Hematite and goethite content in the dust deposition from the eastern islands of the yangtze river delta and its paleoclimatic significance

The dust deposition in Shengshan Island, East China Sea is an important aeolian archive, which can pro¬vide information on the East China monsoon during the Late Quaternary. In this paper, the sodium citrate-sodium bi¬carbonate-sodium dithionite (CBD) method was used to remove free iron, different proportions of hematite and goe¬thite were added to the matrix, and the standard was established by the multiple linear regression method. The results show that the hematite content in Shengshan Island is 0.18%-0.40% with an average value of 0.31%, and the content of goethite is 0.77%-1.19% with an average value of 1.11%. According to the content characteristics of hematite and goethite combined with geochemical and environmental magnetic parameters, we conclude that the monsoon precipi¬tation decreased from 54 ka to 46 ka, and the monsoon precipitation increased from 46 ka to 39 ka. High values at 46±4 ka may indicate a cold event.