Mantle temperature variations beneath back-arc spreading centers inferred from seismology, petrology, and bathymetry

Publication Type  Journal Article
Year of Publication  2006
Authors  Wiens, D. A.; Kelley, K. A.; Plank, T.
Journal Title  Earth and Planetary Science Letters
Volume  248
Issue  1-2
Pages  30-42
Journal Date  Aug 15
ISBN Number  0012-821X
Accession Number  ISI:000240851400003
Key Words  back-arc basin basalts; upper mantle structure; mantle temperature; lau basin; mariana trough; major element systematics; ridge basalt chemistry; wave-form inversion; east scotia ridge; mariana trough; lau basin; southwest pacific; midocean ridges; global

Variations in seismological structure, major element composition, and axial depth between different back-arc spreading centers provide constraints on physical conditions associated with back-arc melt production. We invert vertical and transverse seismograms from several representative paths traversing the Mariana, Lau, North Fiji, and East Scotia back-arc basins. Seismic velocity varies substantially at depths of 40-100 km, with differences of up to 7% between the slowest (Lau) and the fastest (Mariana) structures. These mantle seismological structures correlate with major element systematics and the elevations of the ridge axes, consistent with differences in average upper mantle temperatures. In contrast to the temperature correlation, mantle seismic structure shows no apparent correlation with petrologically inferred water content. Petrological indicators suggest a similar to 100 degrees C range in mantle potential temperature, consistent with the seismic velocity variations, assuming experimentally determined temperature derivatives. The temperature variations, however, must extend throughout the upper similar to 200 km of the mantle wedge to produce the observed ridge elevation differences. Fast stab rollback and the influx of hot Samoan mantle may contribute to high temperatures in the Lau Basin. (c) 2006 Elsevier B.V. All rights reserved.


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URL  <Go to ISI>://000240851400003
DOI  DOI 10.1016/j.epsl.2006.04.011