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Quantifying the relative influences of anthropogenic activities and climate change on soil erosion and deposition during the Holocene, when both forces have been interacting is a complex problem. Analysis of long-term patterns in soil erosion and lake deposition in a basin can provide the basis for untangling the complexities of climate and anthropogenic forcings. In this paper, sedimentary sequences from Xingyun Lake are compared with simulated soil erosion rates in the basin to explore the relationship between river basin soil erosion and lake deposition during the Holocene in Yunnan, China. Modern soil erosion rates are calculated using RUSLE, while Holocene soil erosion rates are estimated using modern rates with reconstructed precipitation and vegetation cover sequences. Through this investigation, we found the following results. First, Holocene vegetation in the lake basin was mainly affected by climate change, and the vegetation experienced the same pattern of changes as the climate. Soil erosion and lake deposition rates, along with changes to vegetation cover, were synchronous with precipitation trends during the Holocene. Second, soil erosion and lake deposition have been exacerbated by human activities, such as deforestation and land reclamation in the Xingyun Lake basin. Finally, this study provides new insights into the effects by anthropogenic impacts and climate forcing on the processes of soil erosion and lake deposition on the millennium scale. [ABSTRACT FROM AUTHOR]

The Yaojiang Valley (YJV) of southern Hangzhou Bay was the birthplace of the well-known Hemudu Culture (HC), one of the representatives of Neolithic civilization in eastern China. To explore the magnitude of natural environmental effects on the HC trajectory, the palaeo-embayment setting of the YJV was studied in detail for the first time in terms of 3D Holocene strata supported by a series of new radiocarbon-dated cores. The results indicated that the local relative sea level rose rapidly during the Early Holocene in the YJV, reached its maximum flooding surface ca. 7900 cal yr BP, and then remained stable ca. 7900-7600 cal yr BP. Thereupon, an estuary stretching inland was first formed by marine transgression, and then, it was transformed to an alluvial-coastal plain by regressive progradation. The alluvial plain was initiated in the foothills and then spread towards the valley centre after sea level stabilization ca. 7600 cal yr BP. Accompanying these natural environmental changes, the earliest arrivals of foragers in the valley occurred no later than ca. 7000 cal yr BP. They engaged in rice farming and fostered the HC for approximately two millennia from ca. 7000-5000 cal yr BP as more lands developed from coastal progradation. The rise and development of the HC are closely associated with the sea level-induced landscape changes in the YJV in the Early-Middle Holocene, but the enigmatic exodus of the HC people after ca . 5000 cal yr BP is still contentious and possibly linked with the rapid waterlogging and deterioration of this setting in such a low-lying coastal plain as well as with associated social reasons. [ABSTRACT FROM AUTHOR]

The vast Dongting Lake in the middle Yangtze River basin, China, was occupied by Chinese Neolithic settlements starting 10 000 years ago, and rice cultivation there is probably the earliest in the world. The numerous Neolithic settlements identified by previous archaeological surveys represent the five major Neolithic cultural stages, i.e. the Pengtoushan (9000–7900 cal. yr BP), Zaoshixiaceng (7900–6800 cal. yr BP), Daxi (6800–5500 cal. yr BP), Qujialing (5500–5000 cal. yr BP), and Shijiahe (5000–4000 cal. yr BP). Using sedimentological and geoarchaeological approaches, this paper analyses the drivers of basin-scale settlement relocation in relation to lake-level fluctuations and monsoon climate variations in the Holocene. The relocation of Neolithic sites around the lake shoreline and on the adjacent floodplain, together with radiocarbon-dated stratigraphy, clearly indicates that the shape of the lake basin was an incised and elongated valley occupied by a lake in the early Holocene, which became a broader and shallower depression in the mid to late Holocene. The established lowest habitable base of the settlements positioned on the lake shore assists reconstruction of the change in lake level from 22 m at 9000 cal. yr BP to 26 m at 5500–4000 cal. yr BP, although higher and lower lake levels occurred during the intervening cultural stages. The pollen spectra reveal a warming trend throughout the Holocene with at least four major temperature cycles, driven by monsoon variations between temperate- and warm-humid conditions. In the early Holocene the climate changed from cool-dry to warm-humid, and this played a key role in developing the earliest Pengtoushan culture in the region. Subsequent climate fluctuations fit well with the advance and retreat of the lake shore, also coevally with Neolithic site movements in the lake region. In this study we show how geoarchaeological evidence can be used in environmental reconstruction during the Holocene. [ABSTRACT FROM AUTHOR]

