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The INQUA Dunes Atlas project has developed a global digital database of chronological information for periods of inland or continental sand dune accumulation and stabilization. The database comprises information on the site location (including coordinates), dune type, and stratigraphic context, pertinent analytical information (e.g. luminescence procedures), and literature citations to the original data source. This paper discusses the background to the project, the concept and structure of the chronologic database that forms its core, and gives some examples of the scope of the database and ways in which it can contribute to greater understanding of the spatial and temporal variability in dune development. Fil: Lancaster, Nicholas. Desert Research Institut; Estados Unidos Fil: Wolfe, Stephen. Canadian Geological Survey; Canadá Fil: Thomas, David. University of Oxford; Reino Unido Fil: Bristow, Charlie. Birkbeck University; Reino Unido Fil: Bubenzer, Olaf. Universitat Zu Köln; Alemania Fil: Burrough, Sallie. University of Oxford; Reino Unido Fil: Duller, Geoff. Aberystwyth University; Reino Unido Fil: Halfen, Alan. University of Kansas; Estados Unidos Fil: Hesse, Paul. Macquarie University; Australia Fil: Roskin, Joel. University of Haifa; Israel Fil: Singhvi, Ashok. Physical Research Laboratory; India Fil: Tsoar, Haim. Ben Gurion University of The Negev; Israel Fil: Tripaldi, Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentina Fil: Yang, Xiaoping. Chinese Academy of Sciences; República de China Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

El objetivo de la presente investigación fue determinar la relación existente entre el fortalecimiento de la creatividad con las manualidades y su influencia en la formación de los estudiantes de Artes Industriales. El desarrollo de las manualidades se circunscribe a la ejecución de ocho técnicas, que los estudiantes estudian a fin de que apliquen en cada técnica la innovación y la creatividad; es decir el desarrollo de cada técnica permite a los estudiantes tengan la oportunidad de estimular su propia creatividad al elaborar sus propios proyectos. La muestra fue intencionada conformada por los estudiantes de las promociones 2017 ,2018 y 2019 del programa de estudios de Artes Industriales, haciendo un total de 20 estudiantes varones y mujeres Se demostró la que el fortalecimiento de la creatividad con manualidades influye en la formación de los estudiantes de Artes Industriales de la UNE.

The Utracán paleo-dune field (La Pampa Province, Argentina, southern South America) was examined by remote sensing, morphometric analyses and field surveys as a case study of complex megadunes of inland deserts. The paleo-dune field is within the Utracán-Argentino valley, one of the transverse valleys of La Pampa Province excavated into a regional structural plain. Similar paleo-dune fields occur within these valleys. Utracán dunes are mostly stabilized by grasses, deeply disturbed by cattle grazing and agriculture. The paleo-dune field is formed by complex parabolic megadunes with superimposed dunes. Parabolic megadunes present lengths of trailing arms of 3.3–12.9 km, widths between them of 2–2.9 km and heights of 7–38 m. The position of the dune noses at the northeastern tip of the bedform and measured SW-NE orientation of arms indicate a mean transport direction to azimuth 68.2°. Above the parabolic arms, and isolated in the paleo-dune field, there are compound blowout dunes (clusters of several blowouts forming a larger bedform). They show the depositional lobes to the NE, with a measured mean transport direction to azimuth 58.1°. The SW-NE longitudinal length varies between 324 and 1302 m and the NW-SE transverse length between 114 and 622 m. Other parabolic arms show low (

Stable carbon isotopes (δ13C) and C/N ratios in bulk sediment organic matter were used as indicators of C3 and C4 vegetation functional types in a ca. 40-kyr, predominantly alluvial sequence from Arroyo La Estacada (33.5°S, 69°W), in the arid Andean piedmont of central Argentina. Although this sediment sequence has the potential to contribute to the knowledge of past vegetation dynamics through its fossil pollen content, previous palynological studies provided scant information, constrained to a few time windows, because of poor pollen preservation. Stable isotope results for the total organic carbon fraction from three lithostratigraphic sections that span the past 40 kyr show shifts in δ13C values associated with changing contributions from C3 and C4 plants, suggesting this proxy can detect changes in these photosynthetic pathways, representative of Patagonian (and/or stream-margin macrophytes) and Monte phytogeographic units, respectively. Climate and local factors, such as water availability in the basin, are inferred to be the main drivers of vegetation dynamics. The C/N ratios in a few samples show that organic matter sources are algae and/or phytoplankton, not solely C3 or C4 vascular plants. The δ13C record from Arroyo La Estacada is an example of how isotope geochemistry has overcome difficulties with pollen analysis and provided a reliable tool to investigate past vegetation changes in regions where C3 and C4 are differentially distributed. Isotope values during part of the Marine Isotope Stage 3 (MIS 3) and the middle Holocene are attributed to C3 local floodplain plants, with a little or no contribution from regional terrestrial (Patagonian) vegetation. Late Pleistocene–Holocene palaeosols have a clear C4 signal of terrestrial dominance, representative of Monte plants, thus, carbon isotope values constrain the early times of MIS 1, particularly where the Pleistocene–Holocene transition occurs. A mixture of C3 and C4 values during the last 3–4 kyr is indicative of environmental conditions that prevail in the region today. Fil: Rojo, Leandro David. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Provincia de Mendoza. Municipalidad de San Rafael. Museo de Historia Natural de San Rafael; Argentina Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: García, Adriana. University Of Wollongong; Australia Fil: Chivas, Allan R.. University Of Wollongong; Australia. University of Adelaide; Australia

The Cañadón Amarillo area in northwestern Patagonia (Mendoza Province, Argentina) presents a rich archaeological record contained within thick successions of fine-grained deposits with well-constrained chronological and stratigraphic resolution. Geomorphological, sedimentological, and archaeological analysis of three archaeological localities, constrained by radiocarbon ages, was conducted to reconstruct site formation processes and depositional variability in an exposed, dryland setting. The archaeological sites are located in the Cañadón Amarillo area between the southern margin of the volcanic Payunia Plateau and the Colorado River, in an area of ephemeral streams and eolian sand sheets. The archaeological remains are preferentially contained in fine to very fine sand to silty sand deposits associated with the ephemeral streams. Low-energy fluvial deposition related to overbank flows, and eolian aggradation associated with coppice dunes, sand shadows, and unrippled and partially vegetated mantles have favored preservation of in situ archaeological materials. Our investigations provide insight into site formation processes in exposed settings within the semiarid parts of northwestern Patagonia and extend the local record of human occupation to ∼7300 14C yr B.P. Fil: Tripaldi, Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Neme, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Gil, Adolfo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Giardina, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Salgán, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina

The Quequén Salado river basin has been the focus of several contributions since the first decades of the XX century, namely dealing with the general geological features of the deposits and with the vertebrate remains. In this paper, the Neogene geological history documented by the Quequén Salado river exposures is reconstructed by means of stratigraphic, sedimentological and paleomagnetic studies along with the paleontological analysis of vertebrate remains. The study area is a crucial setting not only to better understand the evolution of the southern Pampas basin during the late Miocene-early Pliocene interval, but also to test the validity of the biochronologic and biostratigraphic schemes, especially the “Irenense”. A geological model for the Quequén Salado river valley is proposed: a case of downcutting and headward erosion that contributes with a coherent interpretation to explain the spatial distribution of facies and fossil taxa: the younger in the distal sector of the Quequén Salado middle basin and the older in the lower basin. The sedimentary record is believed to represent the distal reaches of a distributary fluvial system that drained from the Ventania ranges. The stratigraphic section of Paso del Indio Rico results a key stratigraphic site to fully understand the stratigraphic nature of the boundary between the Miocene and the Pliocene (the Huayquerian and Montehermosan stages/ages). In this sense, two stratigraphically superposed range zones have been recognized in the area: Xenodontomys ellipticus Range Zone (latest Miocene-early Pliocene; late Huayquerian), and Eumysops laeviplicatus Range Zone (early Pliocene; Montehermosan). Taking into account the available geological and paleontological evidences, the “Irenense” would not represent a valid biostratigraphic unit, since, according to the geological model here proposed, it would be represented by elements of the Xenodontomys ellipticus Range Zone in the lower QS basin and by elements of the Eumysops laeviplicatus Range Zone in the middle QS basin. Fil: Beilinson, Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Gasparini, Germán Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina Fil: Tomassini, Rodrigo Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Deschamps, Cecilia Marcela. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina Fil: Barendregt, R.W.. University of Lethbridge; Canadá Fil: Rabassa, Jorge Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Occurrences of high arsenic (As) in sediments and groundwaters were investigated in the Claromecó fluvial basin, southern Pampean plain, Argentina. This investigation includes sedimentology, mineralogy, and hydrogeochemistry of the Neogene and Quaternary aquifers to determine possible sources and transport mechanisms for As in the Claromecó basin. Characterization of the sediments revealed homogeneous mineralogy in both Neogene highlands and Quaternary floodplains with abundant plagioclase, volcanic glass shards (VGS), K-feldspar, quartz, clay minerals and minor concentrations of clinopyroxenes, orthopyroxenes, hornblende, epidote, Fe-(oxy)hydroxides and fluorapatite. The sedimentary As concentrations ranged between 2.8 and 31 mg kg−1 in both aquifers. The average total dissolved As (dissolved AsT) concentrations was 47.2 ± 30.8 μg L−1 (15.3–110 μg L−1) in groundwater in Neogene aquifer (GW1), while it was 97.1 ± 30.6 μg L−1 (45–144 μg L−1) in Quaternary floodplain aquifer (GW2), with all samples exceeding WHO's guideline for dissolved AsT in safe drinking water of 10 μg L−1. Some GW1 (33%) and all GW2 samples contained high levels of fluoride (F−) ranging from 0.6 to 2.6 mg L−1 (1.37 ± 0.59 mg L−1) in GW1 and 2 to 5 mg L−1 (3.2 ± 0.9 mg L−1) in GW2 which also exceeded WHO's guideline for F− in safe drinking water of 1.5 mg L−1. Elevated concentrations of Na+, Cl− and SO4 2− in the Quaternary flood plain groundwater (GW2) could indicated some degree of sea water mixing as well as some contribution from inland processes (e.g. high evapotranspiration rates, long residence time and soil-water interactions). Dissolution of As bearing VGS or Fe-(oxy)hydroxides, alkaline desorption or competitive desorption with HCO3 – from Fe-(oxy)hydroxides appear to be dominating processes of As mobilization, while desorption from fluorapatite elevate dissolved F− levels. This study provides valuable insights on As mobilization processes in Neogene and near coast Quaternary floodplain aquifer. Fil: Sosa, Numa Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Kulkarni, Harshad V.. Kansas State University; Estados Unidos. University Of Texas At San Antonio.; Estados Unidos Fil: Datta, Saugata. Kansas State University; Estados Unidos. University Of Texas At San Antonio.; Estados Unidos Fil: Beilinson, Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Porfido, Carlo. Università degli Studi di Bari; Italia Fil: Spagnuolo, Matteo. Università degli Studi di Bari; Italia Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Surber, James. Kansas State University; Estados Unidos

The extra-Andean Pampean plain of central Argentina shows a complex evolution history. Three basins were identified in the subsurface (Salado, Macachín and Laboulaye) generated during the opening of the South Atlantic Ocean in the Mesozoic with a continuous subsidence history from the Oligocene to the Quaternary. The purpose of this contribution is to analyze the Cenozoic sedimentary filling of the Pampean plain basins with the goal of interpreting the tectonic evolution and understand the subsidence history. The study was based on the correlation and integration of subsurface data. Isopach maps were constructed from boreholes logs for each stratigraphic unit to infer depositional patterns, temporal and spatial thickness distributions, and possible depocenter migrations. The data was integrated in order to analyze the subsidence history of the basins and evaluate the potential mechanisms of post-rift tectonic reactivation of the passive margin. The Cenozoic sedimentary record was divided into three intervals for purposes of analysis with contrasting distribution and mechanisms. The late Oligocene-early Miocene (∼27-19 My) interval started before and continued during the earliest stage of the Andean orogeny; the second interval (early Miocene-middle Miocene 19- 15 My) that coexisted with the initial stages of Andean uplift and the third interval (middle Miocene-Quaternary, 15 My-Quaternary) developed during the last stages of the Andean orogeny. The subsidence during the late Oligocene-early Miocene was geographically restricted to the pre-existent basins, so an extensional reactivation of the Mesozoic depocenters is proposed. It is considered to be associated with an Oligocene generalized extension responsible for basin development before the beginning of the Andean orogeny, which later shifted into transpressional conditions. The early Miocene sedimentation (19-15 My) is here interpreted as the result of subsidence during the beginning of the Andean orogeny due to a less common but lengthy process that may lead to foreland rifting or transtension in the three analyzed basins. The middle Miocene-Quaternary (15 My-Present) interval is characterized by a blanket-like subsidence resulting in monotonous thicknesses with reduced-scale accumulation, both in the basins and over the relative highs. This sedimentation is interpreted as the result of accumulation in an extensive distal foreland basin with the foredeep located in the Alvear basin, the forebulge in the Pampa Central block, and the backbulge in the Laboulaye, Macachín and Salado basins. Located far east from the Andean tectonic loads, this distal foreland basin cannot be solely explained by short-wave subsidence patterns. Thus, dynamic subsidence is here proposed as an additional mechanism. Fil: Folguera, Alicia. Secretaria de Industria y Mineria. Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

