Preliminary paleomagnetic results of a terminal pleistocene/holocene record from northeastern Buenos Aires province (Argentina)

Abstract

Paleomagnetic data from the Lomas del Mirador (34° 39.29’ S, 58° 32.17’ W) sedimentary section in northeastern Buenos Aires province (Argentina) comprises 149 oriented samples that record a significant but gentle gradual change in the geomagnetic field at the terminal Pleistocene and Holocene. Based on rock magnetic and detrital remanence experiments, the deposit seems to be a good recorder of the past geomagnetic field behavior. The characteristic remanent magnetization (ChRM), determined by progressive AF demagnetization, shows that the sections registered normal and inter­mediate polarities during the terminal Pleistocene/Holocene. The PSV is cha­racterized by a large variation with ~ 80° difference in inclination in both sections and a significant but gentle westward shift in the declination in the upper part. A similar trend was observed in the paleomagnetic record re­gis­tered in other sections from northeastern Argentina. This remarkably large PSV, especially the inclination record, became a reliable chronostra­ti­gra­phical marker for latest Pleistocene/Holocene sedimentary deposits in north­eastern Buenos Aires. VGPs resemble those registered during terminal Pleis­to­cene and Holocene in the southern cone of South America. Palaeomagnetic poles for the sections other contemporaneous sites from northeastern Ar­gen­tina fall some ~ 5–15° away from the Earth’s rotation’s axis.