Description: The Samoan volcanic lineament has many features that are consistent with a plume-driven hotspot model, including the currently active submarine volcano Vailulu'u that anchors the eastern extremity. Proximity to the northern end of the Tonga trench, and the presence of voluminous young volcanism on what should be the oldest (∼5 my) western island (Savai'i) has induced controversy regarding a simple plume/hotspot model. In an effort to further constrain this debate, we have carried out geochronological, geochemical and isotopic studies of dredge basalts from four seamounts and submarine banks that extend the Samoan lineament 1300 km further west from Savai'i. 40Ar/39Ar plateau ages from Combe and Alexa Banks (11.1 my—940 km, and 23.4 my—1690 km from Vailulu'u, respectively) fit a Pacific age progression very well. The oldest volcanism (9.8 my) on Lalla Rookh (725 km from Vailulu'u) also fits this age progression, but a new age is much younger (1.6 my). Isotopically, these three seamounts, along with Pasco Bank (590 km from Vailulu'u), all lie within, or closely along extensions of, the Sr–Nd–Pb fields for shield basalts from the Eastern Samoan Province (Savai'i to Vailulu'u); this clearly establishes a Samoan pedigree for this western extension of the Samoan hotspot chain, and pushes the inception of Samoan volcanism back to at least 23 my. From geodetic reconstructions of the Fiji–Tonga–Samoa region, we show that the northern terminus of the Tonga arc was too far west of the Samoa hotspot up until 1–2 my ago to have been a factor in its volcanism. Young rejuvenated volcanism on Lalla Rookh and Savai'i may be related to the rapid eastward encroachment of the Trench corner. The Vitiaz Lineament, previously thought to mark a proto-Tongan subduction zone, was more likely created by the eastward propagation of the tear in the Pacific Plate at the northern end of the arc.

Description: TOPO-EUROPE addresses the 4-D topographic evolution of the orogens and intra-plate regions of Europe through a multidisciplinary approach linking geology, geophysics, geodesy and geotechnology. TOPO-EUROPE integrates monitoring, imaging, reconstruction and modelling of the interplay between processes controlling continental topography and related natural hazards. Until now, research on neotectonics and related topography development of orogens and intra-plate regions has received little attention. TOPO-EUROPE initiates a number of novel studies on the quantification of rates of vertical motions, related tectonically controlled river evolution and land subsidence in carefully selected natural laboratories in Europe. From orogen through platform to continental margin, these natural laboratories include the Alps/Carpathians–Pannonian Basin System, the West and Central European Platform, the Apennines–Aegean–Anatolian region, the Iberian Peninsula, the Scandinavian Continental Margin, the East-European Platform, and the Caucasus–Levant area. TOPO-EUROPE integrates European research facilities and know-how essential to advance the understanding of the role of topography in Environmental Earth System Dynamics. The principal objective of the network is twofold. Namely, to integrate national research programs into a common European network and, furthermore, to integrate activities among TOPO-EUROPE institutes and participants. Key objectives are to provide an interdisciplinary forum to share knowledge and information in the field of the neotectonic and topographic evolution of Europe, to promote and encourage multidisciplinary research on a truly European scale, to increase mobility of scientists and to train young scientists. This paper provides an overview of the state-of-the-art of continental topography research, and of the challenges to TOPO-EUROPE researchers in the targeted natural laboratories

Description: Lithospheric plates move over the low‐viscosity asthenosphere balancing several forces, which generate plate motions. We use a global 3‐D lithosphere‐asthenosphere model (SLIM3D) with visco‐elasto‐plastic rheology coupled to a spectral model of mantle flow at 300 km depth to quantify the influence of intra‐plate friction and asthenospheric viscosity on plate velocities. We account for the brittle‐ductile deformation at plate boundaries (yield stress) using a plate boundary friction coefficient to predict the present‐day plate motion and net rotation of the lithospheric plates. Previous modeling studies have suggested that small friction coefficients ( urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0001, yield stress urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0002 MPa) can lead to plate tectonics in models of mantle convection. Here we show that in order to match the observed present‐day plate motion and net rotation, the frictional parameter must be less than 0.05. We obtain a good fit with the magnitude and orientation of the observed plate velocities (NUVEL‐1A) in a no‐net‐rotation (NNR) reference frame with urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0003 and a minimum asthenosphere viscosity of urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0004 Pas to 1020 Pas. Our estimates of net rotation (NR) of the lithosphere suggest that amplitudes urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0005 ( urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0006/Ma), similar to most observation‐based estimates, can be obtained with asthenosphere viscosity cutoff values of urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0007 Pas to urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0008 Pas and friction coefficients urn:x-wiley:15252027:media:ggge21498:ggge21498-math-0009.