Spatiotemporal Discharge Variability of the Doce River in SE Brazil During MIS 6 and 5

The modern precipitation balance in southeastern (SE) Brazil is regulated by the South American summer Monsoon and threatened global climate change. On glacial-interglacial timescales, monsoon intensity was strongly controlled precession-forced changes insolation. To date, relatively little known about spatiotemporal distribution of tropical SE resulting variability fluvial discharge on timescales. Here, we present X-ray diffraction-derived mineralogical data for 150–70 ka period (marine isotope stage (MIS) 6 to MIS 5) from Doce River basin. This area sensitive monsoonal due its proximity Atlantic Convergence Zone. data, obtained a marine sediment core (M125-55–7) close river mouth (20°S), show pronounced suspension load’s composition precessional While ratio silicates carbonates displays precession-paced changes, carbonate-free fraction discriminates between two assemblages which vary glacial interglacial time scales, with only visible 5. first assemblage, dominated high contents kaolinite gibbsite, indicates intensified lowland erosion mature soils. second one, characterized higher well-ordered illite, quartz albite, points immature soils upper Basin. High silicate prevailed late indicate soil along steepened topographic gradient. illite-rich mineral assemblage more abundant 5, particularly during times austral insolation, indicating strong rainfall intense physical catchment. When weakened lower again, indicative runoff catchment dominant erosion.