No abstract

More than one century after its original description by Marsh in 1877, we report in this paper the first uncontroversial evidence of a member of the genus Stegosaurus out of North America. The specimen consists of a partial skeleton from the Upper Jurassic of Portugal, herein considered as Stegosaurus cf. ungulatus. The presence of this plated dinosaur in the upper Kimmeridgian-lower Tithonian Portuguese record and synchronic levels of the Morrison Formation of North America reinforces previous hypothesis of a close relationship between these two areas during the Late Jurassic. This relationship is also supported by geotectonic evidences indicating high probability of an episodic corridor between the Newfoundland and Iberian landmasses. Together, Portuguese Stegosaurus discovery and geotectonic inferences could provide a scenario with episodical faunal contact among North Atlantic landmasses during the uppermost Kimmeridgian-lowermost Tithonian (ca. 148-153 Ma ago).

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.

No abstract

The Arrábida chain is an impressive basin inversion structure of Miocene age that is exposed over almost the entire Mesozoic sedimentary sequence of the southern sector of the Lusitanian Basin (LB). This field trip provides a complete cross-section through some of the key outcrops, illustrating important moments in the tectono-stratigraphic evolution of an Atlantic-type basin, namely: a) the extensional tectonic control on Early-Middle Jurassic sedimentation in a low-to high-energy carbonate ramp setting; b) the presence of a basin-wide unconformity at the Middle-Upper Jurassic transition; c) the tectonic rejuvenation of the eastern border of the LB, the effects of rift shouldering, and the progressive exhumation of the eastern margin in the sedimentary infill; d) the distal expression of the basin's breakup unconformity (rift to drift stage); and e) magmatism in a passive margin.Keywords: Atlantic-type basin, tectono-stratigraphic evolution, Lusitanian Basin, Arrábida ResumoA cadeia da Arrábida é uma impressionante estrutura de inversão de bacia, formada no Miocéni-co, que expôs à superfície quase toda a sequência sedimentar mesozóica do sector sul da Bacia Lusitaniana (BL). Esta excursão permite a realização de um perfil estratigráfico quase integral através de alguns dos principais afloramentos que ilustram momentos importantes da evolução tectono-sedimentar desta bacia de tipo atlântico, a saber: a) o controle tectónico de natureza distensiva durante a sedimentação no Jurássico Inferior / Médio, numa plataforma carbonatada de baixa a alta energia; b) uma significativa discordância bacinal na transição Jurássico Médio / Superior; c) o rejuvenescimento tectónico do bordo oriental da BL, com o consequente efeito no enchimento sedimentar proximal induzido pelo levantamento (rift shouldering) e exumação progressiva deste relevo marginal; d) a expressão distal da interrupção da subsidência na bacia (basin's breakup unconformity) assinalando o fim das fases de rifting e e) evidências de actividade magmática numa margem passiva.Palavras-chave: bacia de tipo atlântico, evolução tectonostratigráfica, Bacia Lusitaniana, Arrábida