A Preliminary Exploration Of Relative Paleointensity Record Of Core JLT11A Sediments In Jilantai Salt Lake

One significant advance in the study of the geomagnetic field has been the use of the remanent magnetization of sediments to study the evolution of the dipole field,in particular of its intensity.Records of absolute paleointensity are sparse,discrete and may be imprecisely dated compared to records of relative paleointensity.Lake sediments offer the advantages of high sedimentation rates(hence potentially high stratigraphic resolution),wide distribution and accessibility,and thus are also being increasingly used for relative paleointensity research.Jilantai Salt Lake belongs to continental arid climate and sensitive to the climate change.It's difficult to rebuild the climate change of this region for the limit of accurate age data.With the increasing amount of data from different regions,stacks of relative paleointensity(RPI)curves are becoming the global standard for paleointensity comparison.Continuous paleomagnetic and mineral magnetic measurement were conducted with the lake sediments of core JLT11A.The aim is to construct a relative paleointensity record with a high resolution chronology,which can potentially be used as a future dating tool for high-resolution paleoclimatic studies.We got three conclusions here.(1)The vectors tend to decay linearly to the origin after the AF level of 20 mT,indicating the successful removal of a soft component of magnetization.NRM 20mT was chosen as ThRM.Most of the MAD values less than 10° indicate that demagnetization results are reliable.(2)The Rock Magnetism results indicate that the core preserve a stable remanent magnetization and the magnetic mineralogy is dominated by coarse Single-domain(SD)and pseudo-single domain(PSD)magnetite in a narrow range of grain sizes,which meeting the criteria for relative paleointensity analyses.(3)NRM20mT/ARM was chosen as the RPI curve of core JLT11A,and compared with Sint-200and NAPIS to establish the RPI age model.To make sure the reliability of the age model,the deposition rate was also compared with the other climate records in this region.The stratigraphic position of the four intervals of reversed polarity,Gothenburg?Lachamp?Norweg.-Greenland Sea and Blake excursion,supports the reliability of the age model.