Inland dune systems of South America occur in a variety of environmental settings under different climatic conditions, from humid–subhumid to semiarid–arid. This contribution provides the state of the art on dune research of inland systems east of the Andes. Tropical northern (∼10°N–∼10°S), including the dune fields of Llanos del Orinoco and the Amazonian basin, are mainly formed from parabolic, blowout (or deflation basins) and linear dunes, developed on river floodplains. Aeolian activity was reported to occur near the late Pleistocene–Holocene boundary in Llanos del Orinoco, over the last ∼17 ka in the Branco river basin and ∼32.6 ka in the Negro river basin, both in the Amazonian region. In general, the attributed aeolian origin is controversial, the morphology difficult to determine, and the chronology still extremely limited and rather debatable in some cases. The southern tropical region (∼10°S–∼22°S) includes aeolian systems situated across the extensive lowlands of the Gran Chaco and those located in fluvial basins related to the cratonic Brazilian shield (São Francisco River, Pantanal and Mato Grosso). The oldest barchanoid–barchan ridges at the Gran Chaco were dated ∼36–33 ka and subsequent aeolian sand accumulation occurred at ∼18 ka, ∼14–12 ka, ∼10–9 ka and mid to late Holocene times. Parabolic dunes at the São Francisco River floodplain show an oldest episode generated between ∼28 and ∼11 ka, followed by eolian activity during the early to mid-Holocene. No chronological data is available for the linear and lunette dunes described at the Pantanal. Linear ridges were distinguished in the upper Paraná River (Mato Grosso) with associated sand accumulation at different intervals of the Holocene. The last reviewed region is the Andean Piedmont and western Pampas, at subtropical eastern South America, comprising a large variety of dune morphologies (barchan–barchanoid, linear, parabolic, transverse and lunette dunes, deflation basins, and sand sheets). Luminescence ages suggest the occurrence of aeolian activity intervals during late glacial times and the Holocene. The general understanding on the dynamic of South American dune systems is hampered by the paucity of chronological information and the representativeness of some dune records. Whether they reflect local or regional environmental conditions is still a matter of discussion in several areas that need further studies. Fil: Tripaldi, Alfonsina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Universidad Nacional de la Pampa. Facultad de Cs.exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de la Pampa; Argentina

Cuyo is a heterogeneous environmental region with two major domains, the Western mountain ranges and the Eastern lowlands. The variety of environmental conditions is clearly reflected by the soils. Entisols are regionally dominant resulting from the balance of prevalent arid conditions together with coarse texture parent materials, and the relative young age (late Holocene) of the parent material. Humification and melanization are the dominant pedogenetic processes. Aridisols, the second most dominant soil order, reflect a long-lasting and complex evolution with evidences of calcification, gypsification and clay illuviation. Paleoenvironmental conditions (fossil criopedoturbation) are documented in the mountain domain, indicative of past glacial conditions as well as a wider extension of periglacial conditions (present and fossil Gelisols). Mollisols and Histosols are also present with a limited areal extension at some piedmont settings. The irrigated agricultural oasis of Cuyo, deeply transformed by human activities, has generated new conditions for soil development both in their physico-chemical properties (OM, P, N, texture and alkalinity) and the parent material. Negative colateral effects as salinization, piping, rill and gully erosion are now active. Consequently, soil management, particularly in the fragile ecotonal ambiance of Cuyo, is a major priority in land environmental programmes as elsewhere.

Microvertebrates are a major component of many assemblages recovered from the Quaternary of the Argentine Pampas. The main goal of this paper is to analyse the taphonomic history of a Holocene microfossil bonebed, recovered from the infilling of a burrow. Evidences suggest the plains vizcacha Lagostomus maximus as the putative producer of the burrow. The assemblage includes individuals belonging to different taxa of mammals (marsupials and rodents) and reptiles (snakes). Taphonomic features suggest that the accumulation inside the burrow was related to flooding processes in the plain. The burrow was a natural trap that favoured the accumulation and preservation of remains corresponding to individuals from different sources. According to the taphonomic evidence, some individuals (Lagostomus maximus, Lestodelphys halli and Serpentes indet.) died inside the burrow, whereas others (Microcavia australis, Reithrodon auritus and Ctenomys sp.) died outside the burrow, and after a time of being exposed on the surface their remains were transported by surface run-offs into the burrow. The record of Lestodelphys halli and Serpentes indet. in the burrow produced by Lagostomus maximus could be related to a circumstantial use. Mammal burrows are a significant taphonomic mode for the late Cenozoic of the Argentine Pampas., Centro de Investigaciones Geológicas, Comisión de Investigaciones Científicas de la provincia de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas

Impact cratering can destroy life from local to global scales and result in sudden turnovers of dominant genera and/or species. Here we report that it can also preserve components of the local biology present at the time of impact. We have investigated floral matter encapsulated within Cenozoic Era impact glasses produced by separate bolide impacts into the loessoid sediments of Argentina that occurred between 9.2 Ma (Miocene) and 6 ka (Holocene). The encapsulation preserved not only macro-scale morphological biosignatures such as vascular bundles, veins, phytoliths, and papillae, but also structures down to the cellular level. In the best-preserved samples we also found evidence for organic matter. While fossilization typically occurs over an extended time period as minerals slowly replace organic matter and the host rock lithifies under pressure, the process documented here is instantaneous. Preservation of morphological and chemical biosignatures in impact events can provide snapshots of the ecology in environments that do not otherwise promote a diverse fossil record. We suggest that this would provide a new strategy for identifying signs of possible early life on ancient Mars, where similar target conditions once existed. Fil: Schultz, P. H.. University Brown; Estados Unidos Fil: Harris, R. Scott. Georgia Department of Transportation. Office of Materials and Testing; Estados Unidos Fil: Clemett, S. J.. Jacobs Technology Inc.; Estados Unidos Fil: Thomas Keprta, K. L.. Jacobs Technology Inc.; Estados Unidos Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa; Argentina

