Data of the paper "Volcanogenic Controls on Coupled Fe-S-P Cycling in a Lacustrine Basin: Deciphering Mechanisms of Extreme Organic Carbon Enrichment"

Black shales serve as primary archives of organic carbon, preserving critical records of elemental cycling dynamics within carbon sequestration systems. Nevertheless, achieving a comprehensive understanding of biogeochemical cycling processes in lacustrine shale systems remains challenging due to superimposed geological modifications during prolonged burial processes. This investigation employs an integrated stratigraphic-geochemical methodology to elucidate volcanic material-inducedbeij perturbations in Fe-S-P coupling mechanisms and their consequent impacts on organic carbon preservation within Upper Triassic lacustrine shales of the Ordos Basin, North China Platform. Petrographic analysis reveals that organic carbon enrichment demonstrates genetic associations with volcanic inputs, though peak carbon accumulation intervals stratigraphically lag behind tuffaceous depositional events. The volcanic inputs introduced substantial Fe, P, and S into the lacustrine basin. Volcanogenic atmospheric fertilization stimulated proliferation of coccolithophores, lamellibranch, and actinopterygian assemblages within the lacustrine ecosystem, yet sustained nutrient replenishment over million-year timescales proved geochemically untenable. Crucially, volcanic-derived phosphorus became effectively sequestered via iron oxide adsorption and biomineralization processes in sedimentary matrices during this stage. Sulfate influx modulated bacterially mediated redox pathways, enhancing bacterial sulfate reduction (BSR) while suppressing dissimilatory iron reduction (DIR), thereby transitioning the redox regimes to euxinic conditions. During this process, Fe³⁺ in phosphorus-bearing iron (oxides) was reduced to Fe²⁺ and subsequently removed via pyrite formation. Subsequent phosphate remobilization from phosphorus-rich sediments under anoxic bottom water conditions established a positive feedback mechanism that sustained lacustrine productivity over geological timescales, ultimately facilitating exceptional organic matter preservation. This research highlights lacustrine nutrient cycling dynamics as critical amplifiers of carbon burial efficiency following volcanic material perturbations, providing mechanistic insights into continental carbon sink operations and long-term sequestration processes.