Surface sediment samples from 17 sites in the Yantai coastal area, the northern Yellow Sea, China, combined with a sediment core were employed for geochemical and chronological analyses for the purpose of characterizing the temporal and spatial distribution of trace metals in sediments and their implications for anthropogenic processes. The results indicated that the spatial distribution of trace metals (Cr, Ni, Ti, Pb, As, Zn, Mn and Cu) in surface sediments was significantly contributed by the sewage discharges along the Yantai coast, and the coastal currents played a major role for transporting the pollutants to offshore. The temporal concentrations of trace metals in the sediment core based on the chronology determined by a combination of radionuclide Cs and Pb activity demonstrated that trace metal concentrations increased step-wisely over the last ca. 100 years, corresponding to the intensity of anthropogenic processes in the Yantai area. The high levels of Cu and As before the late 1970s indicated the agricultural emission from the application of pesticides. While, all the high-trace metal concentrations since the early 1980s could be seen as diagnostic indictors of increasing industrialization, urbanization and sewage discharge in the Yantai area. Although the potential ecological risk evaluation of trace metals in the coastal area suggests low-potential ecological risk at present, some trace metals, such as As and Pb need particular attention due to their slight contamination. [ABSTRACT FROM AUTHOR]

This paper examines the morphological development of the Yangtze River mouth, which has been diverting southeasterly (dextrally), according to historical (150 years) chart-based digital evolution model and on-site measured tidal flow data. We reveal a significantly narrowing of the northern river mouth branch from formerly >30 km wide to presently 10 km wide due to rapid siltation. Net siltation there, however, decreases gradually, which largely contrasts with the fact that the siltation has shifted to the southern river mouth area, as shown by many newly-emerged estuarine islands, sandy shoals and bifurcated branches. Our data have further demonstrated that the ebb flow that dominates in the study area changes its direction gradually from east to southeast from the inner to outer river mouth area, and its duration is much longer than the flood flow in the inner river mouth area, but nearly equal at the river mouth area. Accordingly, the sediment transport pathway has been diverted from east to southeast. We examine whether the Coriolis Force could explain the dextral diversion of the ebb flow and the altered morphodynamical processes. Although too weak to strengthen the tidal flows, the Coriolis Force can drag the ebb flow southeasterly, and so influence sediment transport paths at the estuarine scale. The Coriolis Force is limited in the inner river mouth, but substantial at and in the outer river mouth area when gradually free of estuarine topographic constraints. The Coriolis Force causes an offset in propagation of in-out flow directions at the river mouth area to form a slack water setting prone to estuarine siltation. Using the present approach also enables explanation of the morphological development of the Holocene Yangtze delta-coast that extends to the southeast. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Presents a study that used thermal ionization mass spectrometry to determine the ages of aragonite samples retrieved from sediments from the Daihai Lake in China. Results of uranium-series dating of carbonates from Daihai Lake; Procedure of the chemical pretreatment; X-ray diffraction curve of the sample; Grain-size characteristics of the sediments.

