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In order to understand the paleogeographic evolution of Viedma Lake (252 masl) sedimentary sequences with glaciolacustrine and lacustrine strata between 307 masl and 266 masl and bathymetric fluctuations between 27 ka. and 2.4 ka. were identified. The paleoenvironmental interpretation of the stratigraphic profiles was carried out based on the analysis of facies and their associations. The oldest age was recorded at 301 masl (27 ka) and the youngest corresponds to 266 masl (2.4 ka). The record of 27 ka was compared with another dated record of the Tar-San Martin Lakes basin showing that Viedma – Tar-San Martín Lakes were formed at similar ages. Taking into account that the deposits of Bahía Túnel are located at 266 masl and that the level of the lake would be above this height, it is proposed that this lake level would have restricted the movement of hunter-gatherer populations along the coast and to the west. From 2.4 ka on a new space started to be available for these populations broadening the wintering grounds (≤400 masl). The chronology of the archaeological record found in this new space fits the proposed paleogeographic evolution. This paper complements the research on the evolution of lacustrine systems in the Patagonian Mountain range and broadens the discussion of human mobility in the Viedma Lake basin during the Holocene. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the variability of the stable carbon and nitrogen isotope composition of herbivores -guanaco and huemul-in southern Patagonia. The study area extends from the eastern slopes of the Andes to the Atlantic Coast between 47° and 49° S. The ultimate aim of the research was to generate an isotopic ecology with an adequate spatial resolution that allows the incorporation and development of stable isotope studies in discussions of the population dynamics of hunter-gatherers in continental Patagonia. This paper presents the δ13C and δ15N values of 159 guanaco and huemul specimens, both modern and archaeological. This space was divided into three areas: Western area, Central Plateau and Eastern Area. Isotopic variability within groups was analyzed using the SIBER, from which the isotopic niches of the different groups are compared. The results show a spatial pattern of isotopic variability in herbivores, i.e. lower δ13C and δ15N values associated with forest environments in the western end of the transect and higher values, especially δ15N, towards the east, with maximum values observed near the Atlantic coast. Our results support the stated expectations on herbivore stable isotope composition variability and its association with environmental variables in a longitudinal transect across the southern Argentinean Patagonia. [ABSTRACT FROM AUTHOR]

Abstract The main aim of this paper is to evaluate if certain processes that were documented in a specific area of Central-Southern Patagonia during the Late Holocene were also registered in a broader spatial scale. Previous investigations carried out in our study area located in Central-Western Santa Cruz province, Patagonia, have stated that climatic fluctuations during the Late Holocene (last 2500 years) were the cause of a reduction of hunter-gatherers' residential mobility. The new climatic conditions were characterized by important environmental droughts, which increased during the Mediaeval Climatic Anomaly, circa 900 years BP. This reduction in mobility resulted in concentrations of populations in low altitude basins and increased logistical and seasonal mobility, defined as a process of extensification. In this paper we take a broad spatial perspective to evaluate to what extent the low residential mobility identified in our research area had a correlation in a larger regional scale. Also we assess if this lead to a regional differentiation among hunter-gatherer populations, previous to European contact (450 years BP). In order to achieve these aims, we undertake a coarse grain analysis, using available data published on the composition and distribution of the archaeological record for Central-Southern Patagonia, an area of about 450.000 km2. Specifically, we consider evidence about technology, zooarchaeology, rock art, mortuary record and paleodietary studies. The analysis indicates that a reduced residential mobility could have occurred in certain areas of the study region, linked to the aforementioned climatic changes. On the issue of regional differentiation, the archaeological record highlights the complexity of this process. There are a variety of arguments both for and against the idea of a process of regionalization in Central-Southern Patagonia in the Late Holocene. We propose a process of differentiation of populations with low residential mobility which nonetheless remained connected through the circulation of goods, information and people. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, the analysis of a radiocarbon database of the North Coast of Santa Cruz (central Patagonia, Argentina), is presented. Dated archaeological samples were obtained from 56 different types of archaeological sites (open-air -residential sites and burials-, and also rock shelters). The objective of this paper is assessing the continuities and discontinuities in the chronological signal of the area and identifying tendencies along the Holocene. The database currently contains 75 radiocarbon dates falling between ca. 8000 and 300 BP. The radiocarbon data base provides information on the chronological, spatial and contextual variability of the archaeological record of North Coast of Santa Cruz. By means of different analysis of sum of probabilities, we present three different chronological moments of human use of the coast and intermediate zone can be identified. A first moment is represented by early evidence of settlement during Middle Holocene. A second moment corresponds to a hiatus between ca. 5800 and ca. 3900 BP without archaeological evidence. Finally, a third moment is where an increasing of chronological signal occurred, related to greater artifactual variability and an increase in the intensity of human settlement in the Patagonian region. The causes that could have influenced in the discontinuity of the chronological signal of the study area, and the characteristics of the different moments identified are discussed. [ABSTRACT FROM AUTHOR]

In this paper we focus on the regional/local scale of the archaeological record of the Central-West area of Chubut (Argentinean Patagonia) through the characterization of its regional taphonomy, considered from an archaeological perspective. We focus our research in the comparison of three different landscape situations: 1) a slope leading to highlands, 2) an azonal vegetal community (wetland or mallín ), and 3) a salt lake. Our main goal is to compare those situations, in order to determine the main taphonomic factors that regulate the archaeological material distribution in those locales. The ultimate goal is to address how past hunter–gatherers inhabited these landscapes. We depart from the assumption that distributions of artifacts are mainly explained by the action of post-depositional processes. To evaluate this assumption first we postulate a series of hypothesis and expectations for each locale, considering the main post-depositional agents present in them, and we evaluated if the patterns of material distributions can be explained by one or many of those processes. Only if explanation cannot be achieved by them, we recurred to human depositional activities. As a result we managed to explain most of the archaeological distributions in terms of post-depositional processes. Only in two cases we propose that human deposition occurred. [ABSTRACT FROM AUTHOR]

This paper summarizes and discusses the main results achieved over three decades of research on paleodemographic aspects of Late Holocene hunter-gatherers in Northwestern Santa Cruz (Argentina). Research has been guided by a model of regional settlement that proposes that, as a result of the progressive aridization process recorded in Patagonia during the Late Holocene, human groups would have reduced their residential mobility and concentrated their settlements in low altitude basins with water availability, such as Lake Cardiel and Lake Salitroso. Paleodemographic questions derived from the model relate to population regional continuity and dynamics and were tested using several lines of research at regional and local scales. The assessment of the chronological information and temporal trends of the archaeological record at the regional level allowed for a coarse grain paleodemographic approach, and acted as a mean to support hypotheses related to changes in mobility and land use strategies. Building on this, several lines of bioarchaeological evidence were used to address paleodemographic aspects of the model, including temporal, distributional, and compositional studies of the mortuary record, isotopic, morphometric and DNA analyses and the sex and age structure of the skeletal samples recovered in Lake Salitroso basin. Results point to a biological and cultural population continuity in the region during the Late Holocene. Also, a reduction in residential mobility would have favored a slight population growth of Lake Salitroso populations during the last millennium. [ABSTRACT FROM AUTHOR]