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Khorramābād, Iran

El Hadi H.,Science Faculty | Simancas J.F.,University of Granada | Martinez-Poyatos D.,University of Granada | Azor A.,University of Granada | And 5 more authors.
Precambrian Research | Year: 2010

The Bou Azzer ophiolite in the Moroccan Anti-Atlas represents the suture of the Neoproterozoic Pan-African orogen. The Bou Azzer inlier includes, from NE to SW, three main geological units: a volcanic-arc, an ophiolite and a continental platform. Several subduction-related plutons intrude the ophiolite and the volcanic-arc, and syn-to-late orogenic deposits unconformably cover the three terranes. The Eburnean (≈2. Ga) continental basement observed in other inliers of the Anti-Atlas appears not to crop out at Bou Azzer, where rocks traditionally attributed to that old basement are in fact Neoproterozoic rocks, either metagranitoids of the continental margin or ophiolitic metagabbros.The age of a metagabbro of the ophiolite is reported here for the first time, as 697 ± 8. Ma (SHRIMP U-Pb on zircons). U-Pb geochronological data are also presented for two syn-kinematic subduction-related plutons which, together with previous data, establish a time-span of ca. 655-635. Ma for these arc-type rocks. Moreover, the Oumlill granite, previously attributed to the Eburnean basement, has been dated as 741 ± 9. Ma.The earliest tectonometamorphic event affecting the ophiolite is recorded as a relic foliation and a garnet-rutile metamorphic assemblage, which might attest to an early peak-pressure exceeding the 5-6. kbar medium pressure reported so far. Thus, we suggest a first stage of ophiolite underthrusting below a volcanic-arc, followed by ophiolite exhumation and the concomitant development of the main low-grade planar-linear tectonic fabric. The ages of the calc-alkaline, syn-kinematic subduction-related plutons (655-635. Ma) might be taken as the end of subduction and the beginning of the ophiolite exhumation-obduction.The author's work in the Bou Azzer region supports the ophiolite-continental platform interpretation of Leblanc (1975) and Leblanc and Moussine-Pouchkine (1994), rather than the tectonic mélange interpretation proposed by Saquaque et al. (1989b) and others. A recumbent anticlinal and the basal thrust of the ophiolitic terrane are the main macrostructures formed during the obduction stage, characterized by top-to-the-W/SW kinematics. This deformational event is also recorded in the rocks of the underlying continental platform. A syn-orogenic unit, namely the Tiddiline Formation, unconformably overlies the arc volcanics, the ophiolite and the continental platform. Further collisional deformation affected the Tiddiline sediments, giving way to ESE-WSW striking upright folds and oblique reverse faults. The latest structures in this Neoproterozoic suture were left-lateral strike-slip faults, pointing to an increase in the left-lateral component of the continental collision. © 2010 Elsevier B.V. Source

Carretero M.I.,Crystallography | Pozo M.,Science Faculty | Martin-Rubi J.A.,Geological Survey of Spain | Pozo E.,Geological Survey of Spain | Maraver F.,Complutense University of Madrid
Applied Clay Science | Year: 2010

All four peloids currently used in Spanish spas and from Lo Pagán lagoon sediment have been characterized mineralogically and chemically. They range in composition from smectites-rich to complex mixtures or even peat-clay mixtures. The peloids were mixed with artificial sweat and stirred for 1h (EN 1811:1998. +. A1: 2008) at 45°C (±2°C), simulating the thermal-therapy action commonly utilized in the spas. Later the leached extract was analyzed chemically after centrifugation and separation. In the leached sweat extract the concentration of 31 elements, including essential and/or potentially toxic elements, was determined by means of ICP-MS, ICP-AES and AAS.The principal leached elements are Na, Ca, Mg and K (between 29,000μg/g and 50μg/g). The quantity of Na, Mg and K after leaching is related to the composition of the mineral-medicinal water and the mineralogical composition (smectite content) of the raw material. However the leaching of Ca is related more to the presence of calcite and aragonite in the peloid used than to the composition of the mineral-medicinal water.Other elements are also leached in smaller proportions: Si and Sr (<45μg/g, except Sr: 197.5μg/g in Lo Pagán peloid); Ba and B (<6μg/g, except B: 42.9μg/g in Lo Pagán peloid); Al and Li (<2μg/g); Fe, Mn, Mo and V (<0.4μg/g, except Fe and Mo: 1.5μg/g in Lo Pagán peloid); and As, Sb and U (<0.1μg/g). Heavy metals such as Cu, Ni, Pb and Zn are ab/adsorbed from the sweat to the peloid leading in most cases to their removal from the leached extract. The other trace elements (Ag, Be, Cd, Co, Cr, Hg, Rb, Se, Th and Tl) are not leached by the Spanish spas peloids or leached at a concentration below 0.05μg/g in the case of the natural lagoon peloid.Of all the peloids studied, the highest quantities of elements were leached from the Lo Pagán peloid due to the hypermarine, sodium-chloride-type of lagoon water where the peloids originate.It is noteworthy that the content of potentially toxic elements (Ag, As, Be, Cd, Hg, Pb, Sb, Se, Tl and Zn) in the leached extracts is negligible (less than 0.05μg/g). © 2010 Elsevier B.V. Source

