Paleogeographic and paleoenvironmental evolution in northwestern Santa Cruz (Argentina), and its influence on human occupation dynamics during the late Pleistocene- early Holocene (original) (raw)
Related papers
Quaternary International, 2019
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.
Journal of Archaeological Science: Reports, 2022
Puesto Roberts 1-PR1-is an open-air archaeological site emplaced in a deflation sector that offer the possibility to investigate diverse lithic activities carried out by hunter-gatherers in central Patagonia Argentine. The site is located on the coast of Colhué Huapi lake, in Chubut province. In this work, we present a techno-morphological and intra-site spatial analysis of the lithic artifactual assemblage to discuss about stone tool production, lithic raw materials and to explore the activities that were carried out at the site. The action of post-depositional natural agents that may have caused the mobilization of materials and lithic refits are also analysed to bring insights into the spatial distribution of artifacts. The site is the result of the anthropogenic action, and the mobilization of certain materials produced mainly by the action of wind and water it was recognized. Different stages of knapping, lithic raw materials and lithic tools were recognized. Finally, PR1 is interpreted as an open-air campsite of short duration in its occupation on the late Holocene. Evidences of almost exclusive processing and consumption of carcass of Lama guanicoe were identified. This differs from sites recorded around the lake with chronologies similar to PR1, which show evidences of processing and consumption of fish. Therefore, PR1 contributes to the knowledge of the variability of human activities developed in this lacustrine landscape.
Comptes Rendus Palevol, 2006
A multi-proxy palaeoecological investigation including pollen, plant macrofossil, radiocarbon and sedimentological analyses, was performed on a small mountain lake in the Eastern Pyrenees. This has allowed the reconstruction of: (1) the vegetation history of the area based on five pollen diagrams and eight AMS 14 C dates and (2) the past lake-level changes, based on plant macrofossil, lithological and pollen analysis of two stratigraphical transects correlated by pollen analysis. The palaeolake may have appeared before the Younger Dryas; the lake-level was low and the vegetation dominated by cold steppic grasslands. The lake-level rose to its highest level during the Holocene in the Middle Atlantic (at ca. 5060€45 b.p.). Postglacial forests (Quercetum mixtum and Abieto-Fagetum) developed progressively in the lower part of the valley, while dense Pinus uncinata forests rapidly invaded the surroundings of the mire and remained the dominant local vegetation until present. The observed lowering of the lake levels during the Late Atlantic and the Subboreal (from 5060 € B.P. to 3590€40 b.p.) was related to the overgrowth of the mire. The first obvious indications of anthropogenic disturbances of the vegetation are recorded at the Atlantic/Subboreal boundary as a reduction in the forest component, which has accelerated during the last two millennia.
Journal of Paleolimnology, 2008
A high resolution multiproxy study (magnetic susceptibility, X-ray diffraction, XRF scanner, gray-colour values, Total Organic Carbon, Total Inorganic Carbon, Total Carbon and Total Biogenic Silica) of the sedimentary infill of Lago Chungará (northern Chilean Altiplano) was undertaken to unravel the environmental forcings controlling its evolution using a number of different multivariate statistical techniques. Redundancy analyses enabled us to identify the main provenance of the studied proxies whereas stratigraphically unconstrained cluster analyses allowed us to distinguish the “outsiders” as result of anomalous XRF scanner acquisitions. Principal Component Analysis (PCA) was employed to identify and isolate the main underlying environmental gradients that characterize the sedimentary infill of Lago Chungará. The first eigenvector of the PCA could be interpreted as an indicator of changes in the input of volcaniclastic material, whereas the second one would indicate changes in water availability. The chronological model of this sedimentary sequence was constructed using 17 AMS 14C and 1 238U/230Th dates in order to characterize the volcaniclastic input and the changes in water availability in the last 12,300 cal years BP. Comparison of the reconstructed volcaniclastic input of Lago Chungará with the dust particle record from the Nevado Sajama ice core suggested that the Parinacota volcano eruptions were the main source of dust during the mid and Late Holocene rather than the dry out lakes as has previously been pointed out. The comparison of the water availability reconstruction of Lago Chungará with three of the most detailed paleoenvironmental records of the region (Paco Cocha, Lake Titicaca and Salar Uyuni) showed an heterogeneous (and sometimes contradictory) temporal and spatial pattern distribution of moisture. Although the four reconstructions showed a good correlation, each lacustrine ecosystem responded differently to the moisture oscillations that affected this region. The variations in the paleoenvironmental records could be attributed to the dating uncertainities, lake size, lake morphology, catchment size and lacustrine ecosystem responses to the abrupt arid events.
