionally, because mineral compositions will evolve as the host magma evolves, melt inclusions trapped within continuously evolving minerals should record a relative sequence of magma evolution that is ultimately lost in the final, homogenized erupted product. This presentation will cover several examples of melt inclusion studies ranging from mantle metasomatism beneath the Oregon Cascades to shallow magmatic evolution and degassing of Paricutin volcano, Mexico.