One of these paleosols developed affecting the topmost part of likely Late Glacial aeolian deposits aggraded into a floodplain environment by the end of the Late Pleistocene. The paleosol shows variable grade of development along the arroyo outcrops. Organic matter humification, carbonate accumulation and redox processes were the dominant processes associated with paleosol formation. By the early Holocene, when the formation of the paleosol ended, renewed alluvial aggradation and high magnitude flooding events affected the arroyo's floodplain environment. Accordignly, a period of relative landscape stability in the Arroyo La Estacada basin is inferred from the paleosol developed by the LP–EH transition in response to the climatic conditions in the Andes cordillera piedmont after the Late Glacial arid conditions. The analyzed Late Glacial–Holocene alluvial record of the Andean piedmont constitutes a suitable record of the LP–EH climatic transition in the extra-Andean region of Argentina. It is in agreement with regional paleoclimatic evidence along the southern tip of the South American continent, where other pedosedimentary sequences record similar late Quaternary paleoenvironmental changes over both fluvial and interfluvial areas. Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

The piedmont of Cordillera Frontal between c. 33° and 34°S (Mendoza, Argentina) is a highly populated area deeply modified by human activities, known as Valle de Uco. It is situated within the borderland region of the geological provinces of Cordillera Frontal and Cuyo basin. The landscape is dominantly composed of both erosional and depositional landforms made of fluvio-aeolian deposits fractured and folded by tectonic processes together with some landforms of volcanic origin. Alluvial fans, related to several aggradational cycles of Quaternary age, are the most remarkable geomorphological units. Several tectonic features are present giving rise to conspicuous morphological features. Some of the streams are structurally controlled by faults while several drainage anomalies that indicate active tectonic processes have been identified. The Late Quaternary alluvial sequences, dominantly comprising sandy and silty deposits of volcaniclastic composition and secondarily metamorphic rocks, represent the fine-grained sedimentary facies of the fluvial systems accumulated in a distal fan environment. The alluvial deposits have been incised by several episodes of erosion since Pleistocene time. The Andes Cordillera and the piedmont of Mendoza province (Argentina) are an active tectonic area characterized by a complex geological setting that determines a heterogeneous landscape. Of particular environmental and human significance is the piedmont of Cordillera Frontal between c. 33° and 34°S. Known as Valle de Uco, it is a highly populated area deeply modified by human activities and constitutes one of the three man-made agricultural oases of Mendoza province (Fig. 1). Consequently, the reconstruction of the piedmont evolution and the understanding of the processes involved are essential to evaluate possible environmental responses under the present climatic fluctuations in a densely populated area. Several contributions have demonstrated the environmental sensitivity of the region during Quaternary time as documented by the record of Pleistocene and Holocene glacial advances in the Andean headwaters of the fluvial systems (e.g. Espizúa 2004, 2005; Espizúa & Pitte 2009; Messager 2010) along with geomorphological, palaeoenvironmental and palaeoclimatic studies (Baker et al. 2009; Paez et al. 2010). In order to understand the nature and characteristics of the present landscape, analysis of the Late Pleistocene and Holocene period is especially important. This key time interval covering the recent geological past includes a dramatic climatic change: the transition of the last glacial cycle to the present interglacial (Saltzman 2002). In addition, the Cordillera Frontal piedmont is considered as one of the source areas of the aeolian deposits of central Argentina (Zárate 2003; Mehl et al. 2012). Knowledge of the sedimentary record is therefore significant to validate the current models of aeolian sedimentation. These issues have renewed interest in the area and instigated multidisciplinary analysis by our research team. The studies, still under progress, include stratigraphical, sedimentological, geochronogical, morphostructural and palaeontological analysis, with the general aim of reconstructing the environmental and climatic conditions during Late Quaternary time across the Cordillera Frontal piedmont (e.g. Mehl & Zárate 2012; Rojo et al. 2012) and the eastern piedmont of San Rafael block, situated to the south (Tripaldi et al. 2011). Simultaneously, other authors (e.g. Pepin 2010; Pepin et al. 2013; Casa et al. 2011) have focused on tectonic, geomorphological and geochronological analyses in the study area (e.g. Cordón del Carrizalito piedmont, Las Tunas fluvial system). The purpose of this paper is to provide a general overview of the Quaternary stratigraphy and evolution of the Cordillera Frontal piedmont at Valle de Uco. Special emphasis is placed on Late Pleistocene and Holocene alluvial sequences that exhibit a suitable stratigraphic resolution for palaeoenvironmental reconstructions. The chronology and morphotectonic of the area are also analysed, along with the composition and provenance of the sediments. The final aim is to contribute to the understanding of the landscape dynamics in an active tectonic setting within the context of the Quaternary climate cycles. Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Perucca, Laura Patricia A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Geología "Dr. Emiliano Aparicio". Gabinete de Neotectónica y Geomorfología; Argentina

Los mamíferos fósiles del este de la Región Pampeana de Argentina constituyeron la base del esquema cronológico y biostratigráfico continental del Cenozoico tardío de América del Sur. Se presenta una nueva asociación faunística para el sector occidental de la región, proveniente de Santa Rosa (provincia de La Pampa), se evalúa su contexto sedimentario y se propone un esquema paleoambiental para el área. Esta asociación de mamíferos pleistocenos es la más numerosa y diversa registrada en una misma localidad en la provincia. Está integrada por los siguientes taxones: Glyptodon clavipes Owen, Doedicurus sp. (Xenarthra, Cingulata), Megatherium americanum Cuvier, Glossotherium robustum (Owen), Scelidotherium sp. (Xenarthra, Folivora), Toxodon sp., (Notoungulata, Toxodontidae), Lama sp. (Artiodactyla, Camelidae), Equus (Amerhippus) sp. e Hippidion sp. (Perissodactyla, Equidae). Los niveles portadores corresponden a un ambiente canalizado de tipo fluvial que habría funcionado como una zona de escurrimiento que drenaba el exceso de agua pluvial hacia una depresión topográ- fica (Laguna Don Tomás). Sobre la base de la posición estratigráfica relativa en la secuencia y la correlación con otras localidades de la región, se infiere que los niveles portadores se habrían acumulado durante el Pleistoceno tardío. En el Sitio 1 se registran Glyptodon clavipes, Megatherium americanum y Glossotherium robustum, taxones característicos de los Pisos-Edades Bonaerense y Lujanense, y Equus (Amerhippus), taxón exclusivo del Lujanense, por lo que esta nueva asociación es asignable al Piso-Edad Lujanense (Pleistoceno tardío−Holoceno temprano). Su presencia en estos depósitos corrobora la asignación temporal propuesta a partir de los sedimentos portadores. Fossil mammals from the Eastern sector of the Pampean Region (Argentina) provided the basis for the chronological and bios- tratigraphical continental scheme of the South American late Cenozoic. A new faunal assemblage from the Western area of the region (Santa Rosa, La Pampa Province) is presented along with the analysis of its sedimentary and stratigraphic context, and a paleoenvironmental re- construction. The mammalian faunal assemblage is the largest and more diverse reported from a single locality in La Pampa province and is composed by Glyptodon clavipes Owen, Doedicurus sp. (Xenarthra, Cingulata), Megatherium americanum Cuvier, Glossotherium robustum (Owen), Scelidotherium sp. (Xenarthra, Folivora), Toxodon sp., (Notoungulata, Toxodontidae), Lama sp. (Artiodactyla, Camelidae), Equus (Amerhippus) sp. and Hippidion sp. (Perissodactyla, Equidae). The fossil bearing levels represent a fluvial−like channel environment that drained the rain water excess towards a nearby topographic depression (Laguna Don Tomás). According to the relative stratigraphic position in the sequence and the correlation with other localities of the region, the fossil bearing levels would have accumulated during the Late Pleis- tocene. Among taxa recovered at Sitio 1, Glyptodon clavipes, Megatherium americanum and Glossotherium robustum are characteristic species of the Bonaerian and Lujanian Stages-Ages, while Equus (Amerhippus) is an exclusive taxon of the Lujanian. Consequently, this new faunal assemblage is assignable to the Lujanian Stage-Age (Late Pleistocene−Early Holocene). Its presence in the analyzed deposits confirms the chronology proposed from the bearing levels. Fil: Montalvo, Claudia Inés. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Bargo, María Susana. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

