The Jurassic–Cretaceous depositional and tectonic evolution of the southernwestern margin of the Neotethys Ocean, Northern Oman and United Arab Emirates

The concept that the autochthonous, parautochthonous and allochthonous Permian–Cretaceous sequences in the United Arab Emirates (UAE) and Oman record the transition from platform, slope to basin sedimentation within the southern part of Neotethys has been fundamental to the interpretation of the geological history of the region. The results of a major geological mapping programme of the UAE, carried out by the British Geological Survey for the Federal Government of the UAE, coupled with the detailed examination of key sections within northern Oman has led to a re-evaluation of the geological evolution of this region. This detailed study has led to a greater appreciation of the sedimentology and depositional setting of the sediments laid down along the northeastern Arabian continental margin during the Jurassic to Cretaceous, allowing a more refined model of Neotethys Ocean basin evolution to be established. The model charts the progressive breakup of the Arabian continental margin and closure of Neotethys during the mid to late Cretaceous and is divided into three main stages: Stage 1—Initial rifting and formation of the Neotethys Ocean, followed by a prolonged period of stable, passive margin sedimentation which extended from the Permian to Late Jurassic times; Stage 2—Uplift and erosion of the shelf margin during the Late Jurassic to Early Cretaceous, coincident with increased carbonate-clastic sedimentation in the outer ramp, distal slope and basinal areas; Stage 3—Increased instability during the Late Cretaceous leading to the breakup of the platform margin and foreland basin sedimentation accompanying the obduction of the Oman-UAE ophiolite. Data obtained for the upper part of the platform and platform margin to slope successions has revealed that the topography of the “shelf”-slope-basinal margin was more subdued than previously thought, with this more gentle ramp margin morphology persisting until early to mid-Cretaceous times when the platform margin started to become unstable during ophiolite obduction. The thrust-repeated allochthonous sedimentary rocks of the Hamrat Duru Group were deposited on the outer platform margin/lower slope rise to basinal plain of this basin margin and includes the dismembered remains of two turbidite fan systems which fed carbonate-rich detritus into deeper parts of the ocean. A re-evaluation of the chert-rich sequences, previously equated with deposition on the abyssal plain of Neotethys, has led to the conclusion that they may record sedimentation at a much shallower level within a starved ocean basin, possibly in a mid-ramp (above storm wave base) to outer ramp setting. A marked change in basin dynamics occurred during the mid-Cretaceous leading to the development of a shallow ramp basin margin in Oman with terrestrial to shallow marine sedimentary rocks interdigitating with red siliceous mudstones. By contrast, the contemporaneous succession in the Dibba Zone of the UAE indicates considerable instability on a steep shelf break. This instability is recorded by the presence of several major olistostrome deposits within the Aruma Group of the UAE which are thought to have been generated in advance of the rapidly obducting Oman-UAE ophiolite

Le rôle de la structuration dans la rétention verbale

Summary Three groups (A, B and C) consisting of twelve subjects each learned a list of twenty words, after which they were given a free recall test. Jmmediatly following acquisition a disorganized learning trial was given to group A and an organized learning trial to group C ; subjects in group B were given no learning trial of any sort. Fifteen days later subjects were given ten consecutive free recall trials (without being shown the stimuli). Recall was greater for subjects in group C than for subjects in group B. However, only half the subjects in group A recalled less than subjects in group B. These results were interpretee in terms of transitory dominances existing within the verbal repertory which determine learning and permanent dominances which determine long-term retention.Résumé On a réalisé une expérience d'apprentissage d'une liste de 20 mots en situation de rappel libre avec trois groupes (A, B, C) de 12 sujets chacun. Immédiatement après la phase d'acquisition, identique pour les trois groupes, les sujets du groupe A ont subi une épreuve de déstructuration, les sujets du groupe C une épreuve de renforcement de la structuration, alors que les sujets du groupe B restaient inactifs. Quinze jours plus tard, les trois groupes ont effectué 10 essais consécutifs d'évocation sans nouvelles présentations des stimulus. Il a été montré, conformément à l'hypothèse, que l'épreuve d'évocation était mieux réussie par les sujets du groupe C que par ceux du groupe B. Par contre, dans le cas du groupe A, dont on supposait qu'il serait inférieur au groupe B, la moitié des sujets seulement, dont la structuration est la plus faible au terme de l'apprentissage, réussit moins bien l'épreuve d'évocation que les sujets correspondants du groupe B. L'interprétation de ces résultats fait appel à deux concepts : les dominances transitoires à l'intérieur du répertoire verbal qui déterminent principalement l'apprentissage et les dominances permanentes qui déterminent la rétention à long terme.Ehrlich Stéphane, Ricateau M. Le rôle de la structuration dans la rétention verbale. In: L'année psychologique. 1970 vol. 70, n°1. pp. 95-108

Psychologie clinique et pédagogie

Ricateau M., Doron R., Cocude M., Hugonot R. Psychologie clinique et pédagogie. In: L'année psychologique. 1985 vol. 85, n°4. pp. 613-620

Psychologie clinique et pédagogie

Ricateau M., Doron R., Cocude M., Hugonot R. Psychologie clinique et pédagogie. In: L'année psychologique. 1985 vol. 85, n°4. pp. 613-620