Magnetic Characteristics of Aeolian Sand Sediments in Horqin Sandy Land, Northeastern China, and Its Paleoenvironmental Significance: A preliminary exploration

Abstract

In the Chinese Loess Plateau,magenetic susceptibility has been widely used as a proxy for the intensity of East Asian summer monsoon.It was generally accepted that pedogenic formation of ultrafine-grained magnetic minerals was the major contributor to the high magenetic susceptibility of the paleosols.However,few works have been done to investigate the mechanisms for the enhancement of magnetic susceptibility in the case of aeolian sand sediments in Horqin Sandy Land,northeastern China.Here detailed environmental magnetism and grain size studies of aeolian sand sediments taken from LHT section,which is located in the northeastern margin of the Horqin Sandy Land,are presented.Results show that the overall magnetic minerals content is low;the main magnetic minerals in the aeolian sand sediments are magnetite,with some haematite and goethite;the main magnetic grain sizes are SSD and SP.χARM/χlf and χARM/SIRM can indicate the relative strength of winter monsoon and summer monsoon.In terms of the whole section,magnetic grain size reflects the intensity of winter monsoon well,but in some strata,it was affected by summer monsson.Pedogenic superparamagnetic particles are the main cause of the magnetic susceptibility enhancement,and single domain particles play a subordinate role in the magnetic susceptibility enhancement during the optimum period of soil development.