Jurassic sedimentary record and tectonic evolution of the northwestern corner of Africa

The history of the opening seaway from the westernmost Tethys to the Central Atlantic is traced by the analysis of the sedimentary facies development in the external Rif basin of Northern Morocco and the geological and seismic data from the Moroccan Atlantic continental margin. In the Rif basin, after the early Sinemurian, sedimentary facies dated by ammonites, foraminifers and brachiopods, indicate a progression of rapid subsidence resulting from extensional tectonic (tilted blocks, escarpment fault breccias, neptunian dykes etc.) from the N and NE to the S and SW. From the Toarcian to the Bajocian, deltas progress from the W and SW into the `'Rides sud-rifaines'' realm. From the late Bathonian to the Oxfordian, deep-sea fans develop in the external Rif. During the same period, deltaic sediments fill in the Middle Atlas basin of Eastern Morocco and progress into the external Rif. The top of the Jurassic is characterised by carbonate deposits. At the northwestern corner of Africa, the subsidence of the sedimentary basins by rifting is initiated in the late Triassic; however, at the Mazagan transect of the Atlantic continental margin, the tectonic pattern characteristic of a passive continental margin appears clearly only in the early Jurassic. At the foot of the Mazagan escarpment, the sedimentary record shows a foundering of the first bloc during early to middle Lias. A thermal uplift phase is indicated by emersion of the African margin shoulder in late Liassic, and thermal relaxation starts in the middle Jurassic. The morphology of this transect, compared with the conjugate side of the American continent is most easily explained by the uniform sense simple shear model.

Artrodesis de tobillo: resultados comparativos de diferentes técnicas

INTRODUCTION: Ankle arthrodesis in an intervention that may be performed using a variety of surgical approaches. The joint may be stabilized using diferent systems, with or without bone graft. MATERIAL AND METHODS: Retrospective study that collected the results of 40 patients who underwent ankle arthrodesis; the complications that arose were analyzed, results according to the AOFAS clinical rating system, global patient satisfaction and the relationship with the articular approach route, the !xation system or the usage of grafts.RESULTS: 55% of the patients presented one or more complication that motivated a total of 12 re-interventions in 10 patients (excludes removal of osteosynthesis material). The absence of consolidation, which required a new arthrodesis was more frequent in patients where osteosynthesis was not used (two out of three cases) than in those using screws (four out of 24 cases), while there was no register of this in 13 patients in which intramedullary pin. The use of the distal extreme of the fibula or the iliac crest as bone graft has failed to improve the consolidation. Arthroscopic approaches avoid the appearance of soft tissue complications, although the consolidation disorders were more frequent. The average score on the AOFAS clinical rating system was 56.4±21.2 and 55% of the patients were satisfied. CONCLUSIONS: Although the case histories fail to provide significant results, it is a demanding intervention, with an elevated complication rate. Intramedullary pins seem to favor improved consolidation.