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The source to sink process of terrigenous sediment from East Asia continent to the marginal seas is crucial for the understanding of land–ocean interaction and marine sedimentary process in the West Pacific continental margin. This paper presents element geochemical and Sr–Nd isotopic records of core CM97 in the Changjiang (Yangtze River) Estuary and core MD06–3040 on the inner shelf of East China Sea, aiming to reconstruct the Changjiang sediment source–to–sink transport process and its major controlling mechanism during the Holocene. Driven by the asynchronous evolution of the Indian and East Asian summer monsoon, the provenance of sediments accumulated in the Changjiang Estuary gradually changed from the upper catchment during the late glacial period to the mid–lower valley in the early–mid Holocene. With the intensive agricultural cultivation and urbanization development in the catchment during the late Holocene, the major source of Changjiang sediment into the sea shifted back to the upper catchment, again. The high–frequency ENSO activity may superimpose the effect of human disturbances on sediment source–to–sink process in the late Holocene. Therefore, the Holocene provenance evolution of Changjiang sediments in the East China Sea witnessed the changes of governing sediment erosion process within a large catchment from monsoon climate–dominated to anthropogenic driving. Our study also suggests the strong effect of hydrodynamics in coastal and shelf environments on sedimentary geochemical compositions, which deserves more attention in further sediment provenance study. [ABSTRACT FROM AUTHOR]

The inner shelf mud wedge of the East China Sea (ECS) is a high-sedimentation-rate fine-grained sediment unit that has preserved a continuous environmental evolution history since the last deglaciation. We present a high-resolution clay mineralogical study from Core MD06-3040 to semi-quantitatively evaluate terrigenous sediment contributions from various potential provenances throughout the Holocene. The results showed that the clay mineral assemblage is composed of dominant illite (34-49%), moderate smectite (16-41%) and chlorite (15-28%), and minor kaolinite (5-12%). Provenance analysis suggested that most fine-grained terrigenous sediments originated from the Yangtze River, with minor sediments derived from Taiwan island and negligible sediments from nearby Zhejiang and Fujian provinces. Time series variation in the contribution of the Yangtze source fluctuated in the range of 38-80%, whereas that of Taiwan island had a converse variation pattern from ∼10% to ∼55%, and the contribution of Fujian was relatively stable in the range of 7-11% throughout the Holocene. The fluctuations of clay mineral assemblages and variations of clay mineral contributions from different provenances of Core MD06-3040 were controlled by the variability of precipitation in the Yangtze drainage associated with periodic fluctuations in the East Asian monsoonal circulation. [ABSTRACT FROM AUTHOR]

We reconstruct the environmental evolution of the East China Sea in the past 14 kyr based on glycerol dialkyl glycerol tetraethers (GDGTs) in a sediment core from the subaqueous Yangtze River Delta. Two primary phases are recognized. Phase I (13.8-8 cal kyr BP) reflects a predominantly continental influence, showing distinctly higher concentrations of branched GDGTs (averaged 143 ng/g dry sediment weight, dsw) than isoprenoid GDGTs (averaged 36 ng/g dsw), high BIT index (branched vs. isoprenoid tetraethers) values (>0.78) and a fluctuating GDGT-0/crenarchaeol ratio ( R, varied from 0.52 to 3.81). Within this interval, temporal increases of terrestrial and marine influence are attributed to Younger Dryas (YD) (ca. 12.9-12.2 cal kyr BP) cold event and melt-water pulse (MWP) -1B (11.5-11.1 cal kyr BP), respectively. The prominent transition from 8 to 7.9 cal kyr BP shows a sharp decrease in BIT index value (<0.4) and increase in crenarchaeol, which marks the beginning of phase II. Afterwards, the proxies remain relatively constant, which indicates that phase II (7.9 cal kyr BP-present) is a shelf sedimentary environment with high stand of sea level. Overall, the BIT index in our record serves as a good marker for terrestrial influence at the site, and likely reflects the flooding history of the region. The TEX (TetraEther Index of tetraethers consisting of 86 carbons) proxy is not applicable in phase I because of an excess terrestrial influence; but it seems to be valid for revealing the annual SST in phase II (21.6±0.9°C, n=49). In contrast, the MBT'/CBT (Methylation of Branched Tetraethers and Cyclization of Branched Tetraethers) proxy appears to faithfully record the annual mean air temperature (MAT) (14.3±0.63°C, n=68) and presents an integrated signal over the middle and lower Yangtze River drainage basin. [ABSTRACT FROM AUTHOR]

Holocene changes in fine-grained sediment supplies to the East China Sea outer shelf were uncovered, through the mineralogical and geochemical analysis of Core B3 in the East China Sea Distal Mud (ECSDM). Based on the lithology, accelerator mass spectrometry (AMS) 14C dating, and sea-level change, Core B3 can be divided into two major units: transgressive stage (Unit 1: 12.5–6.8 kyr) and highstand stage (Unit 2: 6.8–0 kyr). Significant discrepancy of dolomite/calcite ratio in the fine fractions (<16 µm) of Changjiang (dolomite/calcite = 3:1) and Huanghe (dolomite/calcite = 1:22) sediments was used as a new uniqueness provenance tracer to distinguish these two riverine sources. Both of the dolomite/calcite ratio and rare earth elements fractionation parameters in the fine-grained sediment indicated distinct provenance shifts of Core B3 during the Holocene. Unit 1 of Core 3 (12.5–6.8 kyr) mainly consists of the reworked and resuspension sediments of the East China Sea shelf during the Holocene transgression, while Unit 2 sediments (6.8–0 kyr) are most likely sourced from the Changjiang and Huanghe. Moreover, mixing curves of dolomite/calcite ratio reveal that the ECSDM continuously received the Changjiang sediment since 6.1 kyr with notable fluctuations, whereas the Huanghe sediment supply began in 6.8 kyr but abruptly stopped during 4.2–0.8 kyr and then appeared again since 0.8 kyr. Temporal changes of the Changjiang and Huanghe fine-grained sediment contribution to the ECSDM are closely related to the formation of modern oceanic circulation system since 6.8 kyr (shelf sea-level change), the ‘4.2 kyr’ climate event, and the followed transition to cold and dry climate condition in the northeastern China (global climate change), as well as the artificial shift of lower Huanghe course in ad 1128 in the war against invasion of the northern nomadic nation (human activities). [ABSTRACT FROM AUTHOR]

AMS14C dating and analysis of grain size, major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea. Based on the environmentally sensitive grain size, clay mineral and major element assemblages, the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed. These three proxies, mean grain size (>9.71 µm), chemical index of alteration (CIA) and ratio of smectite to kaolinite in particular, show similar fluctuation patterns. Furthermore, 10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene; these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon. The cooling events correlated well with the results of the δ 18 O curves of the Dunde ice core and GISP2, which therefore revealed a regional response to global climate change. Four stages of the East Asia winter monsoon were identified, i.e. 8300-6300 a BP, strong and unstable; 6300-3800 a BP, strong but stable; 3800-1400 a BP, weak and unstable; after 1400 a BP, weak but stable. [ABSTRACT FROM AUTHOR]