Geochemistry of the Krivoy Rog Banded Iron Formation, Ukraine, and the impact of peak episodes of increased global magmatic activity on the trace element composition of Precambrian seawater

摘要

Pure Superior-type Banded Iron Formation (BIF) samples from the Krivoy Rog Supergroup (Ukraine) are excellent archives of ambient Early Precambrian seawater. They show low concentrations of incompatible elements such as Zr, Hf, and Th, and shale-normalized Rare Earths and Yttrium (REYSN) patterns similar to those of modern seawater, i.e. heavy REYSN enriched patterns with positive La-SN, Gd-SN and Y-SN anomalies. Lack of Ce-SN and presence of positive Eu-SN anomalies indicate REY contributions to anoxic ferruginous seawater from high-temperature hydrothermal fluids.