We report here the results of detailed 210Pb analysis from two lake sediment cores collected from Lagunas Encadenadas del Oeste (LEO), located in the southern Argentinean Pampas (37°S, 62°W). Non-exponential and non-monotonic 210Pbuns depth-profiles in the sedimentary record of these shallow lacustrine systems indicate the interaction of complex processes behind radionuclide fluxes and lake sedimentation. The chronologies and sediment accumulation rates (SAR) for the lake sediment sequences were modeled using different 210Pb-based mathematical models. Since modeled 210Pb ages must be validated against independent stratigraphic markers of known age, two chrono-stratigraphic markers were selected to control the upper and lowermost parts of the 210Pb dated sediments. The younger stratigraphic marker of AD 1980 ± 2 corresponds to an uppermost organic carbon-rich mud accumulated by 1977–78 matching the most noticeable lake highstand occurred during the 20th century, registered on instrumental and paleolimnological records across the Pampean Plains. The oldest stratigraphic marker corresponds to AD 1878 ± 10 matching with a high lake productivity and wet phase related to anomalously intense rainfall and flooding events in southeastern South America for AD 1877–1878. When comparing the resulting ages to the stratigraphic markers, our results show that CRS-model (constant rate of supply) performs better than the other models. Thus, these independent chronostratigraphic markers used along the sedimentary records were critical to validate 210Pb-derived ages and therefore to select the most appropriate model to establish the chronological framework of the recent sediments of the LEO system. The CRS-model appears to be an adequate technique for deriving ages and SAR in the LEO sedimentary record and other Pampean lacustrine systems under strong hydrological variability. Fil: Cordoba, Francisco Elizalde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina Fil: Piovano, Eduardo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Guerra, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Mulsow, Sandor. Universidad Austral de Chile; Chile Fil: Sylvestre, Florence. Centre National de la Recherche Scientifique; Francia Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

The Andean cordillera, and its piedmont in the central western Argentina, has been long considered as one of the main source areas of detritus for the Chaco-Pampean plain sand dune fields and loess/loess-like deposits of central Argentina. The main goal of this study is to evaluate the composition of the late Pleistocene-Holocene alluvial deposits of the Andes cordillera piedmont, from 33° to 34° S. The results are interpreted in the context of the regional geology, tectonic setting of the study area and its implications in the continent-wide perspective of modern alluvial sands proposed by Potter (1994). Sampling was conducted at the alluvial stratigraphic sequences of four study sites along three Andean piedmont arroyos; modal mineralogy in the very fine sand fraction (3 phi to 4 phi) was determined using standard petrographic microscope methods. Q:F:LF average compositions indicate that the Late Pleistocene-Holocene very fine-grained alluvial sands of the Cordillera Frontal piedmont reflects the modern lithic arenites of the Argentine Association reported by Potter (1994). The results show two geologically distinct sources in the catchment areas, volcaniclastic and metamorphic rocks. High concentrations of mica and volcanic glass are likely related to particle morphologies and to the deposition sedimentary environment recorded in the alluvial sequences-floodplains. The overabundance of micas over the volcanic glass in the mid-late Holocene alluvial sequence indicates the drainage of a metamorphic area at the expense of other lithological sources. Source areas are located mainly in the Frontal cordillera, and to a lesser extent, in the piedmont Tertiary deposits, another likely source for the analyzed Quaternary alluvial sediments. The mineralogical signature of the late Pleistocene and Holocene alluvial sequences is in agreement with the composition of the southern Pampean sand mantles, loess and loess-like deposits mainly formed by a volcanic mineral assemblage with source areas placed at the headwaters of the main Andean rivers. Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Blasi, Adriana. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

Desde el objetivo de desarrollar estrategias de conocimiento proyectual alternativas de caracter sociofisicas dentro de un urbanismo focalizado sobre el ambiente del hombre, a partir de la premisa que considera a la ciudad como una compleja articulacion de lugares (en sentido antropologico), se ha investigado una articulacion estrategica entre las siguientes dimensiones esenciales del lugar: las practicas sociales relacionadas a determinados grupos humanos; las significaciones de esas practicas para los grupos que las desarrollan y para el resto de los grupos de un determinado lugar; los rasgos configurativos del escenario que hacen de soporte a las practicas sociales y la significacion con que estos y las practicas sociales estuvieran cargados. La hipotesis fundamental establece que: segun sea la configuracion del esquema socio-fisicosimbolico de articulacion de estos elementos, o esquema genetico del lugar, surgiran las claves para comprender si en un determinado lugar urbano estan dadas o no, las condiciones esenciales para desarrollar procesos participativos de planificacion urbana ambiental. A partir de esta hipotesis el trabajo fundamenta una respuesta posible sustentada en la articulacion estrategica entre: congruencias sociofisicas, (hacen referencia al nivel de adecuacion de un determinado escenario para el despliegue sustentable de determinadas practicas sociales), y correspondencias sociosimbolicas (hacen referencia a la coherencia entre las significaciones proyectadas desde distintos grupos humanos a partir de sus actividades asociadas a un escenario particular). SUMMARY Since the objective of developing alternative strategies of projectual knowledge of sociophysical character inside of an urban development focused on the environment of man, on the premise that considers the city as a complex articulation of places (in anthropological sense), a joint strategic between following essential dimensions of place, comes under investigation social practices relating to certain groups of humans; the meanings of these practices for the groups that develop and the rest of the groups of a particular place; features that form the stage make support to social practices and the significance that these and social practices were loaded. The basic hypothesis states that: depending on configuration schema socio-physical - symbolic of articulation of these elements, or genetic scheme in place, will emerge the keys to understand whether or not, are given in a particular urban place the preconditions for developing participatory processes of urban environmental planning. Beginning in this work hypothesis underlying a possible response based on the strategic joint between: socio-physical congruence (refer to the adequacy of a specific stage for sustainable social practices deployment level) and socio-symbolic correlation (refer to the coherence between the meaning projected from different human groups of activities associated with a particular stage).

