Structure and evolution of the Neogene Guercif Basin at the junction of the Middle Atlas Mountains and the Rif thrust belt

Copyright 2000, AAPG. See also: http://www.aapg.org/bulletin/index.cfm; http://atlas.geo.cornell.edu/morocco/publications/gomez2000AAPG.htmThe Guercif basin of northern Morocco occupies a 50 x 60 km area where the transpressional Middle Atlas mountains terminate and abut the Rif thrust belt. Analysis of over 800 km of 2-D (two-dimensional) seismic reflection profiles and eight exploratory wells, in combination with existing geological data, suggests a late Miocene episode of extension (4%, or 1.7 km, maximum) and a subsequent episode of contraction since the end of the Miocene. Most of the late Miocene deposition was concentrated in a narrow graben (herein referred to as the Guercif graben), which contrasts with the wider physiographic expression of the basin today. Geohistory analysis indicates that tectonic subsidence persisted until the Messinian, and sediment loading continued to drive subsidence even after extension stopped. Timing constraints demonstrate the contemporaneity of the Guercif graben and west-southwest-vergent thrust tectonics of the Rif thrust belt. Similar timing and proximity with the Rif, as well as the graben geometry, suggest that extension in the Guercif basin, in addition to other smaller extensional basins in the northern Middle Atlas region adjacent to the Rif, may represent the distal effects of a broad lateral shear zone bounding the thrust belt. The Neogene Guercif basin is superimposed on the Mesozoic Middle Atlas rift, which experienced basin inversion during the Cenozoic, and seismic reflection interpretations in the southern Guercif basin depict old Mesozoic rift faults reactivated as reverse faults. Unconformities illustrate that the uplift of the Middle Atlas appears to be primarily a late Cenozoic phenomenon. The Guercif basin offers a special opportunity for petroleum exploration within an aborted rift basin such as the Middle Atlas. Mesozoic source rocks in the Middle Atlas may have been sufficiently buried beneath Neogene basin sediments to reach maturity, and the late Cenozoic timing of contraction can produce suitable structural traps

Inversion of synrift normal faults in the High Atlas Mountains, Morocco

Copyright 1997, Society for Exploration Geophysics. See also: http://segdl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=LEEDFF000016000008001171000001&idtype=cvips&gifs=Yes; http://atlas.geo.cornell.edu/morocco/publications/beauchamp1997.htmStructural inversion related to intracontinental rifting occurs when extensional rift faults reverse their sense of motion during subsequent episodes of compressional tectonics. Features generated by extension, such as half grabens, are uplifted to form positive anticlinal structures

Crude incidence in two-phase designs in the presence of competing risks.

BackgroundIn many studies, some information might not be available for the whole cohort, some covariates, or even the outcome, might be ascertained in selected subsamples. These studies are part of a broad category termed two-phase studies. Common examples include the nested case-control and the case-cohort designs. For two-phase studies, appropriate weighted survival estimates have been derived; however, no estimator of cumulative incidence accounting for competing events has been proposed. This is relevant in the presence of multiple types of events, where estimation of event type specific quantities are needed for evaluating outcome.MethodsWe develop a non parametric estimator of the cumulative incidence function of events accounting for possible competing events. It handles a general sampling design by weights derived from the sampling probabilities. The variance is derived from the influence function of the subdistribution hazard.ResultsThe proposed method shows good performance in simulations. It is applied to estimate the crude incidence of relapse in childhood acute lymphoblastic leukemia in groups defined by a genotype not available for everyone in a cohort of nearly 2000 patients, where death due to toxicity acted as a competing event. In a second example the aim was to estimate engagement in care of a cohort of HIV patients in resource limited setting, where for some patients the outcome itself was missing due to lost to follow-up. A sampling based approach was used to identify outcome in a subsample of lost patients and to obtain a valid estimate of connection to care.ConclusionsA valid estimator for cumulative incidence of events accounting for competing risks under a general sampling design from an infinite target population is derived

Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.This study was carried out under a MNT ERA-Net Project named NANOMED. The authors gratefully thank the Midi-Pyrénées region (MNT ERA Net Midi-Pyrénées Région, NANOMED2 project) and the Institute National Polytechnique de Toulouse (BQR INPT 2011, BIOREVE project) for supporting this research work, especially the financial support for research carried out in the CIRIMAT and the LGP laboratories (France), and the Basque government and Tratamientos Superficiales Iontech, S.A. for their financial and technical support under the IG-2007/0000381 grant for the development of the LEPS device and deposition of the coatings carried out in Inasmet-Tecnalia. The French industrial collaborators (TEKNIMED SA and 2PS SA) were financed by the OSEO programs

Synthesis and Antibacterial Study of New Microporous Zinc Phosphate Bioceramics

In a ternary system composed of aluminum phosphate, zinc oxide, and orthophosphoric acid, we have prepared microporous ceramics for orthopedic and dental uses. Firstly, we have prepared the ceramics with uncontrollable porosity by sintering blocs of the zinc phosphate cement drawn from the ternary system. Then, based on a binary system consisted of aluminum phosphate, zinc oxide, and some porogenic additives, we have prepared ceramics with good and homogeneous porosity structure. In the second issue, the preparation is made by a simple mixture of powders. Thus, after homogenization, compaction and sintering at high temperatures, the resulted ceramics developed high mechanical resistances. Besides, antibacterial tests on the ceramics have been conducted and shown good biological performances. The mechanical behavior as well as the biological properties candidate the ceramics to be a good alternative to the hard tissue. Eventually, all preparations are controlled and investigated using several technics such as FTIR, XRD, SEM, TAG-TAD, mechanical test, and an antibacterial activity test

Intracontinental rifting and inversion: Missour Basin and Atlas Mountains, Morocco

An edited version of this paper was published by the American Association of Petroleum Geologists (AAPG). Copyright 1996, AAPG. See also: http://www.aapg.org/bulletin/index.cfm; http://atlas.geo.cornell.edu/morocco/publications/beauchamp1996.htmThe intracontinental High and Middle Atlas mountain belts in Morocco intersect to form the southern and western margins of the Missour Basin, an intermontane basin formed as a result of the uplift and inversion of the Mesozoic Atlas paleorifts. These rifts were areas where the crust was greatly attenuated and more subject to deformation in response to nearby plate boundary tectonics. Data from observations based on seismic reflection profiles and wells over the Missour basin for hydrocarbon exploration and field mapping were used to understand the basin evolution, structural styles, and inversion timing of the nearby Atlas Mountains. Hercynian and Mesozoic normal faults were reactivated into high-angle reverse and thrust faults in the Mesozoic during the Jurassic, early Cretaceous (early Alpine phase), and the Paleogene (late Alpine phase). The reactivation of synrift normal faults of the paleo-Atlas rifts inverted previous half grabens into anticlinal structures, with the axis of the half graben centered below the axis of the inverted anticline. The resulting inverted fold geometries are controlled by the geometries of the extensional planar or listric faults

Étude expérimentale de la bio-accumulation des lanthanides chez la moule Mytilus galloprovincialis (Lamarck) du littoral méditerranéen marocain

La microscopie ionique et la microanalyse X ont été utilisées pour détecter in situ, sur coupes histologiques, les éléments bio-accumulés dans la moule Mytilus galloprovincialis, contaminée expérimentalement in vitro par le cérium, le thulium et le lanthane. Les éléments absorbés, sous forme soluble à l’état de traces dans les organites cibles (les lysosomes), sont concentrés sous forme de précipités de phosphate insolubles dans les cellules épithéliales des branchies, des glandes digestives et des palpes labiaux

An integrated geophysical investigation of recent seismicity in the Al-Hoceima region of North Morocco

