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The Rioja Trough is the foreland basin of the western Pyrenees (to the north) and the Cameros‐Demanda Massif (to the south). This E–W elongated trough is about 120×35 km. It was filled with Tertiary continental deposits (upper Eocene to upper Miocene), reaching thicknesses between 2500 and 5000 m. Both margins of the Rioja Trough are large thrusts with horizontal displacements of more than 20 km basinward. Rocks that fill the basin originated in alluvial fan and playa‐lake environments, with conglomerates in the proximal sectors grading into sandstones, mudstones, lacustrine limestones and evaporites in distal sectors. The Tertiary series are horizontal in the central parts of the basin, with several E–W monoclines caused by north‐verging thrusts in the basement of the basin. Near the basin margins, the Tertiary units are folded and thrusted, with several syntectonic unconformities. Calculated velocities for the Cameros‐Demanda thrust range from 0.02 to1.1 mm yr−1 (average 0.7 mm yr−1). The sedimentation rate near the southern basin margin varies between 2 and 20 cm 1000 yr−1 (average 10 cm 1000 yr−1). Deposition in the Rioja Trough was strongly controlled by tectonic activity throughout the Tertiary. Eight tectosedimentary units (R1 to R8) have been characterized. These are bounded by angular unconformities at the margins and breaks in the vertical trend of the sedimentary record toward the basin centre. Every tectosedimentary unit (except R6 and R8) shows a fining‐upward/coarsening‐upward trend, corresponding to tectonic retrogradations and progradations, respectively. The main source area during the Palaeogene was the Cameros‐Demanda Massif, whose unroofing sequence was strongly dependent on tectonic activity. During the Neogene a longitudinal WNW–ESE drainage system, with short alluvial fans in the northern and southern margins, developed. The final shape and the evolution of the Rioja Trough are the result of crustal flexure in the northern border of the Iberian plate, linked to the emplacement of the southern Pyrenean thrust system, and intraplate thrusting with basement uplift at its southern margin.

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Syn-tectonic remagnetizations related to burial processes that occurred during their extensional stage are frequently recognized in inverted sedimentary basins. The incremental fold test is the main analytical tool used to detect these syn-tectonic remagnetizations. However this test gives spurious results when asymmetrical folding occurs (i.e. both limbs were not tilted simultaneously at the same rate). Asymmetrical folding is very common in sedimentary basins, especially at their margins, during the basinal stage and subsequent tectonic inversion. To correctly analyse syn-tectonic remagnetizations in these scenarios, we propose a method to restore palaeomagnetic vectors, which allows determining the tilting of beds at the remagnetization stage and therefore gives some hints on the geometry of sedimentary basins and/or folds at the overprint acquisition time. In this paper we consider the analysis of syn-tectonic remagnetization directions for basin reconstruction in two end-member basin models (i.e. syncline vs roll-over geometry). Finally, we compare the results obtained with several northern Iberian examples (Cameros basin in the Iberian Chain, Cabuérniga and Polientes Basin in the Pyrenées), formed during the Mesozoic as extensional basins and subsequently inverted during the Cenozoic compression. From these examples we propose generalizations for the application of syn-tectonic remagnetizations to constrain the geometry of sedimentary basins.

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The geometry and emplacement of the ~ 96 km 2 , Late Cretaceous Sintra Igneous complex (SIC, ca. 80 Ma) into the West Iberian passive margin is presented, based on structural data, gravimetric modeling, and magnetic fabrics. A granite laccolith (~ 76 km 2 , < 1 km thick, according to gravimetric modeling) surrounds a suite of gabbro-diorite-syenite plugs (~ 20 km 2 , ~ 4 km deep) and is encircled by cone sheets and radial dykes. Anisotropy of Magnetic Susceptibility was interpreted from 54 sites showing fabrics of para-and ferro-magnetic origin. Most fabrics can be interpreted to have a magmatic origin, according to the scarcity of solid-state deformation in most part of the massif. Magnetic foliations are shallowly dipping in the granite laccolith and contain a sub-horizontal ENE-WSW lineation. The gabbro-syenite body displays concentric magnetic foliations having variable dips and steeply-plunging lineations. The SIC can be interpreted to be intruded along an NNW-SSE, 200 km-long fault, perpendicular to the magnetic lineation within the laccolith, and was preceded by the intrusion of basic sills and plugs. The SIC intruded the Mesozoic series of the Lusitanian Basin during the post-rift, passive margin stage, and its geometry was only slightly modified during the Paleogene inversion that resulted in thrusting of the northern border of the intrusion over the country rocks.