Open AccessGeochemical stages at Jasper Seamount and the origin of intraplate volcanoes
Author(s) -
Konter J. G.,
Staudigel H.,
BlichertToft J.,
Hanan B. B.,
Polvé M.,
Davies G. R.,
Shimizu N.,
Schiffman P.
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2008gc002236
Subject(s) - geology , seamount , mantle (geology) , intraplate earthquake , trace element , volcano , geochemistry , submarine volcano , primitive mantle , radiogenic nuclide , partial melting , paleontology , tectonics
Ocean intraplate volcanoes (OIVs) are formed in a sequence of stages, from large to small, that involve a systematic progression in mantle melting in terms of volumes and melt fractions with concomitant distinct mantle source signatures. The Hawaiian volcanoes are the best‐known example of this type of evolution, even though they are extraordinarily large. We explore the Pb‐Sr‐Nd‐Hf isotopic evolution of much smaller OIVs in the Fieberling‐Guadalupe Seamount Trail (FGST) and small, near‐ridge generated seamounts in the same region. In particular, we investigate whether we can extend the Hawaiian models to Jasper Seamount in the FGST, which displays three distinct volcanic stages. Each stage has characteristic variations in Pb‐Sr‐Nd‐Hf isotopic composition and trace element enrichment that are remarkably similar to the systematics observed in Hawaii: (1) The most voluminous, basal “shield building” stage, the Flank Transitional Series (FTS), displays slightly isotopically enriched compositions compared to the common component C and the least enriched trace elements ( 143 Nd/ 144 Nd: 0.512866–0.512909, 206 Pb/ 204 Pb: 18.904–19.054; La/Sm: 3.71–4.82). (2) The younger and substantially less voluminous Flank Alkalic Series (FAS) is comparatively depleted in Sr, Nd, and Hf isotope compositions plotting on the side of C, near the least extreme values for the Austral Islands and St. Helena. Trace elements are highly enriched ( 143 Nd/ 144 Nd: 0.512912–0.512948, 206 Pb/ 204 Pb: 19.959–20.185; La/Sm: 9.24). (3) The Summit Alkalic Series (SAS) displays the most depleted Sr, Nd, and Hf isotope ratios and is very close in isotopic composition to the nearby near‐ridge seamounts but with highly enriched trace elements ( 143 Nd/ 144 Nd: 0.512999–0.513050, 206 Pb/ 204 Pb: 19.080–19.237; La/Sm: 5.73–8.61). These data fit well with proposed multicomponent melting models for Hawaii, where source lithology controls melt productivity. We examine the effect of melting a source with dry peridotite, wet peridotite, and pyroxenite, calculating melt productivity functions with depth to evaluate the effect of potential temperature and lithospheric thickness. This type of melting model appears to explain the isotopic variation in a range of small to large OIVs, in particular for OIVs occurring far from the complicating effects of plate boundaries and continental crust, constraining their geodynamic origin.