Geochemical Records Of Clay-grain Size Sediments And Their Implications For The Provenance And Sedimentary Environments In Bohai Sea And Yellow Sea

We live on earth，as we all know，human survival and development is closelyrelated with the Earth.As a matter of a fact，the issue that human global developmenthave become increasingly prominent。In order to live better，we should put emphasison the environmental research in modern society.Ocean is a major part of the Earth and one of the core content of global changeresearch.It plays a decisive role in the Earth’s climate。Seabed sediments，whichrecord geological history，marine chemistry，physical process，global climate change，as well as changes in environmental history， allow us get a comprehensiveunderstanding of the global environment and climate change law.The Yangtze River and the Yellow River，the two typical rivers in China，bring inlarge amounts of sediment to the eastern shelf of the sea every year.In order toinvestigate the provenance evolution，spatial and temporal distribution，as well as itsenvironmental implications of the eastern shelf sea，identifying the provenance of theYellow River and the Yangtze River has been becoming fairly prevalent.The claymineral components，the sensitive size of the marine sediment，play a sensable andreliable role in tracing the source area，provenance input of the sediments andsedimentary.In this paper，we have done the geochemical research of the clay sediments fromsurface samples that got from Bohai Sea，as well as the granularity，clay minerals，deposition rate，and the geochemical analysis of sediments in clay grain size from B03core samples that obtained from Yellow Sea，respectively.The conclusions we gotcurrently are as follows: (1) Grain size characteristics of core B03sediment indicate that the core isrelatively homogeneous and sedimentary recorded continuously，grains are sand，siltand clay which are <0.25mm，but are mainly gray，gray-brown clayey silt，and sandysilt accounts for a small part; kurtosis，skewness，and sorting coefficient are overallstable，and sorting coefficient trend is contrary to the previous two，which showssorting poorly; sediments are deposited continuously and fine granularity，the size ofwhich vary small from top to bottom，indicating that the core was grown in a lowenergy and stable sedimentary environment where hydrodynamic conditions arerelatively weak.(2) B03clay mineral assemblages show the core are mainly illite，it also containsa large number of smectite (11.0%-15.2%)，triangular diagram illustrates the core aremainly consist of Yellow River sediments.From the coupling between clay mineralsand the main and trace elements of clay grain sediments，B03core clay grainsediments are characterized by the calcium-rich smectite，illite-rich potassium，whilein the core vertical variation of constant elements we concluded that the value of CaOand K2O are divided into upper and lower levels based on the90cm boundary，the topvalue is significantly higher than that of the bottom，indicating that the source and theenvironment have undergone a significant change.(3) The geochemical variation in90cm of CaO，NaO，K2O，ΣREE etc.Verticalchart analyzed from core B03indicates that there was a significant change inprovenance around the90cm boundary.Based on the210Pb dating data of core B03，the depositional age of90cm boundary is163a，the Yellow River was diverted fromHuang Hai Ruhai to the Bohai Sea in1855，the time of which match that of the90cm boundaries of the B03，suggesting that differences around the90cm boundary inB03were most likely caused by the Yellow River diversion.After the Yellow Riverdiversion，the coastal currents in Shandong Peninsula carried a lot of Yellow Riversubstances and were deposited rapidly here，so sediment above the90cm had a greataffinity with the Yellow River，while90cm below the sediment mainly accepted theShandong Peninsula and submarine bedrock erosion products. (4) Through the geochemical analysis of sediments in clay grain size，lord，traceelements characteristics show that B23Rock was located in the northern Yellow Sea，and probably accepted materials of the Korean Peninsula and Liaodong Peninsula，itscharacteristic of high Ca is not obvious; while the B43core was located in the BohaiSea，the main source of input material is terrigenous，and its major elementsproperties are consistent with the substances in the Yellow River due to the Bohai Seais a nearly closed inland sea which surrounded by the continent.V，Ni，Co and otherelements which indicate weathering effects in B43are higher than those in the YellowRiver，stating that they experienced some weathering in sedimentary transport，thevalue of Zn，Cu and other heavy metals is also significantly greater than the YellowRiver，stating that they have suffered contamination more or less; the highest Cu，Zncontents in B03indicate that it was probably contaminated in the transport processesfrom the mouth of the Yellow River to the Shandong Peninsula; REE characteristicsdisplay HL-2，HL-3and HK1are consistent with the Yellow River substance，othersamples were higher than Yellow River substance in content of rare earth elements，high levels of rare earth elements illustrate that they possibly were affected by othersource material in the handling and deposition process.