Marine magnetic signature of the Last Glacial Maximum and last deglaciation from the Southern Hemisphere mid-latitudes

Abstract

An environmental magnetic record is presented from piston core TAN0712-23, collected on the southern flank of Challenger Plateau at a water depth of 2817 m. Magnetic grain-size and concentration variations during the Last Glacial Maximum (LGM) are interpreted to reflect variations in terrestrial influx corresponding to glacial advance and stagnation events on millennial time-scales. The LGM signal between 25 and 23 ka demonstrates an antiphase relationship with Northern Hemisphere records implying that the bipolar seesaw was active during that period. The number and timing of features in TAN0712-23 suggest that LGM millennial scale climate fluctuations are strongly realized in the mid-latitudes, possibly due to amplification by regional forcing mechanisms. The onset of the deglacial magnetic signal, defined by a low concentration of magnetic minerals, is constrained at 18.6 cal ka BP by the radiocarbon age model and corresponds to southward migration of the Southern Hemisphere westerly wind system and Subtropical Front.