The magmatic and geochemical evolution of oceanic intraplate volcanoes: constraints from the Louisville Seamounts (IODP Leg 330) and other Pacific hotspots
Final Report Abstract
The main aims of this project were to improve our understanding of the evolution of oceanic intraplate volcanoes with an emphasis on glasses and lavas sampled from the Louisville Seamount Chain during IODP Leg 330 in previous cruises. We can show that much of the small along-chain variability of the Louisville seamounts may best be explained by changes in the melting regime as a result of a thickening lithosphere. Post-erosional glasses from two drill sites imply slightly decreasing degrees of partial melting because the volcanic edifice was moving away from the main source of melting. The variability of other Pacific intraplate systems, e.g., in Hawaii, the Marquesas and Society islands exceeds that observed in the Louisville seamounts. These islands formed on lithosphere with comparable thickness and hence much of the observed variability is the result of changes in source composition and melting regime. We suggest that the mantle source heterogeneity may best be preserved in melting anomalies which display a smaller buoyancy flux (e.g., the Marquesas and Societies) while those that have a much larger buoyancy flux (e.g., Hawaii) may result in a more extensive melting regime which may blur much of the original heterogeneity of the mantle. Our observations imply that considerable care has to be taken when comparing different island groups in major element, trace element and radiogenic isotope spaces.
Publications
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2014. Geochemistry of volcanic glasses from the Louisville Seamount Trail (IODP Expedition 330): Implications for eruption environments and mantle melting. Geochemistry, Geophysics, Geosystems 15
Nichols, A.R.L., Beier, C., Brandl, P.A., Buchs, D.M. & Krumm, S.H.
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2014. Louisville Seamount Chain: Petrogenetic processes and geochemical evolution of the mantle source. Geochemistry, Geophysics, Geosystems 15
Vanderkluysen, L., Mahoney, J.J., Koppers, A.A.P., Beier, C., Regelous, M., Gee, J.S. & Lonsdale, P.F.
