Ree Y Distribution in Tremadocian Shelly Phosphorites (Toolse, Estonia): Multi-Stages Enrichment in Shallow Marine Sediments During Early Diagenesis

The Paleoecological Environment during the Ediacaran–Cambrian Transition in Central Guizhou Province, China: Evidence from Zn Isotopes

“…In addition, we normalized the REY data of each profile of the phosphorous rock series of the Taozichong Formation in Qingzhen to PAAS [63] and obtained REE distribution patterns (Figure 13a) and REY correlation maps (Figure 13b) for the samples in the study area. The study section of the Taozichong Formation has an obvious pattern of negative Ce anomaly and weak positive Eu anomaly, and the REE partitioning curve presents a hat-shaped pattern, which is also considered to be the rare earth partitioning feature of primary sediments [113]. The budge shape of the MREE pattern has been interpreted to mean that MREEs are preferentially incorporated through substitution mechanisms (bulk crystal control) in hydroxyapatite structures that interact with seawater [114].…”

“…However, the overall trend of the samples in the study area showed an increase in the ratio of (La/Sm) N (Figure 10b). The most likely reason is the flourishing of benthic organisms that exhibit biologically altered REE signals in seawater during their metabolic processes [115,116], resulting in a hat-shaped pattern of REEs in the study area, indicating that life activities preferentially clear Nd and transform it to Ho, and this also causes the enrichment factor peaks at Gd [113]. In addition, the correlation diagram of rare earth elements (Figure 13b) shows that there is a strong correlation between rare earth elements in the samples of phosphorus-bearing rock series in the study area, which generally indicates a relatively single source of sedimentary materials with strong homology [7,8,54].…”