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11.
Hassane El Mkami Henrik Friis Adrian A. Finch G. M. Smith 《Physics and Chemistry of Minerals》2010,37(8):519-528
The location and coordination of Mn2+ paramagnetic luminescent centres in three natural samples of leucophanite (ideally, NaCaBeSi2O6F) have been investigated by electron paramagnetic resonance (EPR) and electron spin-echo envelope modulation (ESEEM) spectroscopy.
Continuous wave (cw)-EPR was carried out at multiple frequencies (9, 94 and 188 GHz) which allowed the precise determination
of the spin Hamiltonian parameters. The simulation of the cw-EPR spectra shows that the signal originates from one manganese
located in a single distorted site. This distortion was close to axial symmetry with a slight rhombicity and was consistent
with an eight coordinated Mn2+ substituting for Ca2+. Spectral differences between the samples could be attributed mainly to D-strain effect. Three-pulse ESEEM spectroscopy was
also used to investigate the coordination environment of the manganese and showed weak coupling between the manganese and
beryllium (9Be), sodium (23Na) and fluorine (19F) nuclei in the second and subsequent coordination spheres. The Mn ligand distances estimated from the ESEEM data are in
good agreement with bond distances estimated from X-ray diffraction data. To our best knowledge, only few ESEEM studies have
been reported so far in Earth science and this is believed to be the first detailed ESEEM study of Mn2+ in a natural mineral system. 相似文献
12.
El Hassane El Arabi José Bienvenido Diez Jean Broutin Rachid Essamoud 《Comptes Rendus Geoscience》2006,338(9):641-649
The Middle Anisian has been palynologically characterized for the first time, at the whole Moroccan scale, in the High Atlas of Marrakech. The stratigraphic, tectonic and paleogeographic implications of this discovery are analysed. To cite this article: E.H. El Arabi et al., C. R. Geoscience 338 (2006). 相似文献
13.
Abdelilah Fekkak André Pouclet Hassane Ouguir Hassane Ouazzani Lakhlifi Badra Dominique Gasquet 《Geodinamica Acta》2013,26(6):373-385
Abstract The Early Cryogenian groups of Sidi Flah, Kelaat Mgouna and Boumalne (Saghro, Anti-Atlas, Morocco) are constituted by turbiditic deposits and interbedded lavas, accumulated in tectonic basins. At Sidi Flah, volcanics are transitional showing initial rift tholeiites (IRT) fingerprint and alkali basalts of oceanic island basalt (OIB) compositions. At Kelaat Mgouna, volcanics consist of low-Nb continental tholeiites. At Boumalne, basalts are of IRT composition. The volcanic and sedimentary formations belong to a nascent rift caused by thermal doming along a SW-NE axis, the Saghro rift. The continental break-up occurred in the early Neopro- terozoic and during the Rodinia supercontinent dislocation, within a continent called “Ibero-saharian Craton” which was in front of the West-African Craton located near the South Pole. The Saghro rift is contemporaneous to the opening of an oceanic domain represented by Central Anti-Atlas ophiolites and related to the extension of the Brazialiano Ocean. © 2001 Éditions scientifiques et médicales Elsevier SAS 相似文献
14.
Thomas Lehmann Patrick Vignaud Hassane Taïsso Mackaye Michel Brunet 《Journal of African Earth Sciences》2004,40(5):201
The Mission Paléoanthropologique Franco-Tchadienne (MPFT) found a new species of Orycteropodidae (Mammalia, Tubulidentata) in the Kollé fossiliferous sector, northern Chad. After Orycteropus abundulafus [Journal of Vertebrate Paleontology 20 (1) (2000) 205–209; Lehmann, T., Vignaud, P., Likius A., Brunet M., in press. A new Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of Northern Chad. Zool. J. Linnean Soc.], this specimen is the second complete skeleton of fossil aardvark found in the Djurab desert. It is the first complete representative of an Orycteropus species found in the Pliocene of Africa. In regard to the Miocene fossil aardvarks, this new taxon, Orycteropus djourabensis nov. sp., shows more affinities with the extant O. afer. The main differences are the larger teeth and the shorter hand in the fossil form. Kossom Bougoudi and Kollé represent a chronological series that gives a unique opportunity for studying the evolution of the African Tubulidentata around the Mio-Pliocene boundary (5.5-4 My). The new species is distinct from the older Chadian Orycteropodid from KB and it embodies the taxonomic turnover that took place within the order Tubulidentata around this boundary in Africa. Moreover, this new species is the oldest known Orycteropus species that clearly belongs to the modern forms including the extant aardvark. 相似文献
15.