Copyright 1997, SSA. See also: http://www.seismosoc.org/publications/bssa-toc.html; http://atlas.geo.cornell.edu/morocco/publications/calvert1997.htmData produced by the Moroccan national seismological network and marine seismic reflection profiles are used to investigate the most seismically active region in Morocco, located on the Mediterranean coast at the intersection of the Rif mountain belt and the submarine Alboran Ridge. This region, in the vicinity of the city of Al-Hoceima, marks an east-west transition in the marine and land deformation styles of the distributed plate boundary between Africa and Iberia, and was the site of a Mw=6.0 earthquake on May 26, 1994. The epicenter of the Al-Hoceima earthquake is relocated onshore, refining the initial submarine location close to the Alboran Ridge. The spatial distribution of foreshocks and aftershocks shows a NE-SW trend that continues partly offshore and is subparallel to the earlier, yet still prominent, Miocene geologic structural trend. The predominantly strike-slip focal mechanism for the Al-Hoceima event is characteristic of earthquakes in the region. Marine seismic reflection profiles, that intersect the offshore region of seismicity, image active high angle faults with possible strike-slip components. The seismicity trend is not directly related to the submarine Alboran Ridge or the geomorphologically prominent Nekor fault. Deformation appears to be occurring on a number of subsidiary strike-slip faults that together compose a NE-SW zone of distributed shear. The distributed strike-slip and documented normal faulting taking place in the eastern Rif mountains, although characteristic of the Rif region, are in contrast to the thrusting style of deformation that occurs farther to the east in the Algerian Tell Atlas. This may be related to the reported lateral variations and evolution of the convergent plate boundary in these regions during the Neogene and Quaternary times

Bio-accumulation des métaux lourds chez l'oursin Paracentrotus lividus (Lamarck) sur la côte Est de la Méditerranée marocaine

La composition minérale de l’oursin (Paracentrotus lividus), échinoderme benthique fréquent dans la côte Est de la Méditerranée marocaine, concorde avec celle de l’eau du site de prélèvement. En outre, la comparaison des valeurs obtenues sur des oursins récoltés en automne avec celles élevées qui sont obtenues sur des oursins récoltés au printemps suppose l’existence d’un cycle métabolique saisonnier. Les teneurs observées dans l’épithélium digestif et dans les gonades laissent présager les possibilités d’échanges métaboliques entre les systèmes digestif et reproducteur. Ce phénomène est non étudié jusqu’à présent chez les Échinides. Les lysosomes sont les organites cibles où la plupart des éléments, absorbés à l’état de traces sous forme soluble, se concentrent sous forme de précipités de phosphates insolubles

Inversion tectonics and the evolution of the High Atlas Mountains, Morocco, based on a geological-geophysical transect

An edited version of this paper was published by the American Geophysical Union (AGU). Copyright 1998, AGU. See also: http://www.agu.org/pubs/crossref/1999/1998TC900015.shtml; http://atlas.geo.cornell.edu/morocco/publications/beauchamp1999.htmThe High Atlas Mountains of North Africa were formed over a major intracontinental rift system that had extended from what is now the Atlantic margin of Morocco to the Mediterranean coast of Tunisia. The Atlas rift system began in the Triassic and was active through the Jurassic. The inversion phase of the Atlas rift system began in the Early Cretaceous and extended into the present. The major uplift phase occurred between 30 and 20 Ma (Oligocene-Miocene) and corresponds to the Alpine orogenic event. The uplift and inversion of the Atlas rift system resulted in a shortening of the rift basin by a minimum of 36 km. A restoration of the deformed cross section indicates the original Atlas rift basin was approximately 113 km wide, comparable to the width of the present-day Red Sea. Synrift and postrift sedimentary rocks were uplifted by the reactivation of synrift normal faults, with further shortening along newly formed thin-skinned thrust faults. Structures formed by the reactivation of synrift faults resulted in structures with different geometries than those created by newly formed fault-bend and fault-propagation faults. Shortening across the High Atlas Mountains involved a partitioning of strain, with the greatest magnitude of shortening occurring along the margins of the High Atlas Mountains