Description: We examine the paleoceanographic record over the last ∼400 kyr derived from major, trace, and rare earth elements in bulk sediment from two sites in the East China Sea drilled during Integrated Ocean Drilling Program Expedition 346. We use multivariate statistical partitioning techniques (Q‐mode factor analysis, multiple linear regression) to identify and quantify five crustal source components (Upper Continental Crust (UCC), Luochuan Loess, Xiashu Loess, Southern Japanese Islands, Kyushu Volcanics), and model their mass accumulation rates (MARs). UCC (35–79% of terrigenous contribution) and Luochuan Loess (16–55% contribution) are the most abundant end‐members through time, while Xiashu Loess, Southern Japanese Islands, and Kyushu Volcanics (1–22% contribution) are the lowest in abundance when present. Cycles in UCC and Luochuan Loess MARs may indicate continental and loess‐like material transported by major rivers into the Okinawa Trough. Increases in sea level and grain size proxy (e.g., SiO2/Al2O3) are coincident with increased flux of Southern Japanese Islands, indicating localized sediment supply from Japan. Increases in total terrigenous MAR precede minimum relative sea levels by several thousand years and may indicate remobilization of continental shelf material. Changes in the relative contribution of these end‐members are decoupled from total MAR, indicating compositional changes in the sediment are distinct from accumulation rate changes but may be linked to variations in sea level, riverine and eolian fluxes, and shelf‐bypass processes over glacial‐interglacials, complicating accurate monsoon reconstructions from fluvial dominated sediment.

Description: We reconstruct the provenance of aluminosilicate sediment deposited in Ulleung Basin, Japan Sea, over the last 12 Ma at Site U1430 drilled during Integrated Ocean Drilling Program Expedition 346. Using multivariate partitioning techniques (Q-mode factor analysis, multiple linear regressions) applied to the major, trace and rare earth element composition of the bulk sediment, we identify and quantify four aluminosilicate components (Taklimakan, Gobi, Chinese Loess and Korean Peninsula), and model their mass accumulation rates. Each of these end-members, or materials from these regions, were present in the top-performing models in all tests. Material from the Taklimakan Desert (50–60 % of aluminosilicate contribution) is the most abundant end-member through time, while Chinese Loess and Gobi Desert components increase in contribution and flux in the Plio-Pleistocene. A Korean Peninsula component is lowest in abundance when present, and its occurrence reflects the opening of the Tsushima Strait at c. 3 Ma. Variation in dust source regions appears to track step-wise Asian aridification influenced by Cenozoic global cooling and periods of uplift of the Tibetan Plateau. During early stages of the evolution of the East Asian Monsoon, the Taklimakan Desert was the major source of dust to the Pacific. Continued uplift of the Tibetan Plateau may have influenced the increase in aeolian supply from the Gobi Desert and Chinese Loess Plateau into the Pleistocene. Consistent with existing records from the Pacific Ocean, these observations of aeolian fluxes provide more detail and specificity regarding the evolution of different Asian source regions through the latest Cenozoic.

Description: Fe2+ was analysed photometrically (Hach Lange DR 5000 photometer) at 565 nm following the method of Collins et al. (1959). 1 mL of acidified sample (20 L of 1% ascorbic acid) was added to 50 μL of a ferrospectral reagent (Merck Chemicals) in disposable polystyrene cuvettes (Stookey, 1970). Samples with high Fe2+ concentrations were diluted with oxygen-free artificial seawater. PO43- concentrations were determined photometrically using the molybdenum blue method (Grasshoff et al. 1999) and a Hach Lange DR 5000 photometer. Highly sulfidic samples were spiked with 20 μL of 30% HCl and bubbled with argon for one minute to limit sulfide interference for PO43- analysis. NH4+ was measured by flow injection using a PTFE tape gas separator technique after Hall and Aller (1992). The precisions of the Fe2+, PO43- and NH4+ analyses were 1%, 7% and 6% respectively. Sulfate (SO42-), fluorine (F-) and bromine (Br-) was determined by ion chromatography (Metrohm 861 Advanced Compact IC, Metrohm A Supp 5 column, 0.8 mL min-1, conductivity detection after chemical suppression). Total dissolved hydrogen sulfide (H2S) was measured photometrically using the methylene blue method in samples that were fixed on board with ZnAc (Cline, 1969). The analytical precision for SO42- and H2S analysis was 2%. Dissolved calcium (Ca2+), barium (Ba2+), potassium (K+), silicon (Si4+), strontium (Sr2+) and magnesium (Mg2+) were determined in samples acidified by suprapure concentrated HNO3 (10 μl per ml of sample) by inductively coupled plasma optical emission spectroscopy (ICP-OES; axial plasma observation; Agilent 720) with a precision of at least 2%. Dissolved inorganic carbon (DIC) and non-purchable organic carbon (NPOC) were determined by direct injection to a carbon analyzer (analytikJena multiN/​C 2100s).

Description: Fe2+ was analysed photometrically (Hach Lange DR 5000 photometer) at 565 nm following the method of Collins et al. (1959). 1 mL of acidified sample (20 L of 1% ascorbic acid) was added to 50 μL of a ferrospectral reagent (Merck Chemicals) in disposable polystyrene cuvettes (Stookey, 1970). Samples with high Fe2+ concentrations were diluted with oxygen-free artificial seawater. PO43- concentrations were determined photometrically using the molybdenum blue method (Grasshoff et al. 1999) and a Hach Lange DR 5000 photometer. Highly sulfidic samples were spiked with 20 μL of 30% HCl and bubbled with argon for one minute to limit sulfide interference for PO43- analysis. NH4+ was measured by flow injection using a PTFE tape gas separator technique after Hall and Aller (1992). The precisions of the Fe2+, PO43- and NH4+ analyses were 1%, 7% and 6% respectively. Sulfate (SO42-), fluorine (F-) and bromine (Br-) was determined by ion chromatography (Metrohm 861 Advanced Compact IC, Metrohm A Supp 5 column, 0.8 mL min-1, conductivity detection after chemical suppression). Total dissolved hydrogen sulfide (H2S) was measured photometrically using the methylene blue method in samples that were fixed on board with ZnAc (Cline, 1969). The analytical precision for SO42- and H2S analysis was 2%. Dissolved calcium (Ca2+), barium (Ba2+), potassium (K+), silicon (Si4+), strontium (Sr2+) and magnesium (Mg2+) were determined in samples acidified by suprapure concentrated HNO3 (10 μl per ml of sample) by inductively coupled plasma optical emission spectroscopy (ICP-OES; axial plasma observation; Agilent 720) with a precision of at least 2%. Dissolved inorganic carbon (DIC) and non-purchable organic carbon (NPOC) were determined by direct injection to a carbon analyzer (analytikJena multiN/​C 2100s).