Geological, petrological and geochemical studies indicated that there are two distinct types of granitoid rocks: older quartz diorites to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a meta-aluminous chemistry and a calc-alkaline character, with high MgO, Fe 2 O 3 , TiO 2 , CaO, P 2 O 5 , Sr and low SiO 2 , K 2 O, and Rb. Their major and trace elements data, together with low 87 Sr/ 86 Sr ratios (0.7029±0.0008) are indicative of I-type affinities. The second-and third-phase granitoids range from calc-alkaline to alkaline, respectively. The second-phase granitoids have a peraluminous chemistry and high relative to the third-phase granitoids. The corundum normative nature and field observations suggested that it was formed by partial melting of the lower crust. The third-phase granitoids are alkaline in nature and characterized by higher SiO 2 , Rb, Y, Nb and lower MgO, Sr and Ba values than the younger granitoids (phase II). They are A-type granitoids which were generated from below or within the existing continental crust.

Seventy nine bottom sediment samples were collected from Abu Dhabi area from Ghantoout area in the north east from Abu Al Abyad island to determine the regional distribution of concentration of trace metals and pollution levels in the studied area. In general, a negative correlation has been reported between trace metals concentration and total organic matter with the exception of Cu, Zn, Co and Cr. A negative relation between trace metals concentrations and carbonate content was also found in the area of study. The present study focuses on the levels of copper, lead, iron, manganese, nickel, cadmium, zinc and vanadium in order to assess the extent of the environmental pollution and to discuss the origin of these contaminants in the sediments. The average concentrations of copper, zinc, lead, iron, manganese nickel, cadmium and vanadium are 4. 65, 11.94, 1.91, 2800, 92.26, 10.55, 0.082 and 11.43 µg/g respectively. These values are within the permitted levels in the marine activity areas and industrial activity areas, which means that trace metals are not derived from the pollutant sources.

The ophiolite sequences of UAE, as a part of Oman ophiolite, represent both, mantle section and crustal section. The crustal part of the ophiolite sequences, consists of a layered series (cumulate peridotites and gabbros). This paper aims to overview geochemical character and some mechanical and physical features of the gabbroic rocks. The gabbros comprise troctolite, olivine gabbro, normal gabbro, gabbronorite, and uralitized gabbros. Geochemical features indicate that they are tholeiitic and are formed in an arc-related tectonic setting. On NMORB normalized pattern of gabbros, the HFS-elements (P, Zr, Sm, Ti, and Y) show a flat pattern parallel to NMORB. In contrast, the LIL-elements (Rb, Ba, Th, Sr) are relatively more enriched than NMORB. The enrichment of LIL-elements over the HFS-elements and the depletion of Nb relative to other HFS-elements suggest involvement of subduction component in the depleted mantle source, and suggest that these rocks were formed in a supra-subduction zone tectonic setting.

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