1. Geochemical Signatures of Recycled Ancient Carbonates in the Hawaiian Plume Shichun Huang Harvard May 19, 2009 CIDER Co-workers: J. Blichert-Toft D. A. Clague B. Cousens W. Abouchami J. Farkas F. A. Frey M. Humayun S. B. Jacobsen Hawaii Aleutian Trench Koolau Mahukona

2. Within Mahukona, Nd-Hf-Pb isotopic ratios are highly correlated with each other; but 87 Sr/ 86 Sr is decoupled from other isotopes. Huang et al., in revision

3. 87 Sr/ 86 Sr is correlated with trace element abundance ratios involving Sr, implying a Sr-rich source component for Mahukona lavas. Huang et al., in revision

4. Hawaiian shield lavas form a negative Rb/Sr- 87 Sr/ 86 Sr trend, implying that recycled ancient carbonate was sampled by all Hawaiian shield volcanoes. Huang et al., in revision Farkas et al., in prep. Koolau  44 Ca/ 40 Ca = ( 44 Ca/ 40 Ca sample / 44 Ca/ 40 Ca SRM915a -1)*1000

5. Huang, unpublished data Makapuu-stage Koolau lavas have 44 Ca/ 40 Ca lower than typical mantle value. The low 44 Ca/ 40 Ca in Makapuu-stage Koolau lavas can be explained as a result of sampling 2-6% recycled ancient carbonate sediment.

6. Conclusion The negative Rb/Sr- 87 Sr/ 86 Sr trend formed by Hawaiian shield lavas implies that recycled ancient carbonate-rich sediment is present in the Hawaiian plume. The presence of recycled ancient carbonate (up to 6%) in the Hawaiian plume is further confirmed by the low 44 Ca/ 40 Ca in Makapuu-Stage Koolau lavas. The presence of ancient surface geochemical signatures (high  18 O, low Rb/Sr coupled with high 87 Sr/ 86 Sr, and low 44 Ca/ 40 Ca) in the deeply originated Hawaiian plume implies whole mantle convection.