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Major elements were studied for reconstruction of sediment provenance and paleoenvironment over the last 24 kaBP with the samples collected from Core PC-1 in the northern Okinawa Trough.In addition to major elements,grain size of 402 samples and planktonic foraminifer δ18O of 344 samples have been analyzed that leads to an average resolution at centennial scale.The study offers a new high resolution material for reconstructing the history and main control factors of the sediment input in the northern Okinawa Trough over the last 24 ka.In according to the variation in major element compositions,the core could be divided into three distinct depositional units,separated by two volcanic layers at 7.3 and 12.7 cal kaBP respectively.Both provenance discriminating plot and R-mode factor analysis indicate that vertical changes in major elements are mainly contributed by the nearby terrestrial materials,whereas the contribution from hydrothermal activity,marine biologic deposition,and volcanism are minor.In particular,the contribution of nearby terrestrial materials show an obvious change trend and can be well correlated with the sea level fluctuation and the evolution of the Tsushima Warm Current.It seems that paleoclimate renders no significant impact on the change in terrigenous sediment provenance.

Using XRD method,the clay minerals of two Quaternary cores F090815 and F100609 located in Parece Vela Basin,East Philippine Sea were studied in this article.The results show that there are some differences in mineral assemblage between the north and the south.In the southern core F090815 the most abundant content is smectite(50%),then illite(37%),and the lowest is kaolinite and chlorite(13%);however,in the northern core F100609 the most abundant content is illite(47%),then smectite(39%),and the lowest is kaolinite and chlorite(14%).According to contents and characteristic of clay minerals,both the cores F090815 and F100609 can be divided into four parts.According to assemblage characteristic,chemical index and crystallinity of clay minerals,we think that smectites were originated from submarine basalt alteration in the Mariana Trough;while illites were derived mainly from the west continent under strongly physical weathering probabeg associated with the tormation of loess in the East Asia continent,so were kaolinite and chlorite.

We here reconstruct the sedimentary evolution of South China Sea since Oligocene using samples from Ocean Drilling Program (ODP) site 1148 in the northern South China Sea based on a multi-proxy approach including monomineralic quartz oxygen isotope ratios or (delta(18) O), grain-size of isolated terrigenous materials, terrigenous mineral accumulation rate and SEM analysis of isolated quartz. It was found that the sedimentary evolution of South China Sea Basin could be divided into five stages: period of initial expansion (34 similar to 28. 5 Ma), period of intense tectonic activity (28. 5 similar to 23 Ma), period of reduced tectonic activity (23 similar to 16. 5 Ma), period of thermal subsidence ( 16. 5 similar to 3. 5 Ma) and period of Taiwan uplift (3. 5 Ma to present). Terrigenous mineral composition and oxygen isotope values of quartz altered significantly during 28. 5 similar to 23 Ma which was the period of provenance transition, corresponding to the most active period of South China Sea since Oligocene. Sediment source of ODP Site 1148 was mainly from Palawan during the early spreading period of South China Sea. With the extensive spreading of South China Sea, especially when the spreading axes of South China Sea jump to south during 25 similar to 23 Ma, Palawan continental block moved away constantly, and the changes in the regional geomorphic change caused by Tibetan Plateau uplift had not spread to Yunnan-Guizhou Plateau and South China, so Southern China mainland in the north had little or no impact on the study area, as a result, terrigenous mass accumulation rate was very low. Subsequently, owing to the rapid uplift of Qinghai-Tibet Plateau, rivers such as Pearl River developed gradually, so did the headward erosion, as a result, South China turned to be the main source of ODP site 1148, and South China Sea converted to distal deposition. With Taiwan Island uplift since 3. 5 Ma, a large amount of terrigenous sediments entered into the northern South China Sea, Taiwan turned to be the major source provenance of the study area. The hiatus of ODP site 1148 in the late Oligocene resulted from the lack of terrigenous material supply, sea level rise and relatively stronger currents during the source transformation.