Although archaeological findings show the synchronous collapses of major well-documented Chinese Neolithic cultures around 4000 cal. yr BP, the driving mechanism for the phenomenon is still unclear and debatable. Spatial climatic features in China spanning this time period suggest a generally cold-dry setting. This is evidenced by 130 well-dated geological records at 97 sites located in climatically and topographically diverse regions, with occurrences of some extreme hydrological events like severe floods in the Chinese Loess Plateau, and in basins of the lower Yellow River and the middle-to-lower Yangtze River. The weakening of the Asian Summer Monsoon (ASM) since the mid-Holocene would have made Neolithic subsistence living unfavourable by decreasing the warmth and wetness in arid and semi-arid regions. However, it might not have been the sole factor that destroyed the Neolithic cultures in the vast territories of China ca. 4000 cal. yr BP. Environmental alterations in the major cultural territories of China reacted in response to precipitation anomalies caused by high variability of the ASM and the westerlies, which were modulated by centennial- to inter-annual- scale driving factors such as solar insolation, the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillations (ENSO). This most likely accounted for the nearly synchronous Chinese Neolithic cultural collapses. [ABSTRACT FROM AUTHOR]

• Hydrological variations in coastal plain are reconstructed by the magnetic method. • Greigite/pyrite bearing layers reflect waterlogged condition. • Hematite/goethite bearing layers reflect drier periods of soil formation. • Rapid hydroclimate fluctuations interrupt continuous Neolithic occupation. The Yaojiang Valley (YJV) on the southern Hangzhou Bay Plain, eastern China, was home to Neolithic cultures that date back to 8 ka. Reconstructions of ancient human cultures on the coastal plain in response to sea-level and hydroclimate changes have been well documented. However, centennial-resolution geological records are still lacking. Here, we present a combined approach of environmental (mineral) magnetism, geochemistry and diffuse reflectance spectroscopy (DRS) on a sediment core (YJ1503) in YJV to decipher the centennial hydroclimate oscillations of the coastal plain since early Holocene. Our results show that ferrimagnetic greigite and paramagnetic pyrite bearing layers correspond to periods of reducing condition that were caused by a higher water table while the presence of antiferromagnetic hematite/goethite corresponds to drier periods favorable for soil formation. Centennial scale fluctuations of magnetic mineralogy around the 8.2 ka cooling event and 7.5–6.6 cal ka BP reflect frequent and unstable environments, with limited Neolithic occupation. A strong drought event occurred around 6.0 cal ka BP, which was preceded by an extensive marine inundation event in the study area. This inundation event interrupted rice farming. Our study indicates that magnetic mineralogy can be used to reconstruct high-resolution hydrological processes in coastal plain and floodplain environments. These results are important to understand hydroclimate variation and Neolithic civilization response in environmentally sensitive areas. [ABSTRACT FROM AUTHOR]

The Ningfeng Plain on the South Hangzhou Bay in eastern China has long been recognized as a critical location for understanding the complex relationship between paleoenvironmental changes and human activities. Despite frequent hydrological alterations, the development of Neolithic cultures in this region offers a valuable opportunity to comprehend how ancient societies adapted to environmental transformations in the coastal zone. In this study, the authors analyzed a recently obtained sediment core (LJQ) from the Lujiaqiao archaeological site in order to reconstruct the coastal evolution of the study area over the Holocene. The foraminifera assemblage in core LJQ indicates that the study area was located in a coastal-littoral environment approximately 8.1–7.5 cal kyr BP, which gradually transitioned to an estuary receiving significant input from the open marine around 7.5–7.2 cal kyr BP. Magnetic parameters of the core then reveal the formation of a tidal brackish marsh during a period of marine regression around 7.2–5.5 cal kyr BP. The authors identified at least three episodes of elevated groundwater, likely caused by minor sea-level fluctuations. After 5.5 cal kyr BP, the influence of seawater diminished while freshwater influx increased, resulting in land formation and the development of a freshwater wetland. The Hemudu Culture first appeared in the hinterland of the Ningfeng Plain around 6.5–6.0 cal kyr BP. However, the instability of groundwater hydrological conditions would have hindered the development of Neolithic culture until the formation of the freshwater wetland at 5.5 cal kyr BP, yet the subsequent emmigration of the Liangzhu Culture was not related to any discernible environmental degradation. This study sheds new light on the complexity of the dynamic interplay between humans and their environment over time. [ABSTRACT FROM AUTHOR]

