Enrichment factor (EF) of REEs in soil fractions of different grain sizes: Malatya–Kuluncak, Başören Village

This study investigated the enrichment factor (EF) and geochemical relationships of rare earth elements (REEs) in different grain size fractions of soils collected from Başören village, Kuluncak district, Malatya province, Türkiye. A total of 22 surface soil samples were collected and separated into five grain size fractions (< 75, 75–150, 150–180, 180–250, and > 250 μm), yielding 110 samples. Concentrations of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, and Y were determined by ICP-MS. EF values ​​were calculated using Al as the reference element, and Pearson correlation was applied to evaluate the relationships between REEs. Strong positive correlations were observed among most REEs (r = 0.999–1.000, p < 0.01), whereas weaker correlations were shown between Eu and Gd elements and La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Yb, Lu, and Y elements. Moderately positive relationships were determined between Al and REEs, with coefficients of determination (R2) ranging from approximately 0.33 to 0.54, indicating that REE distributions are primarily controlled by aluminosilicate minerals and fine-grained fractions. EF values ​​varied between sampling areas and grain size fractions. While negligible to moderate enrichment was observed in most samples, significant to very high enrichment was observed in some samples, particularly for Gd, Tb, Dy, Ho, and Yb. Samples T16 and T20 showed the highest enrichment levels, with Gd reaching very high enrichment classes (EF = 20–40). The results show that the spatial distribution and enrichment patterns of rare earth elements are largely influenced by lithogenic sources and grain size-dependent mineralogical characteristics.