مقالههای Ghomi Mohammad
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
اطلاعات انتشار: Iranian Journal of Earth Sciences، پنجم،شماره۱، Apr ۲۰۱۳، سال ۰
تعداد صفحات: ۸
The Mighan Playa is the largest playa in Markazi Province. Sedimentary and soil structures show that during all phases the playa was ephemeral. The duration and frequency of flooding varied causing variations in the relative amounts of accumulation, and soil formation. The clastic fraction of the playa sediment consists of quartz, mica and chlorite while the non–clastic evaporite fraction is dominated by gypsum, calcite, glauberite, thenardite and halite. Using the principle of chemical divides, such variations in mineralogy have been explained in terms of a change in brine chemistry from Na–Ca–Mg–SO4–Cl to Na–SO4–Cl type. It is also suggested that at an earlier stage, Mighan playa brine underwent evaporation under the conditions of Ca>alkalinity whereas in more recent times, the evaporite mineralogy has developed with alkalinity>Ca. The shallow depth cores are divided into distinct geochemical units based on elemental ratios. Units I and III reflect high chemical weathering whereas the middle unit, II, indicates relatively low weathering and enrichment in evaporates
اطلاعات انتشار: Iranian Journal of Earth Sciences، پنجم،شماره۲، Oct ۲۰۱۳ ، سال ۰
تعداد صفحات: ۱۲
This paper presents results of an assessment of dominant hydro–geochemical processes controlling groundwater chemical composition, using an integrated application of cluster analysis and factor analysis. The area is located in south of saline playa and in Arak city. Cluster analysis classified samples into two main clusters according to their dominant chemical composition: cluster A (dominant composition: Ca, Cl and SO4) and cluster B (dominant composition: Ca–HCO3). These clusters were in turn described by factor analysis. Results of factor analysis and geochemical interpretation suggest that spatial variation of groundwater quality in the area is influenced by different processes: Analyses revealed three major sources of variation in groundwater composition: carbonat and silicate mineral weathering, saltwater intrusion and anthropogenic contamination. Factor 1 shows processes of dissolution of C and SO4 evaporative salts (for samples close to Arak playa). Factor 2 exhibits strong positive correlation in Zn and Cu and show anthropogenic or industrial sources. Factor 3 exhibits HCO3 and NO3 and is resulted from weathering of carbonate and silicat minerals by percolating water and disposal of domestic wastes.
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