Environmental magnetic characteristics of sediments of the western tropical Pacific: Response to the East Asian Winter Monsoon

The Western Pacific Warm Pool (WPWP) refers to a vast sea area located in the middle and west of the tropical Pacific Ocean (including the southern South China Sea and the Sulu Sea) with an average annual water temperature of over 28 °C. Covered by the ultra thick layer of warm surface water, with increasing prominence as a global heat source and site of water-vapor exchange, the WPWP plays an important role in driving the thermohaline circulation and regulating global climate change. The East Asian Winter Monsoon (EAWM), on the other hand, is one of the most active components of the global climate system. It can cause deep convection in tropical regions through cold waves, thereby strengthening convective activities and abnormal precipitation in the warm pool area. However, the historical interaction between WPWP and EAWM is still unclear. As aeolian dust carried by the EAWM usually contains large high-coercivity magnetic mineral particles, and these particles can cause fluctuations in environmental magnetic parameters, such as changing the mineralogy, concentration, grain size and morphology of magnetic minerals in sediments, one can assess the historical aeolian mineral inputs and EAWM intensity variations bv analvzine the chanees of environmental magnetic Darameters of Delaeic sediments in the WPWP. In this paper, we carried out environmental magnetic measurements on the BIO borehole sediments to reveal the response of the environmental magnetic characteristics of the WPWP sediments to the EAWM. We found the dominant magnetic minerals in the sediments were pseudo-single-domain (PSD) low-coercivity ferrimagnetic magnetite; and some high-coercivity magnetic minerals were also present. We also found the variabilities of high-coercive magnetic mineral content and relative content of fine-grained magnetite were highly correlated during the glacial and interglacial periods and sensitive to the EAWM intensity change: Both high-coercive magnetic mineral content and magnetic grain size increased during the glacial period and decreased during the interglacial period, in accordance with the strengthening and wakening of EAWM intensities during the respective periods. © 2022 Science Frontiers editorial department. All rights reserved.