High-resolution climate variations since the last 4500 years in the monsoonal-arid transition zone of north-central China were revealed through the integration of proxies from sediment cores in the Lake Daihai basin. Human occupations in the lake basin deduced from archeological findings and historical literatures were then incorporated into the climate sequence to demonstrate the patterns of human responses to the climate changes, and the recent anthropogenic effects. It indicated that: (1) Climate dominated human-environment adaptations prevailed prior to ∼2700 cal yr BP. An amicable climate setting before ∼4100 cal yr BP would facilitate the growth of the Laohushan Culture (LC) in the lake basin, while a pronounced deterioration of water thermal condition after that had led to human exodus and the collapse of the LC. The reduced human activity in the lake basin indicated at ∼3800–3500 cal yr BP and a subsequent cultural blank at ∼3500–2700 cal yr BP, were both in response to the climate and lake level fluctuations during ∼3800–2800 cal yr BP. (2) Transition to a positive human adaptation was seen at ∼2700–1100 cal yr BP, represented by the exploitation of arable land for cultivation and animal husbandry as the lake contracted. (3) An increasing human presence that affected environmental processes became more severe over the last ∼1100 cal yr BP. This was basically due to the ongoing lake shore reclamation for cropping, and more recently heavy metals emissions from fossil fuel combustion and local industries. [ABSTRACT FROM AUTHOR]

The early Holocene environmental amelioration stimulated the trajectory of Neolithic farming cultures and specific geographic settings played a role in determining the nature of these cultures. Using microfossil evidence, the present study reveals that the fluctuations of the groundwater table substantially influenced rice domestication in the Dongting Lake area of the middle Yangtze River basin in the early Holocene. Our 14 C-dated sediment core taken from the Bashidang (BSD) Neolithic site contains evidence that the site was a floodplain prior to human occupation ca . 8600 years ago. Poaceae, which contained wild rice ( Oryza sp.) as indicated by combined pollen and phytolith evidence, and low counts of freshwater algae indicated a moist site condition. The area then gradually evolved into wetlands as the water table rose, in response to the increasing monsoon precipitation during the early Holocene. This favored rice domestication, assisted by firing and clearing, that continued to flourish for several hundred years. Finally, rice domestication declined during the late stage of the Pengtoushan culture, accompanied by evidence of the expansion of wetlands reflecting the effects of a rising groundwater table that had caused the cessation of rice farming at the Bashidang site after ca. 8000-7900 cal yr BP. This study shows that there are local effects at particular sites that may differ from the trend at the regional scale, necessitating a careful interpretation of the available evidence. [ABSTRACT FROM AUTHOR]

