Paleogeographic reconstruction of the Tar – San Martín lacustrine system during late Pleistocene to early Holocene: Landscape availability and hunter-gatherer circulation (Santa Cruz, Argentina)

Abstract

This paper presents the paleogeographic reconstructions of flooded areas of the Tar-San Martín lacustrine system during the late Pleistocene-Holocene. The dimensions of lacustrine and glaciolacustrine levels of this basin are higher than the current levels of the lakes. The organic matter of lake levels recorded on stratigraphic profiles was described, sampled and dated using AMS, while other paleobathymetric indicators were also identified (height of the fan-delta apex and paleo-coast levels). Deriving out of the reconstruction of flooded areas it was established that the lake system was formed before 28 ka ago and would have reached its maximum expansion around 12 ka ago. The first hunter-gatherer occupation of the basin (11 ka) corresponds to the period of initial contraction of the lake system and the composition of the current configuration of the coastlines. This scenario would have allowed the exploration of western areas and the gradual incorporation of the forest to the action range of hunter-gatherer populations. Similarly, the levels of lakes Tar and San Martín would not have hindered the movement of human populations through the steppe throughout the Holocene.

The evolution of the Patagonian Ice Sheet from 35 ka to the Present Day (PATICE)

“…26A). Palaeolake Tar likely formed by this time (Horta et al, 2019). However, prior to 35 ka, the ice extent in this valley may have been greater, though the timing is difficult to ascertain.…”

“…We map the extent of ice-dammed palaeolakes at each timeslice. The extent of the palaeolakes is constrained by published geomorphology and chronology (Bell, 2009;Bendle et al, 2017b;Caldenius, 1932;García et al, 2014;García et al, 2019;Glasser et al, 2016b;Hein et al, 2010;Horta et al, 2019;Martin et al, 2019;Martinod et al, 2016;Thorndycraft et al, 2019a;Turner et al, 2005). The ASTER GDEM dataset was used to interpolate lake levels between mapped shorelines or other geomorphological datapoints.…”

“…The Bella Vista/Ultima Esperanza lobe is discussed in the Gran Campo Nevado section. During ice sheet recession, ice-dammed lakes formed in the over-deepenings currently occupied by the present-day lakes (García et al, 2014;Glasser et al, 2011b;Horta et al, 2019;Ponce et al, 2018;Sagredo et al, 2011;Strelin et al, 2011) (Fig. 24).…”

“…Solari et al, 2012), although the col location is uncertain. Palaeolake Tar has formed in front of the O'Higgins/San Martin Lobe (Horta et al, 2019). At 20 ka, the extent of many outlet lobes is uncertain.…”

“…Fig.24. A. Glaciers, lakes and rivers of the Southern Patagonian Icefield (48°-52°S), and published chronology (ka) and geomorphology(Ackert et al, 2008;Ashworth et al, 1991;Casassa et al, 1997;Dowdeswell et al, 2016a;Fogwill and Kubik, 2005;García et al, 2012;García et al, 2018;Glasser et al, 2011b;Horta et al, 2019;Kaplan et al, 2016;Lastras and Dowdeswell, 2016;Marden and Clapperton, 1995;Masiokas et al, 2008;Mercer, 1965Mercer, , 1968Mercer, , 1976Moreno et al, 2009;Sagredo et al, 2011;Strelin et al, 2014;Wenzens, 1999Wenzens, , 2005Wenzens, , 2006. Mean 10 Be ages of moraines are shown in pink crosses.…”