Kebede S.,Science Faculty | Travi Y.,University of Strasbourg
Quaternary International | Year: 2012

Understanding the origin of the δ 18O and δ 2H content of meteoric waters is the initial step in using these isotopes in water resources, hydrological and hydro-climatic investigations. Specifically, isotopes of water are proven tools in a) constraining rate and mechanism of groundwater recharge, b) tracing movement of groundwaters, c) reconstructing past climate (rainfall amount, humidity and temperature) at various time scales, d) quantifying water flux across boundaries (e.g. evaporation rates, mixing), and e) complementing regional and global climate models. The δ 18O and δ 2H values in rainfall waters of Ethiopia have long been recognised as a 'regional anomaly'. Regardless of the station's high altitude (2360 m asl) and the region's low mean annual temperature (16 °C), two conditions that would otherwise lead to relative isotope depletion, the rains show the highest 18O composition with no sign of effect of evaporative enrichment (as revealed by d-excess). This enrichment is also reflected in other local meteoric waters (shallow groundwaters, lakes, ambient vapour and rivers). Here, the δ 18O and δ 2H of 600 lake water samples, 3000 groundwater samples, and rainfall isotope data base from IAEA/WMO stations at Addis Ababa have been used to show the linkage between rainfall derivation processes and isotope signals. The major sources of moisture in Ethiopia are recycled moisture from continental sources for western and northern Ethiopia, and direct moisture from the Southern Indian Ocean for eastern lowlands of Ethiopia. Southern Ethiopia is influenced by South Indian Ocean moisture, which is characterised by relatively depleted 18O and 2H. Spatial variation (altitude and latitude) in 18O and 2H is weak, with altitude effect accounting for 0.1‰/100 m depletion in δ 18O. Detailed investigation of the relation between isotope pattern and isotope effects (amount, seasonality, temperature, etc.) shows that these effects are not pronounced. The -4.5‰ δ 18O shift recorded in deeper groundwaters and other paleo-climate achieves (from the current wt. mean rainfall value of -0.5‰) can only be explained by a shift in source of moisture, such as the northward penetration of the South Indian Ocean moisture into the Ethiopian highlands, or changes in evaporation conditions at the source. © 2011 Elsevier Ltd and INQUA. Source

The present work focused on the design of a drug delivery system (DDS) based on pH-sensitive hydrogel. The hydrogels were prepared via graft copolymerization of mixtures of acrylic acid (AA) and 2-hydroxy ethyl methacrylate (HEMA) onto starch backbones by a free radical polymerization technique. Sodium bicarbonate (NaHCO 3) was added to function as a foaming agent under acidic conditions, rendering the hydrogels to be porous. The porous structure of the hydrogel was essential in this system to yield a large surface area so that 5-fluorouracil (5-FU) release could be facilitated. The hydrogel, thus prepared, possessed a porous structure as determined by scanning electron microscopy. The water absorbency of the hydrogels was measured in solutions with pH levels ranging from 1 to 13. The starch-based hydrogel exhibited a pH-responsiveness character such that a swelling-deswelling pulsatile behavior was recorded at pH levels of 2 and 7. Using the drug 5-FU as a model molecule, the in vitro controlled drug-release behaviors of these hydrogels were investigated. The results indicate that the main parameter affecting the drug-release behavior of hydrogels is the pH of the solution. The release rate of 5-FU from hydrogel at pH 7.4 was faster than that at pH 1.2 due to the shrinkage of the hydrogel at pH 1.2. These results suggest that a porous hydrogel could potentially be a useful local delivery system to release drugs, primarily at a specific site of body. Source

A novel superabsorbent hydrogel was synthesized via crosslinking graft copolymerization of acrylacid (AA) abd buthylmethacrylate (BuMC) onto Carboxymethyl cellulose (CMC) backbones in a homogeneous solution. The methylenebisacrylamide (MBA) and Ceric amounium sulfate (CAN) were used as water-soluble crosslinker and initiator, respectively. Evidence of grafting was obtained by comparing FTIR. SEM spectra of CMC and the graft copolymer as well as solubility characteristics of the products. A mechanism for the superabsorbent hydrogel formation was also suggested. The affecting parameters onto swelling capacity of the synthesized hydrogel, i.e., concentration of AA/BuMC waight ratio, MBA as well as reaction temperature were systematically optimized for obtaining maximum absorbency as possible as. The swelling capacity of hydrogels was also measured in various salt solutions (LiCI, NaCI, KCl, MgCI 2, CaCI 2, SrCI 2, BaCI 2, and AICI 3). Due to high swelling ability in salt solutions, the hydrogel may be referred as "anti-salt superabsorbent" polymers. The overall activation energy for the graft copolymerization reaction was found to be 374 kJ/mol. The swelling kinetics of the hydrogels in distilled water was preliminary investigated. Source

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