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Abstract. Melt generation in a rifting environment is studied using a dynamic 2-D finite elmnent model. The lithosphere is extended to large, realistic thinning factors assuming a mantle temperature of 1333øC. The lbcussing of deformation results in a distribution of thinning factors along the margin at breakup time consistent with observations. The timing of melt production (late synrift) and the amounts of melt are consistent with observations at volcanic •nargins. The dynmnical processes related to lithospheric rifting enhance t, he produced melt volumes sufficiently to explain the sometimes enigmatic melt volumes fbund at volcanic 1ha.r-

SUMMAR YThe Ebro Basin, the southern foreland basin of the Pyrenees, has undergone a complex evolution in which, apart from the Pyrenees, the Iberian Range and the Catalan Coastal Ranges have played an important role, both as sediment sources and as basin confining structures. The deflected basement underlying the Ebro Basin dips north, suggesting a lithospheric-scale control on the structure of this basin. This is compatible with the results of subsidence analyses, which show that the study area is not in a local mode of isostatic compensation.In order better to understand the mechanisms that led to the present configuration of the Ebro Basin, and particularly the relevance of the various kinds of (un)loading (e.g. surrounding fold-and-thrust belts, basin topography, subsurface loads), we carried out a 3-D kinematic modelling study that accounts for the flexural state of the lithosphere, subjected to various loads applied at its lateral boundaries, and the sedimentary fill of the basin. We also included the effect of Neogene extensional tectonics along the eastern basin margin, which is related to the opening of the Valencia Trough.We show the suitability of the 3-D lithospheric-scale flexural modelling approach to the study of NE Iberia. Modelling results point to a relatively strong lithosphere in this area, with values of effective elastic thickness ranging from 10 to 35 km in the Ebro Basin, increasing towards the Pyrenees. We also find that the topographic (tectonic) load itself is insufficient to explain the observed basement deflection. Thus an extra subsurface load beneath the Pyrenees, corresponding to the underthrusted Iberian lithosphere, is required. The effect of lithospheric stretching in the Valencia Trough on the Ebro Basin is appreciable only in its eastern part, where the lithosphere was uplifted. This had considerable repercussions on the sedimentary and erosional regime of the Ebro Basin. We have analysed the link between the stretching-related, tectonically uplifted areas and the erosional patterns observed onshore northeast Iberia.

[1] Apatite (U-Th)/He and fission track age determinations of samples from a 20-km-long, nearhorizontal tunnel in the Hochalm-Ankogel Dome (eastern Tauern Window, Austria) are presented in order to determine the role of (paleo)-topography in perturbing isotherms in the shallow crust. Apatite fission track ages show no systematic correlation with distance along the tunnel or elevation. Two age components in the fission track data indicate cooling through $120°C at approximately 20 Ma and $80°C at approximately 6 Ma. Surface and tunnel (UTh)/He ages (17-9 Ma and 13-5 Ma, respectively) are consistently younger than the equivalent fission track ages. (U-Th)/He ages vary systematically along the tunnel with older ages at the northern and southern tunnel portals and younger ages in the central section. Geological factors (faulting, lithology) appear to have had little effect on this age distribution. The (U-Th)/He age pattern is inconsistent with rock cooling underneath the present-day Hochalm-Ankogel Dome topography. The age minimum is interpreted to coincide with a paleotopographic maximum in the Hochalm-Ankogel Dome and suggests that the 40-60°C isotherms were warped sufficiently to affect apatite (U-Th)/He ages. The tunnel apatite (U-Th)/He ages match synthetic He ages derived from a twodimensional numerical model of landscape evolution. Integrating the thermal model results with the data allows the relief development to be constrained and we calculate that the present-day Hochalm-Ankogel Dome topography was formed at 7 to 10 Ma.