Fractionation of rare earth elements in carbonate nodules of alluvial soils along a chronosequence
Journal
CATENA
Journal Volume
264
Start Page
109704
ISSN
03418162
Date Issued
2026-03
Author(s)
Abstract
Rare earth elements (REEs) have been detected in soil carbonate nodules, where their redistribution patterns can offer valuable insights into pedogenesis over various time scales. This study aimed to characterize the signature and fractionation of REEs in carbonate nodules of aged-alluvial soils along a chronosequence in the sub-humid coastal plain of southwestern Taiwan. Four Alfisol pedons containing carbonate nodules were sampled along a chronosequence, with soil ages estimated by the phases of shoreline transgression and regression to be 10,000 BP (Before Present), 8000 BP, 5000 BP, and 3000 BP. The nodules were predominantly comprised of calcite with minor amounts of quartz, chlorite, and illite. REEs concentrations were lower in the nodules than in the bulk soils (12.7–108 v.s. 132–315 mg kg−1). The upper continental crust normalized distribution patterns of REEs in the nodules differed from those of REEs in the corresponding bulk soils. Lower (La/Sm)N and (La/Yb)N indicated higher levels of heavy REEs (HREEs) in the nodules than in the bulk soils, implying that REEs fractionation occurred within the nodules during progressive pedogenesis. No trends in the REEs fractionation indices were discernible in the bulk soils, but the (Gd/Yb)N in the nodules decreased remarkably across the chronosequence. As a consequence, HREEs and the (Gd/Yb)N in the nodules of the studied chronosequence soils were suitable tracers separating the different pedogenic stages in principal component analysis. This study identifies systematic patterns in the REEs distribution of carbonate nodules that can serve as indicators of pedogenesis across temporal scales.
Subjects
Micromorphology
Paleoclimate
Pedogenesis
Shoreline change
Publisher
Elsevier B.V.
Description
Article number 109704
Type
journal article