Abstract The influence of the mid-latitude westerlies (MLW) competing with the Asian summer monsoons (ASM) over the Tibetan Plateau (TP) remains a matter of discussion on how and to which extent both atmospheric systems have been controlling hydro-climate during the Holocene. Depleted oxygen isotopes in lake deposits were commonly interpreted in terms of enhanced summer monsoon moisture supply, implying a migration of the ASM deep into the interior of the plateau during Holocene periods. In order to test this relationship we used a high resolution oxygen isotope record (mean 20 yr resolution) in combination with carbonates and mineral phases, titanium flux, grain size and ostracod abundances derived from a 6.84 m long sediment core in the endorheic Kuhai Lake basin, north-eastern TP. The results confirm 1) continuous positive co-variance between enriched δ18O carb and total carbonates during the last 14 ka, indicative of dominant seasonal influence on multi-decadal to centennial scale isotopic signatures in lake water and respective carbonate precipitation, 2) negative co-variance between allochthonous sediment flux and δ18O carb (and carbonates) attributed to relative increase of flux rates during non-summer seasons, 3) correspondence of lake level variations with carbonate mineral phases and the occurrence/disappearance of ostracod assemblages, and 4) inverse relationships between isotopic signatures in ASM-dominated and MLW-controlled lake records across the TP. Enriched δ18O carb in Kuhai Lake sediments was primarily a result of high evaporation during the summer seasons, while ASM-related rainfall amount did not play an important role, likely counterbalanced by isotopic signatures from different water sources. Conversely, depleted δ18O carb was mainly attributed to water supply during non-summer seasons of colder temperatures and generally light isotopic signatures from MLW-derived sources. This finding may lead to a paradigm shift in such way that depleted δ18O in carbonates is primarily not the result from ASM-related rainfall as previously assumed. The reconstructed hydro-climatic history of Kuhai Lake indicates the dominance of westerly-derived climate during the Younger Dryas interval (12.8–11.5 ka) under very shallow pond-like conditions. Despite climate amelioration during the early Holocene (11.5–7.5 ka) hydrological conditions remained unstable with frequent alternations between dominance of summer and winter seasons. During the middle Holocene (7.5–5.5 ka) the lake experienced highest lake levels dominated by summer monsoon-related water supply, assigned to the Holocene hydro-climatic optimum. Frequent high-amplitude fluctuations afterwards (5.1–2.9 ka) refer to cooling/drying events under enhanced MLW influence accompanied by a strong lake level decline. The late Holocene (2.9 ka- Present) period experienced moderate isotopic variations and fluctuating lake levels in response to variable influence of summer- or winter-related hydro-climatic conditions. This seesaw-like pattern with amplitudes of >10‰ in δ18O carb resembles fluctuations in cave records and variations between air and seawater (Dole effect). High correspondence with cooling events derived from North Atlantic drift ice and meltwater discharge indicate close ties to northern hemispheric climate transmitted by the MLW across the TP. Highlights • Positive co-variance between δ18O carb and total carbonates reflect summer season impact. • Negative co-variance between allochthonous flux and δ18O carb points to non-summer impact. • Seasonal influence is identified by multi-decadal to centennial isotopic signatures. • Inverse relationships exist between isotopic signatures in ASM-dominated and MLW-controlled lake records across the TP. [ABSTRACT FROM AUTHOR]

The location of the Yellow River estuary controls the pattern of mud dispersal and therefore influences the ecology of China's marginal seas. However, little is known regarding the Holocene history of Yellow River avulsion. The Yangtze estuary, south of the Yellow River estuary, may provide some clues, as a large amount of Holocene sediments has accumulated in a major paleovalley in this area, incised during the Last Glacial Maximum (LGM). In this paper, we identify clay contributions from the Yellow River in the three Holocene cores (TZ, DY, and HM) of the Yangtze estuary using provenance analogues of clay geochemistry associated with the modern rivers, and reveal the history of Yellow River avulsion into the South Yellow Sea. The results show that clay geochemistry in the Holocene cores is similar to that of the Yangtze River, except for the period of ∼9.5–7.0 cal. kyr B.P. when it is represented by lower element contents more closely similar to those of Yellow River clays. Provenance end-member analysis shows 40%–60% clays of the Yangtze paleovalley was derived from the Yellow River during this period. These findings indicate that, at least, one channel of the Yellow River avulsed southward into the South Yellow Sea during the early to middle Holocene (∼9.5–7.0 cal. kyr B.P.). Fine-grained sediments from the Yellow River paleoestuary could be transported southward to the Yangtze paleovalley by enhanced marine energy during the early to middle Holocene. This study, not only, provides new evidence for Yellow River avulsion in the Holocene, but also sheds light on the impact of the Yellow River sediments on the depositional system along the coast of China, especially in the Yangtze delta. • Three Holocene cores of the Yangtze estuary are analyzed for clay geochemistry. • Geochemistry analogue with the modern rivers identifies clay provenance of cores. • Yellow River clay contributes high to the Yangtze estuary in early-middle Holocene. • Yellow River ever flowed into the South Yellow Sea during ∼9.5–7.0 cal. Kyr B.P. [ABSTRACT FROM AUTHOR]

