Rare earth element geochemistry of the Late Quaternary tephra and volcano-clastic sediments from the Pachuca sub-basin, north-eastern Basin of Mexico

chondrite normalized ree patterns, fractionations of light (la/sm), heavy (gd/yb) and total (la/yb) ree and eu anomalies of the late quaternary multi-layer tephra fall deposits and overlying volcano-clastic sediments deposited in the pachuca sub-basin (north-eastern basin of mexico) are studied to characterize their geochemical signatures. the ree geochemistry is compared with mineralogical abundances and multi-element concentrations to identify the possible source terrains contributing sediments into the basin. the basalt to basaltic-andesite tephra deposits have chemical compositions comparable to the rocks from apan-tezontepec volcanic field and consist of plagioclase, pyroxene and olivine. they are characterized by lower total ree abundances, lower light and heavy ree fractionations and a positive eu anomaly. the overlying sediments show significantly different ree characteristics and can be divided into two different groups (i.e. i and ii). the geochemical composition and ree patterns of group i (15-17 m, 4.6-9.6 m and 2-4.6 m depths) are comparable to the tephra deposits and suggest a mafic provenance. they are characterized by the absence of the eu anomaly and lower total ree concentrations compared to group ii. in group ii (9.6-15 m and 0-2 m depths), higher total ree, a negative eu anomaly, abundant k-feldspar and enriched zr, y and th indicate felsic source terrains containing heavy minerals such as allanite, monazite and zircon.