Mineralogy and Geochemistry of Major, Trace and Rare Earth Elements in Sediments of the Hypersaline Urmia Salt Lake, Iran

Urmia Salt Lake（USL） is a hypersaline lake located at the NW corner of the Iran platform. The lake area is estimated to have been over 5000 km2 at one point, but has now decreased to <1000 km2 in the last two decades. It contains 4.6×10～9 tons of halite and other detrital and evaporative minerals such as calcite, aragonite, dolomite, quartz, feldspars, augite and sylvite. This study examined the mineralogy and geochemistry of bed sediments along the mid-east toward NE bank sediments collected from 1.5 meters depth and nearby augite placer. Due to the diverse lithology of the surrounding geology, bed sediments vary from felsic in the mid-east to mafic in the northeast. Weathering of tephrite and adakite rocks of the Islamic Island at the immediate boundary has produced a large volume of augite placer over a 40 km length, parallel to the shoreline. Based on the study result, weathering increases from south to north and the geochemistry of the sediments shows enrichment of Mg O, Ca O, Sr and Ba associated with Sr deployment in all samples. Rare earth elements（REE） patterns normalized to the upper continental crust（UCC） indicated LREEs enrichment compared to HREEs with an elevated anomaly of Eu, possibly due to surface absorbance of Mn and Fe minerals, associated with Sr elevation originating from adakites in the lake basin vicinity.