Geldmacher, Jörg

Heydolph, Ken

Hoernle, Kaj

Mahoney, John J.

Murphy, David T.

Romanova, Irina

English

OceanRep

CONTROL ID: 1482252 TITLE: Combined Sr, Nd, Pb and Hf isotopic constraints on the origin of Shatsky Rise (NW Pacific)  AUTHORS (FIRST NAME, LAST NAME): Joerg Geldmacher1, Ken Heydolph1, David T Murphy2, Irina R      Hoernle1 INSTITUTIONS (ALL): 1. Dynamics of the Ocean Floor, GEOMAR - Helmholtz Centre for Ocean Resear      2. School of Natural Resource Sciences, Queensland University of Technology, Gardens Point, QLD, Austral   3. Geology and Geophysics, School of Ocean and Earth Science and Technology, University of Hawaii, HI, U    ABSTRACT BODY: The submarine Shatsky Rise plateau in the northwest Pacific Ocean (ca. 1500 km east       Jurassic to Early Cretaceous. Based on magnetic reversals combined with bathymetric data, the three main vo       massifs are proposed to have successively formed by massive volcanism along a southwest-northeast moving       investigate a proposed interaction of a possible mantle plume head with the spreading system, Shatsky Rise w       in 2009 (Expedition 324 Scientists, 2010). Based on major and trace element compositions, the origin of the v        be explained by derivation from a normal mid-ocean ridge basalt (MORB)-like source, although a distinct de       implies that melting started at greater depth (Sano et al. in press). A small fraction of samples (all from Ori m       highly over moderately incompatible trace element ratios indicating an enriched (plume?) source.  We present compiled Sr, Nd, Pb and Hf isotope ratios from all three volcanic edifices of Shatsky Rise and wi          trace element study. Most isotope data overlap with Pacific MORB composition although regional variations        drill sites on the oldest edifice, Tamu massif, yield fairly uniform compositions, a wider spread is found for la        and Shirshov, suggesting that the source has become more heterogeneous with time (also consistent with the       reflect a decreasing degree of melting (and therefore less homogenization of inherent plume heterogeneities)       during the interaction of the spreading center with a waning plume head. Interestingly, lavas from the Ori and      143Nd/144Nd and 206Pb/204Pb ratios, placing them closer to a composition recently proposed for a non-cho     which is supposed to be preferentially sampled by large igneous province volcanism (Jackson and Carlson, 2   Expedition 324 Scientists, IODP Prel. Rept. 324, 2010  Jackson, M.G. and Carlson, R.W., Nature, vol. 476, 2011  Sano T., Shimizu K., Ishikawa A., Senda R., Chang Q., Kimura J.-I., Widdowson M., Sager W.W. Geochemi        KEYWORDS: [1040] GEOCHEMISTRY / Radiogenic isotope geochemistry, [1021] GEOCHEMISTRY / C       TECTONOPHYSICS / Hotspots, large igneous provinces, and flood basalt volcanism. (No Image Selected) (No Table Selected)  Additional Details Previously Presented Material: Some preliminary data (30%) were presented at last years AGU fall meetin         Contact Details CONTACT (NAME ONLY): Joerg Geldmacher CONTACT (E-MAIL ONLY): jgeldmacher@geomar.de TITLE OF TEAM:  

Combined Sr, Nd, Pb and Hf isotopic constraints on the origin of Shatsky Rise (NW Pacific)

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