The Holocene lake sediment records are critical indicators of past global change studies. This study attempts to reconstruct soil erosion rates (SERs) quantitatively based on lake sediment records from 35 lakes in China. Environmental sequences, e.g., precipitation, vegetation and human activity, were reconstructed and used to identify the dynamic processes of soil erosion based on the General Additive Model (GAM). The findings were as follows. First, drivers of soil erosion in lake basins in different sub-regions of China differed markedly due to the evolution of different monsoon systems and regional environments. Second, influenced by the evolution of different monsoon systems and regional environments, soil erosion of the Holocene showed different evolutionary processes in China. For example, SERs gradually increased in the northwestern arid zone and remained relatively stable in the monsoon zone until 2.0 ka (1 ka = 1000 calibrated a B.P.). Third, human activity played a more important role in soil erosion in all sub-regions during the Holocene. Human activities through vegetation/land-use change have led to rapid enhancement of soil erosion in the north, south, and southwest China since 2.0 ka, especially in the last 1000 years. This study contributes to our understanding of the evolution of soil erosion under different climate systems in China. • Holocene soil erosion rates were reconstructed quantitatively based on lake sediment records. • Drivers of soil erosion differed markedly due to the evolution of different monsoon systems in China. • Human activities have led to rapid enhancement of soil erosion since last 2000 years. [ABSTRACT FROM AUTHOR]

Subsidence of the ancient Zhejiang-Fujian Uplift (ZFU) is important to understand opening of the Chinese marginal seas and geomorphology of the east China coast. However, little was known about its subsidence history during the Quaternary. In this study we clarify three marine sedimentary layers constrained by luminescence (OSL) chronology in Ningde area of the southeast China coast, to reveal the regional subsidence evolution related to the ancient ZFU. The results show that three marine sedimentary layers above bedrock in Ningde area are formed during global sea-level highstands of MIS1, MIS3 and MIS5e, constrained by OSL datings of the three representative cores. Limited marine influence of MIS5e highstand indicated both by microfacies of the representative cores and by the paleo-shoreline outlined from 120 cores, implies that tectonic subsidence occurs here during the Late Quaternary. The offsets between the peak global sea level and the corrected paleo-shoreline elevations of MIS5e and MIS3 reveal that the average subsidence rate is ∼0.5 m/kyr since MIS5e and ∼ 0.8 m/kyr between MIS5e and MIS3 in Ningde area. This evidence suggests that the ancient ZFU possibly subsided rapidly since MIS5e and stabilized since MIS3. This study provides new insights into the subsidence history of the ancient ZFU and land-sea interaction in the tectonic subsidence region. • 120 cores are analyzed for transgression process in Ningde bay within the ancient ZF Uplift (ZFU). • 3 marine strata in the cores are recorded during sea-level highstands of MIS1, MIS3, MIS5e. • Limited marine influence of MIS5e highstand indicates a tectonic subsidence thereafter. • The ancient ZFU possibly subsided rapidly since MIS5e and stabilized since MIS3. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution of dinoflagellate cysts in the surface sediment of Sishili Bay, Yellow Sea, China, was studied, with the purpose of understanding the impact from nutrient enrichment and industrial pollution. Thirty-five dinoflagellate cyst taxa belonging to 15 genera and 3 unknown cysts were identified and quantified at 22 sampling sites. Autotrophic cysts (e.g., Spiniferites bentori var. truncata) and heterotrophic cysts (Brigantedinium sp.1 and Quinquecuspis concreta) dominated the sediment samples. The spatial distribution of cyst abundance showed a significant positive correlation with increased nutrients, but was negative to heavy metal pollution. The highest cyst abundance (with an average of 539cystsg−1 DW) occurred in Zone A, corresponding to nutrient enrichment caused by domestic sewage discharge. In contrast, the lowest cyst abundance (with an average of 131cystsg−1 DW) occurred in Zone E, impacted heavily by the industrial pollution. The abundance of autotrophic cysts decreased dramatically in Zone E compared with heterotrophic cysts and showed a sensitivity to industrial pollution. How heavy metals affect physiological mechanisms in autotrophic and heterotrophic cysts differentially is in need of in-depth study. [Copyright &y& Elsevier]

