Last Deglaciation Climatic Fluctuation Record by the Palaeo-Daocheng Ice Cap, Southeastern Qinghai-Tibetan Plateau

The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau（QTP） is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides（TCN） 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap（pDIC）, southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B？lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.

Evolution of Palaeoenvironment of the South Yellow Sea Since the Last Deglaciation

The sediments in core YS01 recovered from the South Yellow Sea mud deposit zone contain abundant benthic foraminifera,particularly shallow continental shelf species,but rare of planktonic foraminifera.The benthic foraminifera are dominated by stenohaline cold shallow-water species and euryhaline brackish-water species.In this paper,the palaeoenvironmental changes were discussed based on the grain-size compositions and benthic foraminiferal assemblages.Six different benthic foraminiferal assemblages were discriminated by species analysis from the foraminiferal fauna.According to AMS14C dating data in core YS01,we identified four main stages of marine environmental changes since the last deglaciation:a near-shore depositional stage(13.1–9.5 kyr B.P.),a transitional stage from near-shore deposition to shallow-sea deposition(9.5–5.6 kyr B.P.),a high sea level stage with shallow-sea deposition(5.6–2.9 kyr B.P.),and a stable shallow-sea depositional stage(2.9 kyr B.P.to the present).

Rare earth element geochemistry in the inner shelf of the East China Sea and its implication to sediment provenances

Gravity core EC2005, located in the mud wedge off the Zhejiang-Fujian coast in the inner shelf of the East China Sea （ECS）, was analyzed for its lithology, grain size, rare earth elements （REE） and AMS14C dating. Results revealed high-resolution paleoenvironmental evolution and multiple switches of sediment provenances in the inner shelf of ECS. The lithology, grain size and REE concentrations of sediments varied significantly down the core. Mean grain size ranged from 8 to 121 μm, and the values of ΣREE were 152.8-227.9 μg/g. The chondrite- and shale-normalized REE patterns indicated their similarity to the terrigenous sediments in the study area. Between 17.3-12.3 ka BP the sediments in the inner shelf of ECS were mainly originated from local drainage basins. The source then gradually switched to the Yangtze River between 12.3 and 9.8 ka BP. Since about 10-9.8 ka BP, the sediments in the study area were dominantly derived from the Yangtze River. The continuous rising of sea level and formation of coastal current along the inner shelf played a key role in the switches of sediment provenances.