Seasonal variation of the double diffusion processes at the Strait of Hormuz

Profiles of salinity and temperature were measured in the strait of Hormuz (SH) during the winter of 2012, spring and summer of 2013. To investigate the double diffusion (DD) processes, Turner (TU) angle values are calculated in all the stations in the SH. Different TU angle values correspond to salt fingering (SF), diffusive convection (DC) and stable stratification. The distributions of the two forms of DD were plotted vertically along transects in the eastern, central and western part of the SH, and corresponding DD processes were described. The results show that both SF and DC occurred in most part of the study area. Two different water masses (the Indian Ocean surface water and the Persian Gulf water) were evident at the SH, and SF and DC were evident at the interface of two water masses. Due to evaporation, SF occurred in the surface layer of most Stations throughout the year. In the eastern part of the SH, occurrences of DC were more feasible in wintertime. SF was the main phenomenon at the end of hot season. For central part, SF occurred throughout the year in water column. In the western part, water column was stable in summer and DC happened in most part of water column in winter.     

Biostratigraphy of Asmari Formation in Ghare Agha seyed of Farsan region,Chaharmahale Bakhtiari Province,Iran

The Asmari Formation consists of shallow marine sedimentary rocks deposited on ramp setting .Lar-ger benthic foraminifera collected from Asmri Formation are dominated by hyaline and porcelanouse forms , in-cluding Amphistegina, Nummulites, Archaias, Astrotrillina, Miogypsinella, Miogypsinoides, Lepidocyclina, Operculina, Spiroclypeous and Miliolids.The presence of Nummulites cf.vascus in the lower part of the forma-tion allows the age to be determined as Rupelian .The occurrence of Borelis pygmae is an index taxon of the Ru-pelian-Chattian and indicates Early Chattian of SBZ 21-22 in the study section .The first appearance of Mio-gypsinella akadagensis shows Late Chattian ( SBZ 23) and defines the upper boundary of the SBZ 21-22.The new data are the first evidences showing that the shallow marine Asmari Formation is attributed to Oligocene (Rupelian-Chattian) age for this region.     

Textural relations,P-T path,polymetamorphism and also geodynamic significance of metamorphic rocks of the Aligudarz-Khonsar region,Sanandaj-Sirjan zone,Iran

The metamorphic rocks of the Aligudarz-Khonsar region can be divided into nine groups: slate, phyllite, sericite schist, biotite-muscovite schist, garnet schist, garnet-staurolite schist, staurolite schist, mylonitic granite, and marble. In this metamorphic region, four phases of metamorphism can be identified (dynamothermal, thermal, dynamic and retrograde metamorphism) and there are three deformation phases (D1, D2 and D3). Paleozoic pelagic shales experienced prograde metamorphism and polymetamorphism from the greenschist to amphibolite facies along the kyanite geotherm. The metapelites show prograde dynamothermal metamorphism from the greenschist to amphibolite facies. Maximum degree of dynamothermal metamorphism is seen in the Nughan bridge area. Also development of the mylonitic granites in the Nughan bridge area shows that dynamic metamorphism in this area was more intense than in other parts of the AligudarzKhonsar metapelitic zone. The chemical zoning of garnets shows three stages of growth and syn-tectonic formation. With ongoing metamorphism, staurolite appeared, and the rocks reached amphibolite facies, but the degree of metamorphism did not increase past the kyanite zone. Thus, metamorphism of the pelitic sediments occurred at the greenschist to amphibolite facies (kyanite zone). Thermodynamic studies of these rocks indicate that the metapelites in the Aligudarz-Khonsar region formed at 490–550°C and 0.47–5.6 kbar.     

Spatial distribution and temporal trends of persistent organochlorine pollutants in sediments from Lake Maryut, Alexandria, Egypt

Organochlorine compounds (OCs) in surface and core sediments collected from Lake Maryut, Egypt, were examined to elucidate their distribution, ecological risk and historical trend. To our knowledge, this is the first study on residue levels of OCs in sediments from Lake Maryut. Concentrations of PCBs and DDTs were higher than other OCs, ranging from 3.06 to 388 and from 0.07 to 106 ng/g dry wt., respectively. The highest concentrations of OCs were found at stations near the discharge point of sewage and close to industrial areas. The distribution of DDT and its metabolites suggest no recent inputs into the lake environment. Contamination levels of sedimentary PCBs and DDTs, can be categorized moderate to high compared to other urbanized regions worldwide. Temporal trends in OCs levels were influenced by input pathways at two sites. Evaluation of ecotoxicological risks suggests that adverse biological effects are expected mainly in the main basin area.