Magnetostratigraphic, biostratigraphic, and stable isotope stratigraphy of an Upper Miocene drill core from the Salé Briqueterie (northwestern Morocco):...

We report a high-resolution stable isotope, carbonate, magnetostratigraphic, and biostratigraphic record from a 175-m drill core from the Salé Briqueterie, which is part of the Bou Regreg section in northwestern Morocco. The Salé drill core spans the interval from paleomagnetic Chron C4n partim to C3r (earliest Gilbert), which represents the time leading up to and including the isolation and desiccation of the Mediterranean (i.e., the Messinian salinity crisis). During Chrons C3An and C3Ar (6.935 to 5.894 Ma) the isotope and carbonate signals display quasi-periodic variations with estimated periods of 40 and 100 kyr, respectively. We interpret the 40-kyr δ^18O variations as reflecting changes in global ice volume caused by obliquity-induced changes (41 kyr) in solar insolation in polar regions. The 100-kyr carbonate variations probably represent long-term modulation of the amplitude of the precessional cycle (~21 kyr), which is not resolved by our sampling frequency. The cyclic nature of the oxygen isotope signal permits us to extend the isotope nomenclature of Shackleton et al. (1994a) from stage TG24 in Chron C3r (earliest Gilbert) to stage C3Ar.δ^18O.18 at the base of Chron C3Ar (6.935 Ma). A major change in paleoceanographic conditions is recorded across the Tortonian/Messinian boundary, which we correlate to Chron C3Bn at 7.04 Ma. Benthic foraminiferal δ^18O values increased by an average of 0.4‰ in two steps at 7.17 Ma and 6.8 Ma and δ^13C values decreased by 0.7-0.8‰ between 7.1 and 6.8 Ma, representing the late Miocene carbon shift. The first step in δ^18O values coincides with an inferred reversal in deep water circulation through the Rifian Corridor, and the second correlates with the base of the Tripoli Formation and onset of "crisis conditions" in the Mediterranean. We suggest that the increase in δ^18O values represents, at least in part, an increase in global ice volume that lowered sea level and contributed to the establishment of a negative water budget in the Mediterranean. Average δ^18O values remained high throughout most of Chrons C3Ar and C3An, reaching maximum δ^18O values during isotope stages TG20 and 22 in Chron C3r (earliest Gilbert). The glacio-eustatic falls associated with these events may have resulted in the complete isolation of the Mediterranean from the world ocean (Shackleton et al., 1994a). Following stage TG12 in the Salé record, there exists a trend toward progressively lower δ^18O values that may represent a series of marine transgressions that eventually reflooded the Mediterranean and ended the Salinity Crisis

Adaptation du mode opératoire pour la réalisation d’essais en compression « vraie » sur les roches

Sur la base d’une étude approfondie de la littérature et d’un programme d’essais sur le grès de Fontainebleau, les artefacts expérimentaux rencontrés dans la réalisation des essais de compression triaxiale sont analysés. En particulier, on montre que le frettage à l’interface de l’éprouvette et des plateaux de chargement modifie l’allure des courbes contrainte-déformation, affecte le mode de rupture ainsi que les caractéristiques des bandes de cisaillement (orientation, épaisseur). Un protocole d’essais visant à supprimer ces artefacts est proposé et validé. Celui-ci consiste en une lubrification efficace de l’interface associée à la mise en place d’une protection imperméabilisante permettant d’éviter la pénétration du lubrifiant dans la roche

Turbidity and Chemical Oxygen Demand Reduction from Pig Slurry through a Coagulation Flocculation Process

Pig slurry is considered a high-risk effluent that causes several environmental problems if it is not adequately managed and treated. White Iberian pig farms in the southeast of Spain treat their slurry in situ using separation, double filtration, decantation, and constructed wetland treatments. However, the pretreatment process does not successfully reduce solids, which leads to clogging in the constructed wetlands (CWs). The main objective of this research paper is to reduce the turbidity and chemical oxygen demand (COD) from the effluent to make it appropriate for CW treatment. Optimization of the coagulation–flocculation (CF) process using iron chloride and a cationic flocculent DKFLOCC-1598 was investigated by a central composite design method (CCD). The effects of coagulant concentration, pH, and flocculent on the COD and turbidity removal were evaluated. The best results were found using 0.024 mol L−1 iron chloride and 0.164 mL L−1 flocculent at pH 7.5, which reduced COD by 96% and delivered turbidity removal of 97%. Therefore, the results indicate the high efficiency of the treatment method in reducing the COD and suspended solids

The value of the Bou Regreg section as a boundary stratotype of the pliocene

Benson Richard H., El Bied Rakic K., Bonaduce G., Berggren William A., Aubry Marie-Pierre, Napoleone G., Hodell D. The value of the Bou Regreg section as a boundary stratotype of the pliocene. In: Géologie Méditerranéenne. Tome 14, numéro 1, 1987. Xe colloque africain de micropaléontologie. A – Le Cenozoique. Rabat – Université Mohamed V – Maroc. 29 septembre-1er octobre 1987. p. 83

The value of the Bou Regreg section as a boundary stratotype of the pliocene

Benson Richard H., El Bied Rakic K., Bonaduce G., Berggren William A., Aubry Marie-Pierre, Napoleone G., Hodell D. The value of the Bou Regreg section as a boundary stratotype of the pliocene. In: Géologie Méditerranéenne. Tome 14, numéro 1, 1987. Xe colloque africain de micropaléontologie. A – Le Cenozoique. Rabat – Université Mohamed V – Maroc. 29 septembre-1er octobre 1987. p. 83