Mineral Dust Coupled With Climate-Carbon Cycle On Orbital Timescales Over The Past 4 Ma

The behaviors between delta C-13(benthic) and delta O-18(benthic) are anti-phased after 6 Ma, and many mechanisms have been proposed to explain their behaviors. However, this question remains debated. Here, we reconstruct the interaction between mineral dust, global carbon cycle changes, and climate-cryosphere system since 4 Ma. Our results suggest that Asian and/or global dust fluxes may have transported the signal of periodic Arctic ice sheet variability to the deep-sea delta C-13(benthic) record by mediating the strength of oceanic biological pumping. This can explain why delta C-13(benthic) data show very similar orbital-scale variability to delta O-18(benthic) changes controlled by Arctic ice sheet variability. A sharp increase in global dust fluxes after 1.6 Ma resulted in a significant weakening of the 405 kyr long eccentricity variance in delta C-13(benthic) data. We propose that mineral dust may have been one of the most important factors controlling the anti-phase relationship between delta C-13(benthic) and delta O-18(benthic) over the past 6 million years.Plain Language Summary Many mechanisms have been proposed to explain the phase relationship between benthic carbon isotopes (which record global carbon cycle changes) and benthic oxygen isotopes (which record ice volume/temperature) over the past few millions years, but these are still debated. In this study, a comparison of variations in the global ice volume/temperature, the global carbon cycle, and mineral dust released from continental interiors has been conducted. We find that variations in these parameters were very similar over the past 4 Ma at timescales linked to orbital climate forcing. We suggest that mineral dust transports periodic signals linked to orbital forcing of Arctic ice sheet variability to the deep-sea record of Earth's carbon cycle by varying nutrient supply to the ocean, thus mediating carbon production/burial. Mineral dust may have played a role in controlling the anti-phase relationship between deep sea oxygen isotopes and carbon isotopes around 6 Ma.