Magnetic properties and chemical composition of the eolian sediments in southern Gurbantunggut Desert and its environment implications
The Gurbantunggut Desert is the second largest desert in China and is one of the major dust source areas in Central Asia.Determining the magnetic properties and chemical composition of eolian sediments in this desert have important implications for understanding the global climate change and dust material cycles.However,these issues remain highly uncertain.In this paper,we present the results of environmental magnetic,granulometric,geochemical analyses and OSL dating of GEB11 profile from southern Gurbantunggut Desert.The results indicate that the sedimentary magnetic properties are dominated by magnetite and it is mainly present PSD-MD state,the maghemite and haematite are also identified in the sediments of GEB11 profile.SiO2 and A12O3 take up a large part of chemical composition.Compared with the average composition of geochemical elements of the upper continental crust(UCC),all elements except SiO2 are depleted to a certain degree.Compared to the lower part(700-350cm),the sediments of the upper part(350-0cm)of GEB11 profile are characterized by higher magnetic mineral concentrations,coarser magnetic grain sizes,higher find sand proportion,lower SiO2 concentrationsand higher Al2O3,Fe2O3,CaO,MgO,Na2O,TiO2 concentrations.The physical weathering process and sedimentary sorting are the major factors influencing the magnetic properties and chemical composition of the sediments of GEB11 profile.The magnetic minerals and some metallic elements(e.g,Fe,Ti)are mainly concentrated within the fine sand that were transported and dispersed by wind.The upper part of this profile was formed during LIA and exhibited higher magnetic mineral concentrations,Fe and Ti concentrations and fine sand proportion which affected by the more intensive and frequent aeolian activity occurred during LIA.
magnetic propertieschemical compositionwind sortingGurbantunggut Desert
NETL
NSTL
万方数据