Journal of Paleolimnology, 1997
A 27-m sequence of deposits from the Plio-Pleistocene Banyoles-Besalú lacustrine complex, at Tres Pins, N.-E. Spain, shows lithological, carbonate, pollen and spores, and ostracode-gastropod evidence of climatic and lake-level change. Upland pollen taxa from the lowermost zones 1, 3 and 5, show that the area was forested and indicate a progressive deterioration of the climate. Zone 2 (steppe vegetation) corresponds to a global glacial stage, with mild temperatures, if the comparison to modern analogues is valid. Only minor climate fluctuations occurred subsequently. Aquatic vegetation and micritic sediment facies show a pelagic environment during pollen zones 1 and 3 and a littoral one during pollen zone 5. A short-term lowering of the water level (sandy algal micrite and slightly brackish waters) occurred in zone 2, as a result of severe droughts. Subzone 2c records progressive recovery of the forest. The coarse lithology and the high carbonate content, however, continue to indicate shallow waters. The fluctuation marked by zone 4 (extensive marsh vegetation and spring waters) may be due to a lake-level decrease caused by karst activity, or by lower precipitation with only slight cooling, or more probably by a relative lake-level decrease caused by natural infilling. The sediment of pollen zone 4, a sandy algal micrite, indicates the development of a littoral bench at the core site. From pollen zone 4 to pollen zone 5 an evolution from lakeward to landward position occurred. In zone 2, droughts existed at least during the spring growing season, and probably also during the rest of the year. In subzone 2c, a shift to spring precipitation occurred. In contrast, during pollen zone 4, if there was a decrease in precipitation, it did not take place during the summer growing season.
Sedimentology
High-mountain lake records in semiarid foreland settings, such as the central Andes of Northwestern Argentina, are highly restricted and often deprived of well-preserved microstratigraphic information to analyze palaeoenvironmental changes and their causes, particularly for periods prior to the Last Glacial Maximum. Laguna La Salada Grande (23°S/65°W, 4063 metres above sea-level) is a closed shallow lake located at Cordillera Oriental, Northwestern Argentina with a unique depositional record, including geomorphic and stratigraphic evidence of palaeoenvironmental changes since the Late Pleistocene. In order to understand the depositional dynamics of this mountain lacustrine system at different timescales, limnogeological multiproxy analyses together with a radiocarbon and 210 Pb-based chronology were applied on massive and laminated sediments from La Salada Grande. Laminated deposits were further analyzed using novel sub-centimetric mineralogical, textural and geochemical automated methods (including a combination of micro-X-ray fluorescence and quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN â). Thick laminated microfacies at the beginning of the sequence record a deep and organic matter productive palaeolake prior to ca 34 ka (1 ka = 1000 years before 1950), that changed into a highly fluctuating shallower-palaeolake with frequent detrital influxes after ca 34 ka. Microstratigraphy of the coarser-grained detrital laminae between 31 ka and 25 ka reveals irregular and probably sub-centennial highenergy discharge events, pointing to convective atmospheric activity as the main trigger. After ca 21 ka the lake evolved to deeper water-level conditions resulting in fine-grained deposits with limited delivery of coarsegrained sediments, followed by an abrupt lake level drop and incision. The multi-millennial palaeoenvironmental reconstruction of La Salada Grande, 2585
Vegetational changes during the Holocene in Extra-Andean Patagonia, Santa Cruz Province, Argentina
Palaeogeography Palaeoclimatology Palaeoecology, 1998
