Sedimentary Record And Environmental Implications Of Northern Sea Of Japan For The Past27ka

Marginal sea is both the bridge between the ocean and the land, and the main areaof the material and energy exchange with the land, which plays a very important rolein continental climate development. The Sea of Japan is the Pacific Northwest’slargest and most typical semi-enclosed marginal sea. Rebuilding the sedimentaryrecord of the sea of Japan has important implications for understanding the evolutionof climate and sea-level fluctuations of itself, the Pacific and the global, at the sametime, the sediments have great reference value in analyzing its relationship with theclimate system and environmental characteristics between East Asia regions,understanding the evolution of the ancient environment in East Asia during the specialclimatic events and key geological period, and projecting of climate change andenvironmental trends that may occur in the future evolution.This paper selected the core located on the circulation channel of deep water inSea of Japan to be the object of study，integrated sediment grain size parameters,environmental magnetism, relative abundances of chemical elements and colorreflectance and other indicators, through the analysis and comparison ofrelevant documents and materials, to classify the sedimentary strata and analyze theevolutionary history of sedimentary environment in this region. The results show,sediment is mainly silt, that most content is more than60%,sand and clay content arerelatively small. However, due to the large span of deposition age and more cold andwarm climate changes,the particle size of the has larger changes in the verticalfloating. By the results of particle size analysis to identify the average particle sizeand content of sensitive component (22.1-420.4μm) to be the substitute index of thestudy area sedimentary environments in northern part of Sea of Japan. Combined withrecords and field observations, the core is divided into eight parts. Through theparameter analysis of magnetic susceptibility anisotropy, all of process of depositionremains a relatively primitive state deposition, since the formation was not affected by obviously disturbance. Through vertical trends of samples susceptibility found thathas better correlation with the content changes of coarse particles(sand), showingmore coarse particles, the greater the magnetic susceptibility characteristics are.Besides combining color reflectance data, dark ferromagnetic mineral in coarsesediments is a key factor in causing changes in magnetic susceptibility. By curvevarying the relative content of Ti is drawn the changes in the deposition processterrigenous input. The relative content of Fe has a good correlation between the sizeparameters, magnetic susceptibility parameters, and color reflectance. The relativecontent of Co and Zn and other transition metal elements preliminary reflectsedimentary environments redox conditions. The relative content of Ca and Sr can beused as a sign of non-terrigenous, thus indirectly infers the strength of depositionalenvironment oxidation-reduction conditions and hydrodynamic. The AMS14C datingof96cm and346cm at the borehole results that both these locations age were8910±25a.BP, and26900±90a.BP.Through the analysis of columnar sample sedimentary record, combined with theexisting data, the results preliminary infer global heating and abrupt climate changeevents since the last glaciation in the northern part of the Sea of Japan having theresponse. This paper conducts a preliminary inversion for deposited climate ofresearch area and obtains the following results:The sediments may be deposited since27,000years at the depth of346cm of thedrilling. The deposition process respectively goes through D-O event—H2event（24.1Ka BP Heinrich event）—D-O event—the Last Glacial Maximum—D-Oevent—H1event（16.8Ka BP Heinrich event）—Poring-Aller d warm period—theYounger Dryas event—8Ka BP cold event—the Holocene Megathermal.