Well-known for its intensive land-sea interactions and the brilliant Neolithic Cultures, the South Hangzhou Bay (SHB) of eastern China has been the focus of early agricultural rise in adaptation to coastal environmental change. In this study, geological records from sediment cores were integrated with archaeological findings in SHB to establish the linkage between coastal geomorphological processes and Neolithic occupation since the Holocene. It showed that the Holocene geomorphological evolution of SHB was inherited from the south wing of the Late Pleistocene Qiantang incised valley. During ca.10,000–7600 cal yr BP, the paleo-incised valley was inundated and infilled by marine transgressive deposits, forming an estuary. Then coastal progradation started and gradually formed the periphery of SHB. Noticeably, freshwater wetlands firstly occurred at the apex of SHB, enabling foragers to settle down and fostering the Kuahuqiao Culture and rice exploitation (7800–7400 cal yr BP). In the semi-closed Yaojiang Valley (YJV), east of SHB, alluvial plain developed after 7800–7600 cal yr BP with coastal progradation, providing a habitat to favor the early arrivals and later became the centre of the Hemudu Culture (7000–5000 cal yr BP). Meanwhile, the Neolithic sites sporadically occurred off the YJV due to the existing inundation. The coastal progradation slowed down ca.5000–2500 cal yr BP, in association with decreased sedimentation rates. In the last 2500 years, the Shaoxing Plain and the Cixi Plain of SHB showed rapid progradation resulting from increasing sediment input and intensive reclamation. The diverse geomorphological processes of SHB were modulated by the combination of Holocene sea-level changes, sediment input and the inherited local topography. The Neolithic migrations were in phase with landscape transformations and gradual formation of coastal plain since the Mid-Holocene, facilitating the Neolithic subsistence transition from hunting-gathering to rice farming and fostering the brilliant Neolithic cultural sequence in SHB. [ABSTRACT FROM AUTHOR]

The well-14C–dated sediment core HM retrieved from the Yangtze River mouth was used to reconstruct the Holocene sedimentary–ecological complex of its incised valley. The complete Holocene sedimentary facies that were exclusively formed in the valley and evidenced by bio-geochemical measurement, showed the Latest Pleistocene fluvial facies to the Early-Holocene marine facies, and the Middle-Late Holocene deltaic facies. The established Holocene stratigraphic framework consists of 3 (I-III) infilling phases, of which phase I demonstrated the most rapidly infilling with coastal sediments into the valley (1.0 cm/yr), driven by the Early Holocene marine transgression. The remarkably low sedimentation rate of 0.1 cm/yr of phase II to the relatively low rate of 0.7 cm/yr of phase III occurred during the Middle-Late Holocene, reflecting sediments transported from river basin to directly fill in the valley along with deltaic depocenter shifted seawards as retrogressive processes. In addition, our microfossil (foraminifera and diatom) spectra displayed 3 distinctive biological stages with related sedimentary–ecological implications. During the Early Holocene, there were remarkably high numbers of diatom communities but few foraminifera, then followed a zone of less abundant microfossils between ca. 9.0–5.0 ka. After this time, richer foraminiferal communities appeared but diatoms were less abundant. The massive sediment infilling in the Early Holocene in the deeper (>60 m) incised valley would suppress benthic foraminiferal development, most likely due to anaerobic conditions in the lower water column. However, the flourishing diatom communities persisted in the brackish marine water associated with sea-level rise. The zone with fewer microfossils corresponded generally with the Middle Holocene sandy ridge formation at the core site, leading to poorer bio–preservation. After ca. 5.0 ka, foraminiferal communities gradually became adapted to the reduced salinity of the estuarine water associated with the deltaic progradation, though this appears not to have supported the diatom communities. • A paleo-sedimentary-ecological complex in the Yangtze incised valley was established. • The Holocene sediment strata recorded marine transgression and deltaic progradation. • Mid-Holocene sediment shortage from catchment was unable to feed the mid-outer valley. • Foraminifera-diatom assemblages were integrated to show valley's ecological setting. • Massive Early Holocene sedimentation caused valley bottom-water to be anaerobic. [ABSTRACT FROM AUTHOR]

