The noble view of early Earth history and mantle dynamics
IPGP - Îlot Cuvier
Séminaires généraux de l’IPGP
The noble gases provide important constraints for planet accretion models and mantle structure and dynamics. I will present new high-precision noble gas (Ne, Ar, Xe) data from Iceland and Northern Lau Basin, that suggest differences in noble gas abundance ratios, I/Xe ratios, and Pu/U ratios between MORBs and OIBs. Our results indicate that the plume source is less degassed then the MORB source and the differences in the degree of degassing must have existed within the first 100 Myrs. However, unlike some recent suggestions, we find no evidence for substantial recycling of atmospheric noble gases into the plume source. While the interpretation of our new data is compatible with limited mixing between the MORB and plume sources based on geochemical reservoir modeling, they are at odds with many of the dynamical models of mantle convection.