Quantifying the contribution of sediment recycling in mantle: A case study of Early Cretaceous gabbroic intrusions in the northeastern North China Craton

Abstract

Subduction-driven recycling of crustal components plays a crucial role in shaping the compositional heterogeneities of the mantle. However, determining the metasomatic proportion and age of sediment recycling remains challenging owing to the overprinting influence of other slab contributions. This study focuses on two Early Cretaceous (126–123 Ma) gabbroic intrusions from the northeastern North China Craton (NCC), China, which provide insights into how subducted sediments modulate mantle compositions. The olivine gabbro has higher MgO contents and lower FC3MS (FeO^T/CaO - 3MgO/SiO₂) values, suggesting peridotite-derived melts, relative to the gabbro that originates from pyroxenite mantle sources. The two gabbroic intrusions exhibit arc-like trace element distribution patterns, along with enriched whole-rock Sr–Nd and zircon Hf–O isotopic compositions. These characteristics indicate their derivation from fluxed melting of sub-continental lithospheric mantle sources hybridized by melts derived from ∼5 % terrigenous sediments. Based on the three-stage Pb isotopic growth model, the metasomatized time of the mantle sources occurred in the Late Jurassic (160–150 Ma), which provides new geochemical evidence supporting the Late Mesozoic subduction of the Paleo-Pacific Plate beneath the Eurasian continent. Using the program ABS5, we conducted quantitative calculations to estimate the pressure and temperature of sediment melting, with 3.1–3.2 GPa and 838–842 °C. Thus, our findings not only illustrate the specific contributions (i.e., proportion and age) of sediments input into the mantle, while also highlight the significant role of mantle metasomatism driven by recycled sediments in creating mantle compositional heterogeneities.