Magallanes maar fosil pollen record re-interpreted by using a pollen-climate claibration model. Terra Nostra

PRIETO A.R.; MANCINI, M.V,; QUINTANA F.A.; PAEZ M.M.; BORROMEI A.M.

Río Gallegos

Workshop; ICDP-Workshop PASADO. Potrok Aike Lake Sediment Archive Drilling Project; 2006

The only pollen record in the latitude of the Pali Aike Volcanic Field (southeastern Patagonia) that predate the LGM have come from a core drilled at dry Magallanes maar (52º 07´ S; 69º 16’ W) located in the Patagonian xeric grass steppe and is dated between 31,560 at 37 m and > 51,700 yr B.P. at 47 m (Corbella et al., 2000). A major problem with this record is the uncertain chronology, since they are close to the limit of the dating technique. Based on our experience with ongoing pollen studies, we re-interpreted the fossil sequence as either interglacial or interstadial based on the type of pollen assemblages. Eighty-six surface samples reflecting modern pollen dispersal from the Andes to the coast between 50º - 52º S and representing the Subantarctic forest, the humid and xeric grass steppes and the semi-desert (Quintana, et al., m.s) have been used to compare with the Magallanes maar fossil pollen assemblages. Although only twelve samples between 29 and 56 m from this sequence have enough pollen, this comparison allowed us to interpret that plant composition and climate were similar to humid and xeric grass steppe for different moments during the MIS3 – MIS4 (?), and to demonstrate the potential of the pollen – climate calibration model to be used as analogue in paleovegetational and paleoclimatic interpretations of the long sequence of Laguna Potrok Aike.