Contribuição para a datação do conglomerado de Odeáxere

According to P. Choffat, Odeáxere conglomerate was Oxfordian in age, and would represent the unconformity between Malm and Dogger. Choffat's opinion was based exclusively in a lithological comparison with conglomerates from Arrábida; these conglomerates are now reported to the Dogger, as they are intercalated between beds with Timidonella sarda. However, in the mesogean realm, the stratigraphical position of T. sarda in the Dogger is still not accurately known. Some authors think its range would extend from Aalenian until the Bajocian, yet others think it would be more restricted, from Aalenian to the lower Bajocian only. Its stratigraphical span seems to be even more restricted in Algarve: uppermost Aalenian to lowermost Bajocian

Goldra: premier gisement karstique en Algarve, faune et industries

A bone breccia from Goldra, near Loulé, is studied. It corresponds to the infilling of a karst depression, consisting of: rather worn and probably transported dolomite pebbles at the bottom; accumulations of frequently burnt bone scraps, much broken and with acute edges (no transport), certainly debris of human food, suggesting habitat level (s); in association with the former, stone (flint, quartz, quartzite, graywacke) rather uncharacteristic artifacts that seem compatible with middle and upper Paleolithic, or with Epipaleolithic; and small mammal teeth and bones. Fauna includes an extinct species, Microtus brecciensis recognized for the first time in Portugal. It is not older than Riss-Wiirm interglacial, and may be of this age or later, maybe that of one of wurm's first interstades. Fauna points out to a varied landscape with open country and woods; and to a rather warm and dry temperate, or dry subtropical mediterranean climate. Climate differences should not be significant in comparison with the extant situation. The presence of the mammal species found so far is consistent with modern distribution

Aspectos gerais da tectónica alpina no Algarve

The study of the tectonic strutures affecting the mesozoic and cenozoic deposits of Algarve's basin allows us to recognize the following phases of the Alpine orogeny: Jurassic (Upper Triassic at least)-Lower Cretaceous N-S distension; N-S compression during the setting-up of the Monchique syenite dome at the uppermost Cretaceous; Paleogene compression (?) (only locally? - at the Albufeira salt dome); Lower Miocene N-S distension; Upper Burdigalian to Lower Langhian N-S and E-W distension; N-S or NNW-SSE compression after the Middle Miocene; E-W compression after the Upper Tortonian; N-S compression during the Quaternary. NE-SW fractures affecting the Paleozoic basement are related with the first distension phases. The mesozoic N-S distension are the main cause of the two E-W flexures so far recognized. A tectonic inversion event did occur after the setting up of the Monchique syenite. If, the Lower Cretaceous Lower Miocene Albufeira's unconformity, is a local effect of halokinesis then, the true tectonic inversion of the Algarve basin, did occur in the Middle Miocene. These events correlate well with those knewn at Southern Spain and Morocco

Estratigrafia do Caloviano do Algarve oriental

The comparative study of the Callovian sections in eastern Algarve allowed us to demonstrate that the discontinuity surface at the base of Malm lies always over the Lower-Callovian, as opposite to what happens in western Algarve; the Bathonian-Callovian transition, continuous in western Algarve (Mareta beach) is marked, in eastern Algarve, by a generalised discontinuity of variable vertical extention. It is verified that, in eastern Algarve, the Callovian formations are always or at the nucleus of anticlinal structures, probably linked to halokinetic tectonic activity, or in large radins folds derived from compressive phases

Diachronous evolution of Late Jurassic-Cretaceous continental rifting in the northeast Atlantic (west Iberian margin)

Regional (2-D) seismic reflection profiles, outcrop, and borehole data are used to characterize the evolution of deep offshore sedimentary basins in southwest Iberia (Alentejo Basin). The interpreted data indicate the bulk of Late Jurassic–earliest Cretaceous subsidence occurred in the present-day continental slope area, as shown by (1) significant thickening of synrift strata basinward from a slope-bounding fault system (SFS), west of which the total thickness of sediment can reach more than 9.0 km, and (2) relatively thin Mesozoic strata east of the SFS, where thickening of synrift units against principal faults is limited. Five principal regressive events and their basal unconformities reflect tectonic uplift and relative emersion in proximal basins, which were located on the rift shoulder to subsiding tilt blocks west of the SFS. These regressive events are correlated with major rift-related events occurring on the deeper margin. Direct comparisons with the Peniche Basin of northwest Iberia reveal that significant portions of the Iberian lower plate margin were uplifted and eroded during the last stages of continental rifting. This process was repeated at different times (and in different areas) as the locus of rifting and continental breakup migrated northward. As a result, two distinct rift axes are recognized in west Iberia, a first axis extending from the Porto Basin to the Alentejo Basin and a second axis located on the outer proximal margin north of 38°30N. In addition, the SFS delimited (1) prograding deposits of Cretaceous-Paleogene age and (2) late Cenozoic deposits draping the modern continental slope. These latter facts demonstrate that on lower plate passive margins, the relative position of the continental slope is established during the final rifting episode(s) preceding continental breakup