Diatom assemblage changes in lacustrine sediments from Isla de los Estados, southernmost South America, in response to shifts in the southwesterly wind belt during the last deglaciation

Abstract

Isla de los Estados (54°45 0 S, 63°10 0 -64°4 6 0 W) lies east of the main island of Tierra del Fuego and is the southeastern-most point in Argentina. Because of its geographic position near the latitudes of the Southern Hemisphere Westerlies and the strong influence of the Antarctic Circumpolar Current (ACC), the area is suitable for paleoecological and paleoclimate research. The island is not far north of the Subantarctic Front, which limits the northern boundary of the ACC. Paleoenvironmental study in this geographic location can shed light on past changes in atmospheric and marine circulation patterns. Diatom analysis of the lower part of a sediment sequence from Laguna Cascada (54°45 0 51.3 00 S, 64°20 0 20.07 00 W) enabled inference of changing lake conditions between 16 and 11.1 cal ka BP. Between 16 and 14.4 cal ka BP fragilarioid diatom species, often a pioneer group, dominated the record. Their presence shows seasonally open-water conditions from the onset of sedimentation. In zone II (14.4-12.8 cal ka BP), the dominance of planktonic/tychoplanktonic Aulacoseira spp. might represent longer ice-free periods and windier conditions, which would have kept this heavy species suspended in the water column. This period corresponds to the Antarctic Cold Reversal, when the Southern Hemisphere Westerlies were possibly centered on the latitudes of Tierra del Fuego, resulting in windy and wet conditions. Zone III (12.8-11.1 cal ka BP) is dominated by benthic diatom taxa that are mainly associated with peat and wetland M. Ferna ´ndez (&)

Shallow depositional basins as potential archives of palaeoenvironmental changes in southwestern Greenland over the last 800 years

“…In addition to association with grain size, the Sr/Rb ratio is believed to reflect the relative contribution of physical and chemical weathering to detrital input, since Sr is more easily released from primary minerals and leached from the catchment than Rb (Fernández et al . 2013; Adamson et al . 2019).…”

“…2004; Fernández et al . 2013). Together with high abundances of the small benthic fragilaroids ( Fragilariforma virescens (Ralfs) Williams and Round, Fragilaria capucina var.…”

Lake-Level Changes and Their Paleo-Climatic Implications at the MIS12 Lower Paleolithic (Middle Pleistocene) Site Marathousa 1, Greece

“…Rubidium (Rb) is a conservative element mainly associated with clay minerals where it often substitutes for K (Jin et al, 2006;Kylander et al, 2011;Heymann et al, 2013). In a humid climate, the content of Rb tends to be elevated due to a high precipitation and a subsequent increase of erosion and terrestrial input (Fernández et al, 2013;Heymann et al, 2013).…”

The contribution of tephra constituents during biogenic silica determination: implications for soil and paleoecological studies

“…changes in productivity, climate, precipitation and nutrient supply). In lacustrine sediment cores, BSi content can range from the detection limit (0.01 wt %) to > 70 wt % SiO 2 (Frings et al, 2014a). The downcore variations in BSi through time vary from as little as 2 wt % SiO 2 (Adams and Finkelstein, 2010;Ampel et al, 2008) to a high of 10-40 wt % SiO 2 (Johnson et al, 2011;Prokopenko et al, 2006;Van der Putten et al, 2015) and depends on several interacting factors such as mineral matter or organic matter accumulation, diatom productivity and preservation/dissolution processes.…”