Submarine back-arc lava with arc signature : Fonualei Spreading Center, northeast Lau Basin, Tonga
Keller, Nicole S.
Arculus, Richard J.
MetadataShow full item record
We present major, volatile, and trace elements for quenched glasses from the Fonualei Spreading Center, a nascent spreading system situated very close to the Tofua Volcanic Arc (20 km at the closest), in the northeast Lau Basin. The glasses are basalts and basaltic andesites and are inferred to have originated from a relatively hot and depleted mantle wedge. The Fonualei Spreading Center shows island arc basalt (IAB) affinities, indistinguishable from the Tofua Arc. Within the Fonualei Spreading Center no geochemical trends can be seen with depth to the slab and/or distance to the arc, despite a difference in depth to the slab of >50 km. Therefore we infer that all the subduction-related magmatism is captured by the back arc as the adjacent arc is shut off. There is a sharp contrast between the main spreading area of the Fonualei Spreading Center (FSC) and its northernmost termination, the Mangatolu Triple Junction (MTJ). The MTJ samples are characteristic back-arc basin basalts (BABB). We propose that the MTJ and FSC have different mantle sources, reflecting different mantle origins and/or different melting processes. We also document a decrease in mantle depletion from the south of the FSC to the MTJ, which is the opposite to what has been documented for the rest of the Lau Basin where depletion generally increases from south to north. We attribute this reverse trend to the influx of less depleted mantle through the tear between the Australian and the Pacific plates, at the northern boundary of the Lau Basin.
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): B08S07, doi:10.1029/2007JB005451.
Suggested CitationJournal of Geophysical Research 113 (2008): B08S07
Showing items related by title, author, creator and subject.
Rare earth element abundances in hydrothermal fluids from the Manus Basin, Papua New Guinea : indicators of sub-seafloor hydrothermal processes in back-arc basins Craddock, Paul R.; Bach, Wolfgang; Seewald, Jeffrey S.; Rouxel, Olivier J.; Reeves, Eoghan P.; Tivey, Margaret K. (2010-05-02)Rare earth element (REE) concentrations are reported for a large suite of seafloor vent fluids from four hydrothermal systems in the Manus back–arc basin (Vienna Woods, PACMANUS, DESMOS and SuSu Knolls vent areas). Sampled ...
Craddock, Paul R.; Bach, Wolfgang (2010-06-16)Microchemical analyses of rare earth element (REE) concentrations and Sr and S isotope ratios of anhydrite are used to identify sub–seafloor processes governing the formation of hydrothermal fluids in the convergent ...
Geochemical tracers of processes affecting the formation of seafloor hydrothermal fluids and deposits in the Manus back-arc basin Craddock, Paul R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2009-02)Systematic differences in trace element compositions (rare earth element (REE), heavy metal, metalloid concentrations) of seafloor vent fluids and related deposits from hydrothermal systems in the Manus back–arc basin ...