The control of Indonesian Throughflow and sea level changes on the paleoclimatic variability along the northwest Australian margin over the last~800 kyr: Insights from clay mineral, grain size and radiogenic isotope records at IODP Site U1483

Mid-Late Quaternary sediments collected from high sedimentation Site U1483 of the International Ocean Discovery Program (IODP), located off the Scott Plateau of the northwest Australian margin were analyzed for clay mineral assemblages, radiogenic isotope, and siliciclastic grain size records, in order to reconstruct sediments provenance, ocean currents behavior and variability of Australian summer monsoon over the last ~800 kyr. Clay mineral fractions are mainly dominated by smectite, followed by moderate kaolinite and illite, and minor chlorite. Our provenance model suggests the Victoria and Ord Rivers of the Kimberley region as the primary sedimentary sources for Site U1483 over the past ~800 kyr. The Strontium-Neodymium-Lead (Sr-Nd-Pb) isotope values (87Sr/86Sr: 0.730-0.720, ƐNd: -8.22 to -10.73 and 206Pb/204Pb: 19.25 to 18.95) at Site U1483 are consistent with the isotope composition of northwest Australian sediments and indicate only a minor sediments contribution from the Timor region by ITF. Time-series variation in the clay mineral and grain size records indicate strong glacial-interglacial cyclicity, with small grain size, high smectite, and low kaolinite and illite during glacials, while interglacials are marked by a relative increase in kaolinite and illite, mean grain size, and decrease in smectite. (Kaolinite+illite+chlorite)/smectite and kaolinite/smectite ratios coupled with clay/silt ratio were adopted to indicate variability in the intensity of the ITF and Australian monsoon. High values of kaolinite/smectite and (kaolinite+illite+chlorite)/smectite ratios during the interglacials indicate a wet summer monsoon with high river discharge and a strong ITF. In contrast, during glacials, the low values of kaolinite/smectite and (kaolinite+illite+chlorite)/smectite imply a dry summer monsoon and a weak ITF. In addition, our proxy records display a variation shift around 450 ka which coincides with the timing of the Mid Brunhes Event (MBE) and marks the transition into extreme glacials-interglacials. The proxy records spectral analysis display concentration of power on 100-kyr, 41-kyr, and 23-kyr bands, implying that both high-latitude ice sheet and the precession-driven low-latitude processes influenced clay mineral sedimentation along the northwest Australian margin.