In-situ concentrations of iron and aluminium in CXD31 sub-samples

Iron (Fe) availability in the ocean is strongly influenced by external inputs, including atmospheric deposition, sediment dissolution, and hydrothermal fluxes. To investigate long-term changes in Fe supply, we report in-situ measurements of Fe and aluminium (Al) concentrations from sub-samples of a Fe-Mn crust (CXD31) from the North Pacific Ocean, covering the last ~23 Myr. Iron concentrations exhibit a long-term increasing trend superimposed by several pronounced peaks, while Al concentrations co-vary with Fe during specific intervals, indicating variable terrigenous input. Periods of elevated Fe and Al concentrations at ~16.9, ~11.6, and ~2.7 Ma suggest intensified delivery of lithogenic material to the open ocean. We interpret these peaks as reflecting enhanced atmospheric dust fluxes associated with major phases of Asian inland aridification. The Fe–Al concentration dataset provides an independent geochemical archive for reconstructing variations in external Fe supply and supports a strong link between continental climate evolution and trace metal accumulation in the North Pacific.