The geochemical separation pattern and environmental behavior of ΣREE have been investigated in five different sedimentary systems related to Dar-e-Allo copper mine. For this purpose, the total concentration and sequential patterns of ΣREE elements were determined using multi-acid digestion and mBCR selective extraction method. The normalization patterns of ΣREE are drawn based on the NASC and UCC. concentration changes in the five sedimentary systems are very similar and the concentration of LREEs is higher than that HREEs, Opposite of the changes in the concentration of ΣREEs, more enrichment is seen in HREEs compared to LREEs. The geochemical separation patterns of ΣREEs in natural sediment and samples containing iron and manganese oxides is mainly dominated by the residual fraction. considering the different conditions of formation and stability in the samples taken from the waterways leading to the mine, evaporite deposits and sediments washed from the rock dump, the separation pattern of ΣREEs is controlled mainly with two parts soluble in Acid and reducible fraction. The trend of mobility and bioavailability from LREEs to HREEs increases with an upward slope. These results show that speciation, geochemical segregation pattern and environmental behavior for ΣREE lead to misinterpretation without considering key environmental factors.