The main goal of this paper is to analyze the late Quaternary alluvial record of the Andean piedmont between 33° and 34°S (Mendoza, Argentina) reconstructing the prevailing paleoenvironmental conditions and discussing their regional significance. The analysis was carried out along the outcrops of Arroyo La Estacada and its tributary Arroyo Anchayuyo, complementary sections were described at Arroyo Grande and Arroyo Yaucha. The sedimentological, stratigraphical and geochronological (radiocarbon and OSL dating) results as well as the paleoenvironmental interpretation are presented and discussed on the basis of the geomorphological units identified at the piedmont fluvial systems. Late Quaternary deposits of Arroyo La Estacada compose three main geomorphological units consisting of an extensive aggradational plain, a fill terrace and the present floodplain -which is not analyzed in this contribution- At the aggradational plain a distal alluvial fan lithofacial association was determined, mainly related to overbank sheet fluid overflows and probably temporary inactive channels of sandy-like braided streams between ∼50 ka BP and the early Holocene. The mid-late Holocene fining upward alluvial sequence of the fill terrace corresponds to a sinuous fluvial system lithofacial association. The mid-to late Holocene alluvial sequence exposed at Arroyo Grande banks shows a fining upward sequence probably related to a sinuous fluvial system lithofacial association. Finally, in the Arroyo Yaucha the upper and lower terraces analyzed in this study record a Late Glacial and Holocene fining upward alluvial sequence of a sinuous fluvial system lithofacial association. The late Pleistocene - early Holocene dynamic of the Andean piedmont documents an interval of alluvial aggradation characterized by the occurrence of sandy systems similar to braided rivers in the distal fan environments. The mid-late Holocene is marked by aggradation in sinuous fluvial systems and by two major episodes of degradation registered across the fluvial systems of the study area. This paleoenvironmental reconstruction allowed us to propose an evolutionary scheme and chronology of the major fluvial landscape landforms contributing to the general understanding of the sedimentological and geomorphological dynamic during the late Quaternary. Fil: Mehl, Adriana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

The Andean piedmont of Mendoza is a semiarid region covered by extensive and partially vegetated dune fields consisting of mostly inactive aeolian landforms of diverse size and morphology. This paper is focused on the San Rafael plain (SRP) environment, situated in the distal Andean piedmont of Mendoza (34° 30′S), and reports the sedimentology and OSL chronology of two representative exposures of late Quaternary deposits, including their paleoenvironmental and paleoclimatic significance. Eleven facies, including channel, floodplain, fluvio–aeolian interaction, and reworked pyroclastic and aeolian deposits, were described and grouped into two facies associations (FA1 and FA2). FA1 was formed by unconfined sheet flows, minor channelized streams and fluvial–aeolian interaction processes. FA2 was interpreted as aeolian dune and sand-sheet deposits. OSL chronology from the SRP sedimentary record indicates that between ca. 58–39 ka and ca. 36–24 ka (MIS 3), aggradation was governed by ephemeral fluvial processes (FA1) under generally semiarid conditions. During MIS 2, the last glacial maximum (ca. 24–12 ka), a major climatic shift to more arid conditions is documented by significant aeolian activity (FA2) that became the dominant sedimentation process north of the Diamante–Atuel fluvial system. The inferred paleoenvironmental conditions from the SRP sections are in broad agreement with regional evidence.

Interactions between human societies and the environment that they inhabit have been a controversial topic in archaeology for at least the past fifty years. Currently, modern theoretical approaches take this subject as a key issue in their research agenda. This paper presents a review of the main outcomes of several archaeological and multidisciplinary South American projects related to this theme. The case-studies discussed here are all located within arid settings, and can be grouped into three broad geographic areas: Puna (or Altiplano) of northwestern Argentina, Cuyo (west-central Argentina), and southern Patagonia. These regions cover a wide latitudinal range extending from 22° to 52° S. They were selected for comparison due to environmental similarities, and a common record of past climate impacts mainly related to the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA). Although the impacts of these climatic changes were locally heterogeneous in their intensity and the quality of the available information is regionally variable, they provide a base-line for comparison and supra-regional integration. The integration of archaeological and palaeoenvironmental data on this broad supra-regional spatial scale allows us to identify interesting historical trajectories associated with particular time periods. As an example, there are some spatial rearrangements of large populations during the MCA, in the three areas. Additionally, there are variable patterns in the changes associated with the different social contexts that impose specific demographic and economic constraints. Finally, this study sets the basis for new questions and provides a guide to the methodological and theoretical issues that we need to address in order to answer them.

Marine Isotope Stage 3 (MIS 3) is characterized by high climatic variability resulting from numerous centennial to millennial scale events. The environmental and climatic reconstruction of this interval is restricted by the sparsity of high-resolution (centennial-scale) terrestrial records in most of South America. This contribution is an attempt to reconstruct the general environmental and climatic conditions of southern South America during MIS 3 by means of continental records located in central Argentina; this is an extensive and heterogeneous region made up of diverse geomorphological settings under different climatic conditions. Therefore, the main features of several aeolian and fluvial records situated in different geomorphological settings across the region are overviewed. The results indicate the predominance of regional aggradation during MIS 3 with differences in the accumulation rates and dominance of either aeolian or fluvial deposits depending on the geomorphological setting. The aggradation process was interrupted by stability intervals evidenced by paleosols in the San Rafael plain, the San Luis paleo-dunefield, the eastern Sierras Pampeanas piedmont and the eastern Pampean plain. The paleosols might represent lapses of decreasing aeolian input and perhaps more humid conditions. In addition, paleobiological indicators from alluvial sequences suggest higher temperatures and water availability between 35 and 31 ka in the Andean piedmont, while dry subhumid or strongly seasonal conditions with alternating subhumid-humid phases were inferred in the eastern Pampean plain during MIS 3. These intervals tend to cluster during the second part of MIS 3, and might reflect the environmental responses to some of the climatic oscillations that occurred during MIS 3. Detailed analysis and a more adjusted chronology are needed to correlate the aeolian and fluvial episodes along with the stability intervals at regional and continental scales.

