كليدواژه :
حوضه هاي جغرافيايي , البرز مركزي , لاشك , منشأء يابي رسوبات
چكيده لاتين :
The geographical basin of Lashak is located in Nowshahr in Central Alborz, Iran. The aim of the research was to fin the orgin of the sediments in the basin. To achieve the aim we analyzed 40 samples from sediments by XRF and XRD. Also we studied 25 thin sections from these samples. The petro graphical and mineralogical results show that the sediments have been originated from shale, sandstone and siltstone of Ruteh and Shemshak formations. The geochemical results show that the sediments are high in TiO2, A1203, Ag, Cu, Mo, Ni, V and low in MgO, MnO, CaO, Sr, Sb, As relative to Clarke standard. The sediments are mainly composed of clay minerals like mica, illite, kaolinite, montmorillonite, ploygurskite, nantronite, and chlorite, quartz and carbonate. The amount of ploygurskite is higher than other clays. The high PH and presence of carbonate is the main reason of formation this mineral.
