Geochemistry of lamprophyre dykes,Wadi Sikait area,South Eastern Desert,Egypt

The Wadi Sikait area lies at about 95 km southwest of Marsa Alam City along the Red Sea Coast, Eastern Desert, Egypt. It is occupied by Precambrian rocks of ophiolitic mélange, metamorphosed sandstones (MSS), gab-bros and monzogranites which were later intruded by lamprophyre dykes and quartz veins. The lamprophyre dykes were extruded in NW-SE and NE-SW trends cutting monzogranites and metamor-phosed sandstones. The lamprophyres are porphyritic and composed of clinopyroxene, olivine and amphibole phenocrysts enclosed in a fine-grained groundmass of clinopyroxene, amphibole, opaque and lithium mica. The al-teration products are represented by amphibole (tremolite-actinolite and hornblende), carbonate, epidote, chlorite, iddingsite, clay minerals, limonite and serpentine. The Sikait lamprophyre dykes can be classified as alkaline lamprophyres characterized by silica contents rang-ing from 41.65 wt% to 50.88 wt% and Na2O>K2O. They are enriched in LILE, LREE and HFSE, but strongly de-pleted in compatible elements such as Cr and Ni relative to the primitive mantle. Sikait lamprophyres have moderate Zr/Hf (35.6-52.8) and Nb/Ta (20.5-22.5) ratios. Most of these features are attributed to the origin of these dykes from the metasomatized mantle affected by subduction-related fluid. These lamprophyres are compositionally similar to Salu lamprophyres in eastern China. The Sikait lamprophyre samples have high LREE (320×10-6-419×10-6) relative to HREE (20×10-6-33×10-6) with ratios (LREE/HREE=11.6-18.7) and no negative Eu anomaly (Eu/Eu*=0.9-1.04). The relative presence of posi-tive Ce anomaly (Ce/Ce*=1.04) in lamprophyre samples suggests the oxidizing condition under which the REEs were precipitated due to the common occurrence of fluorite and apatite.     

Use of natural chabazite–phillipsite tuff in wastewater treatment from electroplating factories in Jordan

Chabazite-phillipsite tuff from Tell Rimah volcano was evaluated in industrial wastewater treatment. Samples of two different size fractions have suitable zeolite content and cation exchange capacity, and are characterized by good attrition resistance and high packed bed density. Such properties enable these fractions to be used as ion exchangers under column operation condition. In the presence of high concentration of competing ions, such as Na⁺, Ca⁺² and K⁺, and under conditions of high total ionic concentration of toxic metals, the chabazite-phillipsite tuff exhibits successful performance in removing Cu⁺², Cr⁺³, Ni⁺², Zn⁺² and Fe⁺² from electroplating effluents. The factors that influence selectivity and efficiency of the zeolitic tuff were evaluated. The experimental work indicates that both selectivity and efficiency of the zeolite shows similar trends. The selectivity sequence exhibited by the zeolitic tuff is Ni⁺²>>Zn⁺² and Cr⁺³>Cu⁺²>>Fe⁺².