Environmental magnetic record of paleoclimate changes from the southwestern South Atlantic during the last glacial period: preliminary results.

Environmental magnetism is a powerful tool frequently used for paleoclimate and paleoceanographic studies because transport, deposition, and diagenetic reactions of magnetic minerals reflect environmental conditions. However, the environmental magnetic data in sediments can also be used as a proxy for paleoproductivity changes due to the predominance of biogenic magnetite in a noninteracting single-domain state. We conducted an environmental magnetic study of a deep-sea sediment core (42 to 5 ka) from the southwestern South American continental margin (29.22°S, 47.28°W, water depth 1514 m) to better constrain climatic and oceanographic, particularly ocean productivity variations. Environmental magnetic parameters (χ, ARM, SIRM, and χARM/SIRM) shows significant variations during marine isotope stages (MIS-1, MIS-2, and MIS-3). IRM acquisition curves, hysteresis loops, and FORC diagrams indicate the predominance of noninteracting magnetite particles within a narrow SD grain-size range. The contribution of magnetofossils suggests a different quantity of nutrient availability during the MIS stages.