This paper is focused on the paleoecological analysis of a mollusc succession cropping out on the right margin of La Estacada stream in the Andean piedmont of Mendoza, Argentina (33°28′ S, 69°03′ W). The stratigraphic section, mainly composed of fine sands, interbedded with levels of silty clays and organic matter, records the interval between 35.2–35.5 14C ka B. P. and 31.5–31.6 14C ka B.P. The mollusc succession is represented by freshwater and land snails: Biomphalaria peregrina (Planorbidae), Lymnaea viator (Lymnaeidae), Succinea meridionalis (Succineidae), Rotadiscus amancaezensis (Charopidae) and Radiodiscus sp. aff. Radiodiscus quillajicola (Charopidae). The dominance of semi-aquatic and hygrophilous land snails, suggests the development of a vegetated shallow water body, probably a damp habitat occasionally submerged, with four main stages of evolution related to fluctuating water levels. The abundance of shells together with the stable isotope composition of carbonate shells of L. viator (δ13C and δ18O) and the presence of Radiodiscus sp. aff. Radiodiscus quillajicola and R. amancaezensis suggest relatively warm and wet conditions. Based on its radiocarbon chronology and the paleoecological reconstruction, the studied section is recording a mild interval corresponding to an interstadial (Marine isotope stage 3) of the last glacial cycle.

The late Miocene Chasicoan mammal-bearing deposits exposed along the lower reach of Arroyo Chasico are composed of cross-bedded, very fine sandstones interpreted as a channel-bar deposit (lithofacies association 1) grading upward into sandy siltstones (lithofacies association 2), probably accumulated through relatively high-density flows in a marginal channel and/or floodplain environment. The uppermost levels are dominantly composed of mudstones and sandy siltstones (lithofacies association 3) deposited in generally low-energy conditions of sedimentation in a swampy environment. Several paleosols (lithofacies P) are present, indicating that the succession was the result of episodic fluvial sedimentation. The volcaniclastic composition (primary and reworked pyroclastics) suggests that the fluvial system drained the westward region by the Andean foothills. An impact event dated at 9.23 ± 0.09 Ma and recorded by impact glasses (escorias) during deposition of lithofacies Sp enables the fine tuning of the chronology of the deposits through high-resolution magnetostratigraphic profiles, which indicate that the approximately 9.4 m thick succession recorded by lithofacies association 1 and 2 accumulated between 9.43 and 9.07 Ma. The lithofacial arrangement of the succession does not support the current differentiation of the Arroyo Chasico Formation into the Vivero and Las Barrancas members. Previous biostratigraphic interpretations contain significant inconsistencies in light of the revised stratigraphy proposed here.

The Pampas plain (30°–41°S) has historically been considered as a sector that evolved independently from the adjacent Andean ranges. Nevertheless, the study of the Pampas showed that it is reasonable to expect an important influence from the Andes into the extraandean area. The Pampas plain can be divided into two sectors: the northern portion, adjacent to the Pampean Ranges, has been studied by Davila (2005, 2007, 2010). The southern sector (34°–41°S) is the objective of the present work. The study of this area allowed to characterize two separate foreland basins: the Southern Pampa basin and the Northern Patagonian basin. The infill is composed of Late Miocene and Pliocene units, interpreted as distal synorogenic sequences associated with the late Cenozoic Andean uplift at this latitudinal range. These foreland basins have been defined based on facies changes, distinct depositional styles, along with the analysis of sedimentary and isopach maps. The basins geometries are proposed following De Celles and Gilles (1996) taking into account the infill geometry, distribution and grain size. In both cases, these depocenters are located remarkably far away from the Andean tectonics loads. Therefore they cannot be explained with short-wave subsidence patterns. Elastic models explain the tectonic subsidence in the proximal depocenters but fail to replicate the complete distal basins. These characteristics show that dynamic subsidence is controlling the subsidence in the Southern Pampas and Northern Patagonian basins. Fil: Folguera, Alicia. Secretaria de Industria y Mineria. Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales; Argentina Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Tedesco, Ana María. Secretaria de Industria y Mineria. Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales; Argentina Fil: Davila, Federico Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos; Argentina

The field properties, micromorphology, grain-size, geochemistry, and optically stimulated luminescence (OSL) ages of two late Quaternary sections have been used to reconstruct the sequence of pedosedimentary processes and to provide insights into landscape evolution in part of the Northern Pampa of Argentina. Paleosols developed in paludal sediments adjacent to the Paraná river at Baradero and in loess at Lozada can both be correlated and linked to other sites, thus enabling for the first time the tentative recognition and tracing of a diachronous soil stratigraphic unit that probably spans the equivalent of at least part of marine oxygen isotope stage (OIS) 5. The paleosol at Lozada was truncated and buried beneath fluvial sediments during the time span of OIS 4 and 3. Eolian gradually replaced paludal inputs at Baradero over this period, and there were also two clearly defined breaks in sedimentation and development of paleosols. The period corresponding to OIS 2 was marked by significant loess accumulation at both sites with accretion continuing into the mid-Holocene only at Lozada. The more developed nature of the surface soil at Baradero probably reflects a combination of a moister climate and a longer soil-forming interval. Fil: Kemp, Rob A.. University of London; Reino Unido Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Toms, Phillip. University of Gloucestershire; Reino Unido Fil: King, Matthew. University of London; Reino Unido Fil: Sanabria, Jorge Alberto. Universidad Nacional de Córdoba; Argentina Fil: Arguello, Graciella. Universidad Nacional de Córdoba; Argentina

A bed with several serpulid build-ups is described from a Holocene outcrop at Quequen Grande River, Argentina. The tubes were dated at 6360 ± 80 years BP. The morphology and size parameters of the serpulids were compared to different species of serpulids from the literature and tubes of Ficopomatus enigmaticus , Hydroides dianthus and Hydroides plateni from Argentinean waters. In spite of the fact that today only F. enigmaticus constructs build-ups in Argentine brackish environments, the fossil tubes could not be assigned to this species, but instead, they show close similarities to those of the two species of Hydroides . The sequence is interpreted as having originated from a brackish environment. At present, neither the endemic H. plateni nor any other species of Hydroides construct build-ups in brackish waters of southern South America. This suggests, that suitable environments to construct aggregates were more widespread than today or that the invasion of F. enigmaticus replaced Hydroides ; alternatively various causes may have acted jointly.

