Combined Lithophile‐Siderophile Isotopic Constraints on Hadean Processes Preserved in Ocean Island Basalt Sources

Length scales of mantle heterogeneities and their relationship to ocean island basalt geochemistry

The upper mantle is widely considered to be heterogeneous, possibly comprising a “marble-cake” mixture of heterogeneous domains in a relatively well-mixed matrix. The extent to which such domains are capable of producing and expelling melts with characteristic geochemical signatures upon partial melting, rather than equilibrating diffusively with surrounding peridotite, is a critical question f...

Along-Strike Trace Element and Isotopic Variation in Aleutian Island Arc Basalt: Subduction Melts Sediments and Dehydrates Serpentine

Isotopic Constraints on Biogeochemical Cycling of Fe

INTRODUCTION Cycling of redox-sensitive elements such as Fe is affected by not only ambient Eh-pH conditions, but also by a signifi cant biomass that may derive energy through changes in redox state (e. The evidence now seems overwhelming that biological processing of redox-sensitive metals is likely to be the rule in surface-and near-surface environments, rather than the exception. The Fe redo...

Major element variations in Hawaiian shield lavas: Source features and perspectives from global ocean island basalt (OIB) systematics

[1] Among volcanic hot spots globally, Hawaii has the highest magma flux, yet there is significant controversy surrounding the composition of the mantle sourcing Hawaiian lavas. In order to place constraints on the source lithologies of Hawaiian lavas, we explore relationships between major elements and radiogenic isotopes in tholeiitic, shield-building lavas. Olivine-fractionation corrected la...

THE SOURCES OF ISLAND ARCS AS INDICATED BY Nd AND Sr ISOTOPIC STUDIES

Abstmct: Island arc lavas from New Britain and the Marianas have 143 Nd/144 Nd similar to other oceanic basalts and distinctly different from continental flood basalts and thus appear to be derived from a high Sm/Nd, light-REE-depleted reservoir. Consideration of both Nd and Sr isotopes suggests seawater involvement in the generation of some island arc lavas and thus indicates that they may be ...