U-Pb geochronology of the El Jadida rhyolite and relation to possible Lower Cambrian recycling (Coastal block, Moroccan Meseta).

The El Jadida (Mazagan) dome, whose existence was reported as early as 1934 by Yovanovitch and Freys, constitutes one of the first outcrops of the Moroccan Meseta where the Precambrian (PIII?)-Paleozoic (Lower Cambrian?) boundary was established (Gigout, 1951; Cornée et al., 1984). Since then, it is listed as one of the few locations where the basement of the Moroccan Variscan belt can be observed (Hoepffner et al.. 2005; Michard et al., 2010).Despite, the absence of geochronological and biostratigraphic precise data to constrain the time interval recorded here, there are stratigraphic similarities that allow a correlation with the Ediacaran-Cambrian geological record of Anti-Atlas belt (Cornée et al., 1984). In this study, we developed a petrographic, geochemical and U-Pb geochronological study using zircon extracted from: (i) the El Jadida rhyolite with the aim of characterizing the magma source and estimate the age of crystallization; (ii) a microbreccia sampled at the base of the El Jadida Dolomitic Formation for determining provenance

Sedimentary provenance of siliciclastic rocks from the Lalla Mouchaa Calcschists Formation (Coastal Block, Western Rehamna): Evidence of denudation of ca. 2 Ga basement in the Moroccan Meseta.

Paleoproterozoic basement rocks (ca. 2Ga) are scarce along the European and North African Paleozoic mountain chains (Fig.1a). In Morocco, ca. 2.2-2Ga granitic rocks (Gasquet et al., 2008; Kouyaté et al., 2013) have been exclusively reported in the Western Anti-Atlas at southwest of the Anti-Atlas Major Fault, (Choubert, 1963). In Eastern and Central Anti-Atlas and in the Moroccan Meseta, the existence of a Paleoproterozoic basement has only been recognized through indirect evidence (Gasquet et al., 2008; Michard et al., 2010). In the Anti- Atlas belt, ca. 2Ga detrital zircon grains are found in the Ediacaran siliciclastic rocks of the Bou Salda, Saghro and Taghdout groups (Abati et al., 2010). In the Moroccan Meseta, Paleoproterozoic (ca. 2Ga) zircon grains were extracted from gneiss and granitic xenoliths found in Triassic lamprophyre dykes, and from Carboniferous granophyric microgranite intrusions of central Jebilet (Dostal et al., 2005, Essaifi et al., 2003). Recently, a porphyritic rhyolite from the Rehamna Massif was dated at ca. 2.05Ga (Pereira et al., 2015), demonstrating for the first time, the exposure of the Eburnian basement in the Western Meseta. These Eburnian arc-related magmatic rocks, which are exposed to the south of the Permian Sebt Brikiyine granite in the core of anticlines from the Lalla Mouchaa Anticlinorium, are allegedly unconformably overlained by transgressive siliciclastic and carbonate beds (Corsini, 1988; Pereira et al., 2015). At north of the Sebt Brikiyine granite the probable Lower Cambrian sequence (Lalla Mouchaa Calcschists Formation; Guezou & Michard, 1976; Corsini, 1988) comprises a basal unit of microbreccias, arkosic sandstones and siltstones (lower member) that pass towards the top to centimeter-thick beds of calcschists interbedded with limestones and dolomites (upper member) that are conformably overlain by the “Paradoxides Shale Formation” composed of siltstone, greywacke and sandstone with Middle Cambrian fauna. In order to study the potential sources of the Lalla Mouchaa Calcschists Formation (probable Lower Cambrian), we have sampled a microbreccia at the Koudiat El Hamra region, for U-Pb geochronology on detrital zircon. This foliated microbreccia is composed of elongated Kfeldspar and quartz phenocrysts surrounded by a fine-grained matrix. Detrital zircon grains gave 206Pb/238Ub ages that in the Probability density plot curve are distributed by two main age peaks at ca. 2.05Ga and ca. 2.03Ga (Fig.1b), yielding a 206Pb/238U age-weighted mean of ca. 2.04Ga (El Houicha et al., 2018). The obtained U-Pb results point to a provenance from a Paleoproterozoic source, suggesting a possible contribution from rocks of the same age of the 2Ga porphyritic rhyolite exposed at south of the Sebt Brikiyine granite. Thus, there is a possibility that the Paleoproterozoic basement extends bellow the Paleozoic and Neoproterozoic sequences of the Rehamna massif

Studies on Aluminothermic Reduction of Manganese ore for Ferro-Manganese Making

It is well known that lowering the carbon content offerro-alloy increases the value of the metal. This grade of ferro-alloy results in lowering the cost of production in steel melting stage. Alurninothermic process produces carbon free ferro-alloys. In this paper, details of investigations onferro-manganese making are given.- Influence ofpre-reduction of manganese ore to Mn7O3 and Mn .,stage, excess aluminium overstoichiometric requirement, addition of fluxes etc., on metal yield is discussed. Metal yield of 58-64% on 10 kg scale with alloy composition of Mn-83%, Fe-13%, Si-1.4 to 2%, Al-0.008% and P-0.16% has been successfully achieved at the Laboratory

Zircon U-Pb geochronology and geochemistry of Cambrian magmatism in the Coastal Block (Oued Rhebar volcanic complex, Moroccan Meseta): Implications for the geodynamic evolutionary model of North-Gondwana

