DISTRIBUTION OF MAJOR ELEMENTS IN SURFACE SEDIMENTS OF BOHAI STRAIT AND ITS GEOLOGICAL SIGNIFICANCE

The major elements of surface sediments in the northern Bohai Strait, according to the analyzing results of the samples collected from 35 stations, mainly consist of SiO₂, Al₂O₃, Fe₂O₃, CaO, K₂O, Na₂O and MgO, which account for more than 94.85% of the total. SiO₂, Al₂O₃ and CaO dominate on average of 70.44%, 10.03% and 3.96%, respectively, suggesting the sediments of siliceous clasts and clays predominated by aluminosilicate minerals. SiO₂ is strongly negatively correlated with Mz, and their spatial distribution is consistent with coarse-grained sediments. Al₂O₃, Fe₂O₃, MgO, P₂O₅ and TiO₂ are similar in spatial distribution and consistent with that of fine-grained sediments. Moreover, there are obvious positive correlations among Al₂O₃, Fe₂O₃, MgO, Na₂O and TiO₂, indicating that their distribution is controlled by similar factors mentioned above. The correlation of major elements and R-factor analysis show that the major elements in the study area can be divided into three categories. The first category includes SiO₂, Al₂O₃, Fe₂O₃, MgO, MnO, P₂O₅, and TiO₂, representing terrigenous clastic deposits; the second category mainly consists of CaO and NaO, representing marine biogenous sediments; and the third category of K₂O may suggest the impact of marine authigenic sediment.