The influence of mantle dynamic processes on the noble gas isotopic composition of oceanic island basalts (OIBs)

• Applicant: Dr. Nicole Stroncik
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2005 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5452167

He isotopes are still one of the main tracers for the identification of mantle reservoirs and mantle dynamics. Basic concepts on mantle structure and evolution, such as two-layer mantle convection or any other “layered mantle model”, are primarily based on the interpretation of mantle 3He as reflecting primordial, undegassed mantle material. In this context the isotopic variability observed in ocean island basalts (OIBs) from individual mantle plume regions is usually related to mixing of different mantle reservoirs. Little is known about the contribution of magmatic processes to those heterogeneities. Without an understanding of these processes and their contribution to geochemical parameters it is hard to precisely explain the composition and evolution of the Earth’s mantle. Thus the proposed continuation of the project is focused on the detailed study of the noble gas isotope composition of fresh, submarine basalts from the Easter and Foundation plumes to determine the magmatic processes influencing the noble gas isotopic composition of a magmatic rock. During the current funding period we have established that the noble gas isotopic compositions of Easter and Foundation magmas are extensively altered by magmatic processes. However, we are not able with our current data base to develop a general model on the timing and on the exact processes affecting noble gas isotopes during magmatic evolution.

• DFG Programme: Research Grants