北极东西伯利亚陆架表层沉积物的岩石磁学特征及环境意义OA

As a key amplifier of global climate change,the Arctic is highly sensitive to climatic and environmental changes.Its sedimentary records provide important insights into high-latitude environmental processes and the evolution of the global climate system.This study presents the results of environmental magnetic analysis of surface sediments from 91 stations in the East Siberian Arctic Shelf.The mass-specific magnetic susceptibility(x)at low and high frequencies,frequency-dependent magnetic susceptibility(xfd),and anhysteretic remanent magnetization(ARM)were analyzed in combination with clay mineralogy and geochemical data,from which the variations in magnetic mineral assemblages and their environmental significance were investigated.Results reveal a pronounced spatial heterogeneity in low-frequency mass-specific magnetic susceptibility(xlf)of the sediments,based on which three distinct provinces were divided:two high susceptibility provinces of the eastern Laptev Sea and western Chukchi Sea,and a low susceptibility province of the central East Siberian Sea.The high magnetic susceptibility reflects primarily the input of terrigenous detritus rich in mafic minerals derived from basic igneous rocks in the source areas.In contrast,the low susceptibility province corresponds to the source rocks with weaker magnetic intensities,such as granites and metamorphic rocks.Values of xfd,ARM,and their ratio(xARM/x)are generally low in the estuarine and coastal areas,indicating the presence of coarser magnetic mineral grains.These parameters progressively increase towards the middle and outer shelf,signifying a dominance of fine-grained magnetic minerals.The observed variations reflect the combined effects of hydrodynamic changes and the resulting grain-size differentiation of sedimentary materials.In addition to fluvial input and ocean current processes,sea-ice dynamics also played a significant role in sediment transport and redistribution.The magnetic parameters of the East Siberian Shelf surface sediments integratively record multiple processes,including provenance and hydrodynamic conditions,thereby providing an important mean to understand the formation and evolution of the Arctic shelf sedimentary system.