Plume versus plate origin for the Shatsky Rise oceanic plateau (NW Pacific): Insights from Nd, Pb and Hf isotopes

Heydolph, Ken, Murphy, David T., Geldmacher, Jörg, Romanova, Irina V., Greene, Andrew, Hoernle, Kaj, Weis, Dominique and Mahoney, John (2014) Plume versus plate origin for the Shatsky Rise oceanic plateau (NW Pacific): Insights from Nd, Pb and Hf isotopes Lithos, 200-201 . pp. 49-63. DOI 10.1016/j.lithos.2014.03.031.

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Shatsky Rise, an early Cretaceous igneous oceanic plateau in the NWPacific, comprises characteristics that could
be attributed to either formation by shallow, plate tectonic-controlled processes or to an origin by a mantle
plume(head). The plateauwas drilled during Integrated Ocean Drilling Program(IODP) Expedition 324. Complementary
to a recent trace element study (Sano et al., 2012) this work presents Nd, Pb and Hf isotope data of recovered
lava samples cored from the three major volcanic edifices of the Shatsky Rise. Whereas lavas from the
oldest edifice yield fairly uniform compositions, awider isotopic spread is found for lavas erupted on the younger
parts of the plateau, suggesting that the Shatsky magma source became more heterogeneous with time. At least
three isotopically distinct components can be identified in the magma source: 1) a volumetrically and spatially
most common, moderately depleted component of similar composition to modern East Pacific Ridge basalt but
with low 3He/4He, 2) an isotopically very depleted component which could represent local, early Cretaceous
(entrained) depleted upper mantle, and 3) an isotopically enriched component, indicating the presence of
(recycled) continental material in the magma source. The majority of analyzed Shatsky lavas, however, possess
Nd–Hf–Pb isotope compositions consistent with a derivation from an early depleted, non-chondritic reservoir.
By comparing these results with petrological and trace element data of mafic volcanic rock samples from all
three massifs (Tamu, Ori, Shirshov), we discuss the origin of Shatsky Rise magmatism and evaluate the possible
involvement of a mantle plume (head).

Document Type: Article
Keywords: Shatsky Rise; Hard rock samples from IODP Expedition 324; Mantle plume or triple junction origin; Nd–Pb–Hf isotope geochemistry
Research affiliation: Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
DOI etc.: 10.1016/j.lithos.2014.03.031
ISSN: 0024-4937
Projects: IODP
Date Deposited: 17 Jun 2014 08:05
Last Modified: 12 Sep 2017 13:53

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