Eastern Andean Patagonia (40º-51ºS) vegetation and climate variability during the Holocene related to southern westerlies fluctuations

SOTTILE, G. D.; MARCOS, M.A; BAMONTE, F.P; ECHEVERRÍA, M.E.; DE PORRAS, M.E; TONELLO, M.S. ; MANCINI, M. V.; BIANCHI, M.M.

Goa

Workshop; PAGES 2nd Young Scientists Meeting.; 2013

PAGES

The integration of the scarce eastern side of the Andes Patagonian peat, lake and caves records offer the opportunity to get a better understanding of a regional palaeoenvironmental synthesis. The selected fossil records implied in this study are located between 40-43°S in western (WNP), central (CNP) and eastern north of Patagonia (ENP) and between 49°-51°S in western (WSP) and central (CSP) south of Patagonia. Since the early Holocene northern and southern records shows similar patterns, displacing forest and grass steppe communities eastwards and showing high fire activity. This vegetation shifts may have been forced by weaker westerlies allowing humid air masses to reach eastward. During the middle Holocene WNP registered short humid periods inferred by eastern expansion of the forest communities and low fire activity meanwhile in CNP and ENP xeric steppe communities dominate with low fire activity suggesting arid conditions by an intensification of westerly belt. This westerlies behavior is inferred in WSP by the development of dense forest and arid shrubs steppes and low fire activity. Between 3000-2000yrs BP, north and south reconstructions suggest wetter conditions possibly associated to an equatorial displacement and weakening of the westerly belt. Since the 2000 to 500yrs BP there is a similar trend from wetter to arid conditions inferred by northern and southern sequences. After the medieval warm period (last 500yrs BP) the ENP shows palynological and charcoal evidences of wetter conditions than the previous period meanwhile the WSP presents short periods of wetter conditions inferred also by glaciological records.