Secular variation in the elemental composition of marine shales since 840 Ma: Tectonic and seawater influences

Marine shales, the most common lithology in the stratigraphic record, represent an archive of long-term changes in sediment production, weathering intensity, and seawater chemistry through Earth history whose potential has been underexploited to date. In this study, we compiled compositional data for 14,531 samples from 268 shale and mud units ranging in age from the early Cryogenian (840 Ma) to the Recent. We examined secular variation in the...