U-Pb dating (SHRIMP) of magmatic zircons from an intermediate-mafic agglomerate of the Oued Rhebar Volcanic Complex (Coastal Block, Western Meseta) yielded a weighted mean age of 507 ± 5 Ma. The obtained middle Cambrian age (Series 3, Stage 5) seems to be the best estimate for the crystallization of the ORVC volcanic rock, providing a maximum depositional age for the overlying Bouznika volcanosedimentary Formation. The ORVC rock is representative of middle Cambrian crust generation in North-Gondwana, but contains Ediacaran (ca. 546-542 Ma) and early Cambrian (ca. 536-526 Ma) inherited zircon which might be derived from recycling of older continental crust. This geochemistry study corroborates the existence of calcalkaline rhyolites, basaltic andesites and andesites in the ORVC rocks, but also of the existence, albeit to a lesser volume, of tholeiitic basalt. The relative higher volume of calc-alkaline compared to tholeiitic signature might reflect, in some extent, contamination of depleted mantle-derived magmas by the upper continental crust, as has been proposed for the origin of the same age rift-related igneous rocks from North-Gondwana, as the Iberian correlatives

Smelting reduction reactions by solid carbon using induction furnace: foaming behaviour and kinetics of FeO reduction in CaO-SiO2-FeO slag

Smelting reduction process technology is progressing rapidly, and research to understand the reduction of FeO in molten slag and the associated foaming behaviour has gained importance. The present paper reports experimental data on the reduction of FeO in molten slag generated in a 30 kW capacity induction furnace. The influence of FeO content in the slag and temperature on the foaming and kinetics is discussed. The foaming index, a parameter describing the travel time of gas in the reactor, is shown to decrease with an increase in the superficial gas velocity. The quantitative dependence of the foaming index on slag properties viscosity, surface tension and density has been studied. The data have also been analysed to give an estimation of the activation energy for the reduction reaction. The reduction reaction, initiated by direct slag graphite contact, produces CO gas, which spreads into the molten slag bath causing foaming of the slag; further reduction of FeO proceeds mostly via indirect reduction. The rate of reduction is found to depend directly on the initial FeO content. An increase in temperature increases the rate of reduction, which has an activation energy of 118 kJ mol(-1) of FeO. The results indicate that transport of FeO in the liquid phase is the rate controlling step. The major findings are in agreement with those reported by earlier investigators

Caractérisation et approche structurale de verres du systeme La2O3–MgO–B2O3

In this paper, a vitreous domain of the ternary system: xLa2O3–yMgO–zB2O3 characterised by X-ray diffraction is shown. Structural approach using vibrational spectroscopy and optical probe is realized for some of these glasses and compared to crystalline LaMgB5O10..

Distributed CNN Inference on Resource-Constrained UAVs for Surveillance Systems: Design and Optimization

Unmanned aerial vehicles (UAVs) have attracted great interest in the last few years owing to their ability to cover large areas and access difficult and hazardous target zones, which is not the case of traditional systems relying on direct observations obtained from fixed cameras and sensors. Furthermore, thanks to the advancements in computer vision and machine learning, UAVs are being adopted for a broad range of solutions and applications. However, deep neural networks (DNNs) are progressing toward deeper and complex models that prevent them from being executed onboard. In this article, we propose a DNN distribution methodology within UAVs to enable data classification in resource-constrained devices and avoid extra delays introduced by the server-based solutions due to data communication over air-to-ground links. The proposed method is formulated as an optimization problem that aims to minimize the latency between data collection and decision-making while considering the mobility model and the resource constraints of the UAVs as part of the air-to-air communication. We also introduce the mobility prediction to adapt our system to the dynamics of UAVs and the network variation. The simulation conducted to evaluate the performance and benchmark the proposed methods, namely, optimal UAV-based layer distribution (OULD) and OULD with mobility prediction (OULD-MP), was run in an HPC cluster. The obtained results show that our optimization solution outperforms the existing and heuristic-based approaches. 2014 IEEE.Qatar UniversityScopu

Evidence of a Paleoproterozoic basement in the Moroccan Variscan Belt (Rehamna Massif, Western Meseta)

For the first time, an Eburnian magmatic event has been identified in the Rehamna Massif (Moroccan Variscan Belt, Western Meseta) located north of the South Meseta fault. The best estimate of the crystallization age of rhyolitic porphyry is given by a weighted mean 207Pb/206Pb age of 2050.6 ± 3 Ma (Rhyacian-Orosirian). The new U–Pb age obtained for rhyolitic porphyry from the Rehamna Massif is of great relevance for improving geological knowledge about the boundaries ofthe WAC because:(i)it overlaps the older Eburnian magmatic event described in the Anti-Atlas belt and the Icartian magmatic event of the European Variscan Belt; (ii) this suggests that exists Paleoproterozoic basement in the Western Meseta, a hundred kilometers further to the north of the South Meseta fault, as old continental crust slivers preserved in the Cadomian and Variscan belts; and (iii) this means that the Cambrian transgression in the Western Meseta probably took place based on a more complex structural architecture affecting the Precambrian basement composed not only of Ediacaran rocks, as has been suggested in the literature, but also with Paleoproterozoic rocks (ca. 2.05 Ga) as discovered in this study