Spatial and temporal characteristics of volatiles in the Cenozoic mantle beneath eastern China

Abstract

Subduction of the paleo-Pacific Plate has transported volatiles from the surface to the interior of the Earth and significantly altered the chemical and physical properties of the Cenozoic mantle beneath eastern China. However, the characteristics of volatiles other than H₂O in the Cenozoic mantle remain poorly constrained. To describe the spatiotemporal distribution of volatiles, including S, Cl, and H₂O, in the Cenozoic mantle beneath eastern China, we performed reheating experiments and determined the composition of olivine-hosted melt inclusions from a large area (5.9 × 10⁵ km²) of basalts. Calculations of the mantle-source compositions indicate that the Cenozoic mantle in North China is enriched in S but deficient in H₂O and Cl, relative to that in South China. The distinctive features of volatiles likely arise from the different types of recycled materials in the mantle sources (such as Cl-containing sediments, carbonates, or sulfides in the altered oceanic crust) and their different proportions (from <1.7 % to 7 % of subducted sediments). Both the North China and South China mantles reached high volatile contents at 17.5–11.9 Ma, indicating that the activation of the South China mantle and the destruction of the North China Craton may have occurred simultaneously. These novel findings improve our understanding of mantle evolution beneath eastern China and will help in evaluating the contributions of slab subduction to the spatiotemporal heterogeneity of the lithospheric mantle during the Cenozoic.