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We investigate the influence of mantle flow relative to the lithosphere on subduction dynamics. We use 2D thermo-mechanical models assuming incompressible non-Newtonian fluid rheology. Different mantle flow velocities consistent with absolute plate motion models are tested, as well as both directions of flow, either sustaining or opposing slab dip. The effects of different inflow/outflow velocity profiles, slab strengths and upper–lower mantle viscosity contrasts are also evaluated. Slab dip deviations between models with opposite mantle flow directions range from 37° for relatively strong slabs (ηmax = 1025 Pa s) to 50° for weaker slabs (ηmax = 1024 Pa s), accounting for a significant amount of natural slab dip variability. For imposed mantle flow supporting the slab, the initial stage of slab steepening is followed by a stage of continuous slab dip decrease. This slab shallowing eventually leads to mantle wedge closure, subduction cessation and slab break-off, possibly driving subduction flips.

12 páginas, 11 figuras, 1 tabla., A Matlab tool for archaeomagnetic dating has been developed in this work. Well-dated palaeosecular variation curves (PSVCs) can be used to date archaeological artefacts with unknown ages. The archaeomagnetic direction (declination and/or inclination) and the archaeointensity obtained from the archaeological artefact are compared with a master PSVC. In addition, historical lava flows with controversial ages can be dated using this methodology. The dating process follows the descriptions given by Lanos (2004), which is based on the combination of temporal probability density functions of the three geomagnetic field elements. Here, we develop an interactive tool in Matlab code to carry out archaeomagnetic dating by comparing the undated archaeomagnetic (or lava flow) data with a master PSVC. The master PSVCs included with the Matlab tool are the different European Bayesian curves and those generated using both regional and global geomagnetic field models. A case study using all the PSVCs available in Europe and some undated archaeomagnetic data has been carried out to analyze how the different PSVCs affect the dating process. In addition, the dating uncertainty and the relocation error have been analyzed in the European region. Results show that some regional Bayesian PSVCs and the regional SCHA.DIF.3K archaeomagnetic model are the best choices to obtain an accurate date in Europe. Moreover, when it is available, the full geomagnetic field vector must be used for archaeomagnetic dating., The authors are grateful to the Spanish Research Project CGL2008-02203 and the FPI grant BES-2006-13488.