Synthetic analyses on typical element ratio and source discrimination function were carried out for a sediment core with high sedimentary rate collected along the Tsushima Warm Current(TWC) main stream on the southwestern slope of Japan Sea,in order to trace the sediment provenance change of the study area in the Holocene.Data suggest that the Nakdong River of Korea and Changjiang of China are the main source of the studied sediments.Affected by the TWC strength evolution and sea level rise,their contributions changed with time.There are five stages.In the early Holocene(9.6-6.5 kaBP),especially during the two Melt Water Pulse(MWP) stages including MWP-1C(9.4-8.7 kaBP) and MWP-1D(7.8-7.4 kaBP),the contribution of these rivers was high.Their contribution became lower during 6.5-3.0 kaBP and 2.0-0.7 kaBP,corresponding to the temporally weakening of TWC in the northern East China Sea and southwestern Japan Sea.In 3.0-2.0 kaBP and 0.7-0 kaBP,TWC was strengthened and more fluvial materials from the Nakdong River and Changjiang River were deposited in the study area.

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 AMS(14)C 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 mu m, and the values of Sigma REE were 152.8-227.9 mu g/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.

Synthetic analyses on sedimentology and geochemistry of a sediment core with high deposition rate collected under the Tsushima Warm Current (TWC) axis on the southwestern slope of East/Japan Sea were carried out,in order to discuss the formation and evolution of TWC during the Holocene. Based on them,we got very similar results to those from paleoceanographical method in nearby areas. Thus,sedimentological and geochemical methods were offered for the future study on TWC evolution in the study area. Totally,there were five main evolution periods of TWC recorded in the study core. In the early Holocene,that is 9.6 kaBP,TWC began to weakly enter into the East/Japan Sea,together with the East China Sea Coast Water (ECSCW) enriched in nutrient matter,which led to the transfer of bottom environment from anoxic to oxic. At 6.5 kaBP,the modern current mode dominated by TWC in the southern East/Japan Sea finally formed,whereas the influence of ECSCW almost disappeared. After that,TWC obviously weakened. At 3.0 kaBP,TWC strengthened again to almost reach its present level,since then the circulation structure has been relatively stable,except for a weak depression of TWC during 2.0~0.7 kaBP.

Based upon analyses of grain-size, rare earth element (REE) compositions, elemental occurrence phases of REE, and U-series isotopic dating, the sediment characteristics and material sources of the study area were examined for the recently formed deep-sea clays in the eastern Philippine Sea. The analytical results are summarized as follows. (1) Low accumulation rate, poor sorting and roundness, and high contents of grains coarser than fine silt indicate relatively low sediment input, with localized material source without long distance transport. (2) The REE Contents are relatively high. Shale-normalized patterns of REE indicate weak enrichment in heavy REE (HREE), Ce-passive anomaly, and Eu-positive anomaly. (3) Elemental occurrence phases of REE between the sediments with and without crust are similar. REE mainly concentrate in residual phase and then in ferromanganese oxide phase. The light REE (LREE) enrichment, Ce-positive anomaly, and Eu-positive anomaly occur in residual phase. Ferromanganese oxide phase shows the characteristics of relatively high HREE content and Ce-passive anomaly. (4) There are differences in each above mentioned aspect between the sediments with and without ferromanganese crust. (5) Synthesizing the above characteristics and source discriminant analysis, the study sediments are deduced to mainly result from the alteration of local and nearby volcanic materials. Continental materials transported by wind and/or river (ocean) flows also have minor contributions.

Concentrations and carbon isotopic (14C, 13C) compositions of black carbon (BC) were measured for three sediment cores collected from the Changjiang River estuary and the shelf of the East China Sea. BC concentrations ranged from 0.02 to 0.14 mg/g (dry weight), and accounted for 5% to 26% of the sedimentary total organic carbon (TOC) pool. Among the three sediment cores collected at each site, sediment from the Changjiang River estuary had relatively high BC contents compared with the sediments from the East China Sea shelf, suggesting that the Changjiang River discharge played an important role in the delivery of BC to the coastal region. Radiocarbon measurements indicate that the ages of BC are in the range of 6910 to 12250 years old B.P. (before present), that is in general, 3700 to 9000 years older than the 14C ages of TOC in the sediments. These variable radiocarbon ages suggest that the BC preserved in the sediments was derived from the products of both biomass fire and fossil fuel combustion, as well as from ancient rock weathering. Based on an isotopic mass balance model, we calculated that fossil fuel combustion contributed most (60%–80%) of the BC preserved in these sediments and varied with depth and locations. The deposition and burial of this “slow-cycling” BC in the sediments of the East China Sea shelf represent a significant pool of carbon sink and could greatly influence carbon cycling in the region.

