HR: 0800h
AN: V51A-1465    [Abstracts]
TI: Isotopic and Geochemical Characteristics of the Reunion Hotspot; Evidence From the Lavas of Mauritius
AU: * NOHDA, S
EM: snohda@sci.kumamoto-u.ac,jp
AF: Faculty of Sciences, Kumamoto University, Kurokami,2-39-1, Kumamoto, 860-8555 Japan
AU: Hanyu, T
EM: hanyut@jamstec,go.jp
AF: IFREE,JAMSTEC, natsushima-cho 2-15, yokosuka, 237-0061 Japan
AU: KANEOKA, I
EM: Ikaneoka@aol.com
AF: ERI, Univ.Tokyo, Bunkyo-ku, yayoi1-1-1, Tokyo, 113-0032 Japan
AB: We report Sr, Nd, and Pb isotopic compositions and trace-element concentrations for the lavas of Mauritius, the second youngest volcanic island in the Reunion hotspot. The lavas of the Older Series (7.8-5.5 Ma) represent the erosional remnants of a large shield volcano and have identical isotopic compositions with those of Reunion (170 km WSW of Mauritius) where the center of volcanic activity is currently located. The lavas of the Intermediate Series (3.5-1.9 Ma) and Younger Series (0.70-0.17 Ma) are the products of reactivated volcanic activities following each volcanic hiatus of 2 myr and 1.2 myr, respectively. The intermediate Series lavas have similar trace-element characteristics (e.g. Zr-Nb, Ba-Y) to those of Rodrigues (650 km ESE of Mauritius) due to probable channeled asthenospheric flow from the Reunion hotspot towards the Central-Indian Oceanic Ridge (CIR). It is plausible that such asthenospheric flow entrained the Reunion hotspot component in part, and also encountered an EM-like domain drifting within the asthenosphere during upwelling of the flow. About 0.5myr ago, when the hotspot was located 200 km to the southwest of Mauritius, the plume was still capable of supplying thermal energy to the surrounding CIR-source mantle by heat propagation due to the slow motion of the overlying African plate (3.7 cm/yr). Magmas of the Younger Series were derived from the outer zone of the plume, representing a mixture of plume and MORB-source mantle.
DE: 8411 Thermodynamics (0766, 1011, 3611)
DE: 8415 Intra-plate processes (1033, 3615)
DE: 8434 Magma migration and fragmentation
DE: 9340 Indian Ocean
DE: 9604 Cenozoic
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005