From plant roots to mountain roots: Impact of land plants on arc magmatism

Abstract The hypothesis that the evolution of land plants influenced arc magmatism offers a compelling link between Earth's biological evolution and plate tectonics. Land plants transformed terrestrial environments, increasing fluvial sediment residence times, intensifying chemical weathering, and increasing clay production. Incorporating muddier alluvial protolith into magmas resulted in a systematic increase in the strength of correlation between δ18O, which reflects the degree of surface weathering, and εHf, which indicates the age of the source material. The emergence of this εHf/δ18O correlation at ca. 450 Ma coincides with the expansion of land plants across a broad latitudinal range, from low to high latitudes. However, the extent to which this isotopic signal represents a global phenomenon, rather than a bias introduced by uneven geographic sampling of detrital zircon, has been questioned. We demonstrate that this shift in correlation persists within single long-lived magmatic provinces, supporting the hypothesis that the isotopic shift reflects a fundamental irreversible change in sediments assimilated into magmatic systems. This isotopic shift occurs in arc systems at various paleolatitudes, indicating no detectable dependence on latitudinally controlled climatic or biologic processes. Therefore, the post–450 Ma shift in arc magma composition remains a key indicator of changing Earth surface processes during the mid-Paleozoic.