273 samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea (SCS) were analyzed for grain-size distributions using grain-size class vs. standard deviation method and end-member modeling algorithm (EMMA) in order to investigate the evolution of the East Asian monsoon since about 20 Ma. 10-19 μm/1.3-2.4 μm, the ratio of two grain-size populations with the highest variability through time was used to indicate East Asian winter monsoon intensity relative to summer monsoon. The mass accumulation rate of the coarsest end member EM1 (eolian), resulting from EMMA, can be used as a proxy of winter monsoon strength and Asian inland aridity, and the ratio of EM1/(EM2+EM3) as a proxy of winter monsoon intensity relative to summer monsoon. The combined proxies show that a profound enhancement of East Asian winter monsoon strength and winter monsoon intensity relative to summer monsoon occurred at about 8 Ma, and it is possible that the summer monsoon simultaneously intensified with winter monsoon at 3 Ma. Our results are well consistent with the previous studies in loess, eolian deposion in the Pacifc, radiolarians and planktonic foraminifera in the SCS. The phased uplift of the Himalaya-Tibetan Plateau may have played a significant role in strengthening the Asian monsoon at 8 Ma and 3 Ma.

From systemic research of microstructure, geochemistry, uranium-series and Be-10 isotope dating on a new-type deepwater ferromanganese crust from the East Philippine Sea, the paleoenvironment evolution of the target area since the terminal Late Miocene was recovered. The vertical section changes of microstructure and chemical composition are consistent in the studied crust, which indicate three major accretion periods and corresponding paleoenvironment evolution of the crust. The bottom crust zone was formed in the terminal Late Miocene (5.6 Ma) with loose microstructure, high detritus content and high growth rate. Reductions of mineral element content, accretion rate and positive Ce-anomaly degree at 4.6 Ma indicate temporal warming, which went against the crust accretion and finally formed an accretion gap in the terminal Middle Pliocene (2.8-2.7 Ma). The more active Antarctic bottom seawaters in the Late Pliocene (2.7 Ma) facilitated the fast transfer to the top pure crust zone. Hereafter, with the further apart of volcanic source and the keeping increase of eolian material (1.0 Ma), although surrounding conditions were still favorable, mineral element content still shows an obvious reducing trend. It thereby offers new carrier and data for the unclear paleoceanographic research of the target area since the terminal Late Miocene.

Manganese abnormity has been observed in the Holocene sediments of the mud area of Bohai Sea. On the basis of grain size, chemical composition, heavy mineral content and accelerator mass spectrometry (AMS) C-14 dating of foraminifer, relationships between manganese abnormity and sedimentation rates, material source, hydrodynamic conditions are probed. Manganese abnormity occurred during the Middle Holocene when sea level and sedimentation rates were higher than those at present. Sedimentary hiatus was not observed when material sources and hydrodynamic conditions were quite similar. Compared with the former period, the latter period showed a decrease in reduction environment and an inclination toward oxidation environment with high manganese content, whereas provenance and hydrodynamic conditions showed only a slight change. From the above observations, it can be concluded that correlation among manganese abnormity, material source, and hydrodynamic conditions is not obvious. Redox environment seems to be the key factor for manganese enrichment, which is mainly related to marine authigenic process.