Lionel Hautier Hassane Taisso Mackaye Fabrice Lihoreau Pascal Tassy Patrick Vignaud Michel Brunet 《Journal of African Earth Sciences》2009,53(4-5):171-176
New fossil remains of the proboscidean genus Anancus are described. Among them, a complete skull allows us to revisit for the first time the entire Chadian Anancus fossil record. This genus occurred in the Old World from the late Miocene up to the early Pleistocene. The analysis of dental and cranial characters was allowed individual variations from specific characters to be distinguished. In this study we show that Anancus kenyensis and Anancus osiris are very likely synonym taxa which leads us to emend the diagnosis of A. kenyensis. In addition, this study shows that dental characters in anancines lineage are of little significance for biostratigraphical inference, by contrast to previous works. This study brings new data about the phylogenetical and palaeobiogeographical history of the African anancines. 相似文献
16.
Hassane Rahali 《国际地球制图》2019,34(1):43-77
This paper aims at providing an answer as to whether generalization obtained with data-driven modelling can be used to gauge the plausibility of the physically based (PB) model’s prediction. Two statistical models namely; Weight of Evidence (WofE) and Logistic Regression (LR), and a PB model using the infinite slope assumptions were evaluated and compared with respect to their abilities to predict susceptible areas to shallow landslides at the 1:10.000 urban scale. Threshold-dependent performance metrics showed that the three methods produced statistically comparable results in terms of success and prediction rates. However, with the Area Under the receiver operator Curve (AUC), statistical models are more accurate (88.7 and 84.6% for LR and WofE, respectively) than the PB model (only 69.8%). Nevertheless, in such data-sparse situation, the usual approaches for validation, i.e. comparing observed with predicted data, are insufficient, formal uncertainty analysis (UA) is a means for evaluating the validity and reliability of the model. We then refitted the PB model using a stochastic modification of the infinite slope stability model input scheme using Monte Carlo (MC) method backed with sensitivity analysis (SA). For statistical models, we used an informal Student t-test for estimating the certainty of the predicted probability (PP) at each location. Both modelling outputs independently show a high validity; and whereas the level of confidence in LR and WofE models remained the same after performance re-evaluation, the accuracy of the PB model showed an improvement (AUC = 72%). This result is reasonable and provides a further validation of PB model. So, in urban slope analysis, where PB diagnostic is necessary, statistical and PB modelling may play equally supportive roles in landslide hazard assessment. 相似文献
17.
HydrIS:一个用于地下水管理的开放的GIS决策支持系统——以Morocco为例(英文) 总被引：1，自引：0，他引：1
A regional groundwater management system has been elaborated, integrating Relational Database Management System (RDBMS) and
various web services. It consists of web geospatial application so-called HydrIS ( Hydrogeological Information System) based
on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrIS permits delivery
of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium (OGC). The protocols
used for exchanging data are also derived from OGC standards, i.e., WMS (Web Mapping Service), WFS (Web Feature Service),
and WCS (Web Coverage Service). Finally, a geoportal was developed, which consists of client-applications that communicate
with different Web Services (WMS, WCS, and WFS) through http-requests.
A prototype for web-based GIS application was designed using the deegree Framework to provide systematic interfaces and functions.
This system was developed to demonstrate the value of making hydrogeological data more widely accessible through client/server
architecture. This experience and knowledge already gained in this project will be a source for technology transfer and policy
decisions. Otherwise, this will enable user groups to improve the management of their groundwater resources and contribute
to enhanced decision support capabilities.
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