Modern pollen-vegetation relationship was used in the interpretation of stratigraphical sequences from two archeological sites, La Martita cave (48°24′S, 69°15′W) and Alero Cárdenas (47°18′S, 70°26′W) located in Extra-Andean Patagonia in the Santa Cruz Province. The modern pollen assemblages are related to vegetation units that extend from the Andes toward the Atlantic coast, reflecting the increase of aridity from west to east. The more humid areas in the west are represented by grass steppe with Festuca pallescens; in those areas of intermediate humidity shrub steppe can be found with a conspicuous stratum of Stipa (S. speciosa, S. humilis and S. chrysophylla) and shrubs (Nardophyllum obtusifolium, Berberis heterophylla, Senecio filaginoides, Mulinum spinosum) and in the most arid areas scrub steppe expands with Nassauvia glomerulosa and cushion plants such as Azorella caespitosa, Accantholippia seriphiodes, Chuquiraga aurea, Brachyclados caespitosus. A vegetational and paleoclimatic history is presented based on comparison with modern analogs and with other palynological records from southern Patagonia. Prior to 8000 yr B.P. a grass steppe extended indicating relatively high precipitation under cold conditions. Between 8000 and 6000 yr B.P. an increase of shrub-steppe taxa, dominated by Asteraceae tubuliflorae would relate to an increase in temperature, while precipitation remained in the previous range of about 200 mm. The mid-Holocene (5000 yr B.P.) is reflected in the La Martita sequence by a short-term return of steppe taxa, primarily grasses. This steppe could indicate cold conditions similar to those of the early Holocene, or an increase in precipitation. After 4500 yr B.P. the vegetation is represented by grass-shrub steppe. After 3500 yr B.P. the Alero Cárdenas record shows a shrub steppe dominated by Asteraceae tubuliflorae. In records near the steppe-forest ecotone, at 47 and 50°S, the more extensive late Holocene forest suggests greater effective moisture, probably related to cooler temperatures. In Alero Cárdenas grasses increase and shrubs are irregularly present. In Altiplanicie Central steppe vegetation is analogous to the present vegetation. In the present century taxa indicative of disturbance are present (Rumex acetosella and Brassicaceae).
Holocene lacustrine deposition in the Atacama Altiplano: facies models, climate and tectonic forcing
Palaeogeography, Palaeoclimatology, Palaeoecology, 1999
We investigate the Holocene sedimentary infilling of two high-altitude (>4000 m a.s.l.) lacustrine basins in the subtropical regions of the Atacama Altiplano (Central Andes, northern Chile) that today contain permanent, shallow saline lakes: Laguna del Negro Francisco (27ºS) and Laguna Miscanti (23ºS). Laguna Miscanti was surveyed with multi-frequency, high-resolution seismic techniques and sediment cores were retrieved from offshore areas of both lakes. Because of the geological location of these lacustrine basins within the active Andean convergent margin, and the presence of present and past climatic gradients in the Altiplano, our detailed sedimentologic, mineralogic and geochemical study evaluates tectonic, volcanic, and climatic controls on lacustrine sedimentation in an arid environment. Both lakes originated by tectonic and volcanic activity during the Pleistocene. Tectonic control of basin dynamics was clearly exerted during the early stages: increased subsidence was responsible for alluvial fan activity in the Laguna Miscanti Basin prior to the establishment of the lake, and the Negro Francisco Basin changed from exorheic to endorheic. Hydrogeologic conditions needed to maintain the two perennial saline lakes are largely controlled by the basins' tectonic history. The evolution of Laguna del Negro Francisco comprises four successive stages: (1) perennial saline carbonate-sulfate lake;