Correspondence analysis and fuzzy C-means cluster methods were used to divide the stratigraphy of heavy mineral assemblages,and the sediment sources and depositional dynamics of the environment reconstructed.The assemblages were taken from marine sediments from the late Pleistocene to the Holocene in Core Q43 situated on the outer shelf of the East China Sea.Based on the variable boundaries of the mineral assemblage at 63 and 228 cmbsf (cm below sea floor),the core might have previously been divided into three sediment strata marked with units I,II and III,which would be consistent with the divided sediment stratum of the core using minor element geochemistry.The downcore distribution of heavy minerals divided the sedimentary sequence into three major units,which were further subdivided into four subunits.The interval between 0 and 63 cmbsf of the core (unit I),which spans the Holocene and the uppermost late Pleistocene,is characterized by a hornblende-epidote-pyroxene assemblage,and contains relatively a smaller amount of schistic mineral and authigenic pyrite.In comparison,the interval between 63 and 228 cmbsf (unit II),is representative of the Last Glacial Maximum (LGM),and features a hornblende-epidote-magnetite-ilmenite assemblage containing the highest concentrations of heavy minerals and opaque minerals.However,the interval between 228 and 309 cmbsf (unit III),which spans the subinterglacial period,is characterized by a hornblende-authigenic-pyrite-mica assemblage.Relative ratios of some heavy minerals can be used as tracers of clastic sediment sources.The lower part of the sediment core shows the highest magnetite/ilmenite ratio and relatively high hornblende/augite and hornblende/epidote ratios.The middle core shows the highest hornblende/augite and hornblende/epidote ratios,and the lowest magnetite/ilmenite ratio.The upper part exhibits a slightly higher magnetite/ilmenite ratio,and also the lowest hornblende/augite and hornblende/epidote ratios.The distribution of the mineral ratio is consistent with s
The multivariate statistical techniques, principal component analysis, Q-mode factor analysis, correspondence analysis and fuzzy C-means clustering were applied to analyzing the datasets of minor element concentrations in sediment samples of a core collected from the outer shelf of the East China Sea. According to the analysis results, the sediment core Q43 can be divided into three strata with different features in minor elements. The first stratum (unit Ⅰ) is characterized by higher concentrations of V, Cr, Cd and Sc, which are active and inactive elements. The second stratum (unit Ⅱ) is controlled by ultrastable elements V, Ti, Cr, Th, Sc, Pb, etc. The third stratum (unit Ⅲ) is dominated by Ni, Co, Ba, Rb and Mn, which are authigenic and volcanogenic elements. The geochemical features of the core Q43 show environmental changes in the depositional process from the Late Pleistocene to Holocene.
