Late Glacial pioneer vegetation and paleoenvironments in the Beagle Channel, Tierra del Fuego, southernmost Argentina: preliminary results

SAVORETTI, A., CANDEL, M.S., FERNÁNDEZ M., ; SUÁREZ G. M.; IGLESIAS A.; PONCE. J.F.

Salvador Bahia

Conferencia; X International Palynological Congress XIV International Organisation of Palaeobotany Conference; 2016

The study was performed in the basal section of the peat core between 10.37 and 9.94 m depth. This section consists of laminated silty-clay sediments and has been radiocarbon dated at the base 16,152 yr BP and the top as 13,298 yr BP. Nine samples from the base of the sequence, with a resolution-interval of 5 cm, were analyzed to determine the plant macrofossils, palynomorphs and diatoms content. For macrorests analysis, samples of 5 cm3 were disaggregated on a sieve (250 µm) and determinable rests were counted (at x20 magnification under stereo-zoom microscope). For determinations transmitted light microscope was used at 40x- 400x magnification. The samples for palynological analysis were processed following using standard techniques (Fægri and Iversen 1989). The palynomorphs were counted using a transmitted light microscope under a 400x to 1000x magnification. The diatoms analysis preparation process was carried out following the method described by Battarbee (1986) and mounted in Naphrax. Observation was made in a microscope using 1000 magnification. The sedimentological analysis were made with a Malvern Mastersizer 2000 Particle Size Analyzer with a resolution of 1 to 2 cm.The pioneer vegetation development in this recently deglaciated land mainly that included herbs (Poaceae and Cyperaceae), heath (Empetrum rubrum) and wet and rocky mosses (Isopterygiopsis, Plagiothecium). The low frequency and concentration values of Nothofagus pollen imply sources from distant forest. These preliminary data show the presence of a shallow lagoon environment close to recently deglaciated land, affected by local glacier meltwater discharge.