A piston core Z14-6 was used in this study. The core, 896 cm long, was collected from eastern slope of the Okinawa Trough (27°07′N, 127°27′E, water depth 739m). The δ18O and δ13C values of the sediment bearing planktonic foraminiferaG. sacculifer andN. dutertrei were determined; and the abundance of volcanic glass was analyzed. The volcanic glass content high occurred in early stage of polar ice-sheet growth period, or the beginning of cold climate periods corresponding to Milankovitch cycles (Peak I, II and V are corresponding to the beginnings of oxygen isotopic stages 2, 4 and 6, and Peak III and IV are matching oxygen isotopic stage 5b–5d.). It might be possible that volcanic episodes and climate changes were responding to orbital forcing in the Okinawa Trough in late Quaternary. The δ18O difference betweenN. dutertrei andG. sacculifer shows no clear correlation to the volcanic glass content high, which suggests that the volcanic eruptions did not influence the structure of upper water column. However, the low δ13C difference betweenG. sacculifer andN. dutertrei is coeval with the volcanic glass high or sub-high content. This fact suggests that volcanic eruptions might influence the reduction in vertical nutritional gradient and carbon cycle process in upper water column. A possible mechanism is that huge quantity of ash and dust had weakened the light intensity, resulting in photosynthesis reduction, productivity decrease, and biological pumping.

Eolian dust is an important material source of marine sediment and heavy metals influencing marine environment and primary productivity. Although the eastern China Seas and their adjacent regions are downwind of East Asian dust sources and have potentially high atmospheric input, study on the eolian dus in these regions is limited. This study on the compositions of eolian dust indicated that dust concentration and particle sizes varied with seasons and meteorologic conditions, that mineral and chemical compositions have significant regional variation, and that high Fe content is one of the characteristics of eolian dust which was found to be a mixture of natural loess and/or soil and anthropogenic matter that contained fairly high S and heavy metals.

The radiogenic strontium (Sr) and neodymium (Nd) isotope compositions of the detrital fraction of surface and subsurface sediments have been determined to trace sediment provenance and contributions from Asian dust off the east coast of Luzon Islands in the western Philippine Sea. The Sr and Nd isotope compositions have been very homogenous near the east coast of the Luzon Islands during the latest Quaternary yielding relatively least radiogenic Sr (Sr-87/Sr-86 = 0.70453 to 0.70491) and more radiogenic Nd isotope compositions (epsilon(Nd)(0) = +5.3 to +5.5). These isotope compositions are similar to Luzon rocks and show that these sediments were mainly derived from the Luzon Islands. In contrast, the Sr and Nd isotope compositions of sediments on the Benham Rise and in the Philippine Basin are markedly different in that they are characterized by overall more variable and more radiogenic Sr isotope compositions (Sr-87/Sr-86 = 0.70452 to 0.70723) and less radiogenic Nd isotope compositions (epsilon(Nd)(0) = -5.3 to +2.4). The Sr isotope composition in the Huatung Basin is intermediate between those of the east coast of Luzon and Benham Rise, but shows the least radiogenic Nd isotope compositions. The data are consistent with a two end-member mixing relationship between Luzon volcanic rocks and eolian dust from the Asian continent, which is characterized by highly radiogenic Sr and unradiogenic Nd isotope compositions. The results show that Asian continental dust contributes about 10-50% of the detrital fraction of the sediments on Benham Rise in the western Philippine Sea, which offers the potentials to reconstruct the climatic evolution of eastern Asia from these sediments and compare this information to the records from the central and northern Pacific. Key Points Sr and Nd isotopic signatures of lithogenic fraction from the Philippine Sea Asian dust input in the western Philippine Sea Offer potentials for reconstructions of the climatic evolution of Asia

High resolution seismic profiles show two prominent late Quaternary sediment wedges on the outer and middle New Jersey continental shelf. An extensive wedge along the outermost shelf and upper slope, up to 50 m thick, appears to have been deposited on the Hudson Apron during an early melting of the late-Wisconsin Laurentide ice sheet; subsequent southward transport of this sediment occurred during sea level regression, still-stand, and transgression. A mid-shelf sediment wedge, which forms the Fortune shore, probably was deposited during a second melt event, 11 to 12 ka, as sea level was transgressing over the shelf.