South Hangzhou Bay (SHB) in eastern China is one of the regions where agriculture began in the early Holocene. To better understand how farming-based societies developed in this region, we examined pollen, charcoal, foraminifera and grain size information of a well-dated sediment core (YJ1503) in the Yaojiang Valley (YJV). Pollen assemblages show that before 8600 cal yr BP, Pinus , Quercus , Juglans and Pterocarya woodlands were dominant. During ca. 8600–8400 cal yr BP, abundant foraminifera suggest a transient marine incursion. Although the former woodland species re-established during 8400–7600 cal yr BP, freshwater algae and dinoflagellates indicate a transition to brackish environments. Two peaks of charcoal at around 8200 and 7800 cal yr BP, are possible early signs of human occupation that pre-dated the Hemudu Culture. After 7600 cal yr BP, an increase of salt-tolerant herbs including Chenopodiaceae, Cyperaceae and Poaceae (<35 μm) and a decrease of dinoflagellate and foraminifera assemblages, imply a reduction in saline influence. Freshwater wetlands established around 6600 cal yr BP as indicated by increasing Typha and diminishing Chenopodiaceae pollen. This coincided with a sharp decline in Pinus pollen, marked increases of Poaceae pollen and a rise in charcoal suggesting more activity of human communities. Rice cultivation is confirmed by archaeological findings from this interval, with two distinctive periods at ca. 6600–6300 and 5500–5200 cal yr BP. The initial coastal land development started as early as 7800–7600 cal yr BP in the YJV, which was concurrent with that happened at the apex of SHB where the Kuahuqiao Culture originated, but rice farming trajectory at these two places differed. In the Kuahuqiao area, low salinity coastal settings developed, freshened by the discharge of the Qiantang River,and this area would have been especially suitable for agriculture. In contrast, in the YJV, early rice cultivation was possibly hampered by longer episodes of brackish intrusion during time of lower discharge of the Yaojiang River until a freshwater environment prevailed after ca. 7000 cal yr BP. • Holocene environmental changes in the Yaojiang Valley was revealed. • Human presence occurred 1000 years before the Hemudu Culture. • Rice farming at Kuahuqiao and Yaojiang Valley started with varied wetland salinity. • Depressed rice farming occurred at 6300–5600 cal yr BP due to sea-level fluctuations. [ABSTRACT FROM AUTHOR]

This study establishes a Holocene sedimentation model for the incised valley of the Yangtze Delta based on key information taken from existing literature and new cores collected for this study. Distinctive sedimentary processes and mechanisms operating in the incised valley were revealed: 1) the significant role of a pre-Holocene incised valley on which the Holocene funnel-shaped bay was established in forming the topography of the present river mouth; 2) the backstepping migration of the depocenter in association with tidally-dominated sandy shoals developed in the Early-Middle Holocene, followed by fluvially-tidally dominated progradation during the Mid-Late Holocene; 3) the model of depocenter shift characterized by en-echelon sandy shoals in the incised valley, revealing stepwise migration from transgressive to retrogressive sedimentation in the Holocene, and 4) the dextral diversion of the river mouth controlled by strong tidal sedimentation in the valley and the Coriolis-driven tidal sedimentation off the valley throughout the Holocene. Our results further show that the sediment in the Holocene valley was characterized by an upward increase in foraminiferal abundance. This is a reversal of the usual pattern to the Holocene marine transgression, indicating a unique depositional setting in the valley, presumably due to higher turbidity and poor preservation caused by strong tidal currents. • Sedimentary model of the Holocene incised valley of the Yangtze delta • Holocene depocenter shift of the incised valley • Sediment-dynamics and formation of en-echelon shoals in the incised valley • Sedimentary analogue for the Holocene delta study in the world [ABSTRACT FROM AUTHOR]