Traditionally, the long-term landscape evolution of the southern Buenos Aires ranges of east central Argentina has been related to the influence of the Andean orogeny. We describe the large-scale morphological units and associated weathering products in the Tandilia and Ventania ranges. Two main planation surfaces are encountered at varying altitudes in different sectors of these ranges. The lower surface is characterized by roots of kaolinized weathering profiles in the Tandil area and silicified conglomerates around Sierra de La Ventana. In an interpretative model linking the range morphogenesis to the tectonosedimentary evolution of the bordering Salado and Colorado Basins, we suggest that the main morphogenetic stages are related to the late Jurassic-early Cretaceous south Atlantic rifting and Miocene tectonic reactivation induced by the Andean orogeny. Thus, the uplifted surfaces appear much older than commonly believed: pre-Cretaceous and Paleogene. Although they contradict recent results of apatite fission-track studies along the South America and South Africa passive margins, the implied low denudation rates (∼4 m/My) can be explained by the limited Meso-Cenozoic uplift suffered by the southern Buenos Aires ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.

The environmental heterogeneity of southern Mendoza led to different environmental responses during the mid-Holocene. More arid conditions and perhaps higher temperatures were dominant in the lowlands, while the high Andes experienced increased snowfalls and neoglacial readvances from ca 6000 to 4000 years BP. The opposing climate pattern of the region in comparison with the western Pacific foothills of the Andes is apparently related to the different influences exerted by the Westerlies on both sides of the Cordillera. The archeological record of this time period is represented by very few sites with a low density of material. Both the temporal distribution of the radiocarbon dates and the occupation index suggest a significant decrease of human occupations manifested by a chronological hiatus which varies in timing and duration according to the areal scale of analysis. The coincidence of the occupational hiatus and the low amount of archeological evidences would point to abandonment and/or a change related to a low intensity pattern of land use across the region. These human responses seem to parallel the general arid climatic conditions of the mid-Holocene although more detailed information and particularly numerical dates are needed to test the hypothesis. Site formation processes, including site disturbance produced by later human occupations are alternative explanations also evaluated to give account of the archeological record.

Known since Darwin's time, the Plio-Pleistocene succession exposed at the Chapadmalal sea cliffs have provided abundant mammal remains even though palaeobiological studies are scarce. Different authors have identified several assemblages in this stratigraphic interval of homogeneous lithology, which records an important mid-Pliocene faunal turnover dated at ca. 3.3 Ma. This paper examines the palaeoecological characteristics and the regional importance of this faunal turnover: 37% of all genera and 53% of all species became extinct between the older Chapadmalalan and the younger Barrancalobian chronostratigraphic units, a level that is actually higher than the percentage of genera extinct at the global-scaled Cretaceous - Tertiary extinction. The palaeoecological analysis permits to infer that the species-rich Chapadmalalan fauna seems to have been very balanced from the trophic - energetic point of view. On the other hand, the succeeding and less-explored Barrancalobian represents a relatively poorer environment, highly unbalanced in terms of the herbivore - carnivore relationships, due mainly to the absence of medium to large mammal and bird carnivores. The cause of the mid-Pliocene faunal turnover is still debatable. Climatic change has been traditionally related to this faunal turnover. Stratigraphically, an impact event dated at ca. 3.3 Ma is recorded in the succession. This event coincides with a change in the deep-sea stable isotopic record, reflecting a sudden change in climate and ocean circulation. This suggests that the impact might have induced regional faunal extinctions. Correlation with other areas different from the coast of Buenos Aires Province is needed to establish the geographic scale of the extinction. New fossils will provide a more complete and accurate picture of this remarkable faunal turnover. Fil: Vizcaíno, Sergio Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentina Fil: Fariña, Richard A.. Universidad de la República; Uruguay Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Bargo, María Susana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentina Fil: Schultz, Peter. University Brown; Estados Unidos

Loess-like deposits cover much of central Argentina and preserve a rich record of impacts since the late Miocene. The present contribution focuses on two localities containing Quaternary impact glasses: along the coastal sequences near Centinela del Mar (CdM) and from near Rio Cuarto (RC). These highly vesicular glasses contain clear evidence for an impact origin including temperatures sufficient to melt most mineral constituents (1700°C) and to leave unique quench products such as β-cristobolite. The CdM glasses occur within a relatively narrow horizon just below a marine transgression expressed by a series of coastal paleo-dunes and systematic changes in the underlying sediments. High-resolution 40Ar/39Ar dating methods yielded an age of 445±21 ka (2σ). Glasses were also recovered from scattered occurrences lower in the section but were dated to 230±40 ka. This inconsistency between stratigraphic and radiometric age is most likely related to a nearby outcrop of glass that had been exposed and locally re-deposited in coastal lagoons during the last marine transgression at 125 ka. Sediments containing the original impact glass layer are now missing due to an unconformity, perhaps related to subsequent marine transgressions after the impact (410 ka and 340 ka) and hiatuses in deposition. Two different types of impact glasses from RC yield two distinct dates. High-resolution 40Ar/39Ar dating of fresher-appearing glasses (well-preserved tachylitic sheen) indicates an age of 6±2 ka (2σ). Independent fission track analyses yielded a similar age of 2.3±1.6 ka (2σ). More weathered glasses, however, gave significantly older ages of 114±26 ka (2σ). Consequently, materials from two separate Quaternary impacts have been recovered at Rio Cuarto. The younger glasses are consistent with previously reported carbon dates for materials on the floor of one of the large elongate structures. The depths of excavation for the RC and CdM impacts are very different. While the RC glasses are largely derived from near-surface materials, the CdM glasses from the upper level contain added components consistent with Miocene marine evaporites at a depth of about 400–500 m (e.g., high CaO and P2O5). The CdM glasses also incorporated older loess-like sediments from depth based on the geochemistry. Several ratios of key trace and rare earth elements of sediments of different ages from the Miocene to the Holocene indicate a systematic compositional change through time. Such changes calibrate the observed differences in glass composition from their host sediments and further indicate incorporation of materials from depth. Consequently, the Argentine loess-like sediments preserve evidence for at least four separate Quaternary impacts. Based on foreign components in the glasses, the CdM impact very likely produced a crater (now buried or eroded) once as large as 6 km in diameter. The younger RC glasses, however, are consistent with shallower excavation consistent with an oblique impact.

We present rare-earth element (REE) and Sr-Nd isotopic data for Argentinian loess (28-38°S) with two aims: (1) to examine the source regions of Argentinian loess and the constraints that these put on palaeo-wind directions; (2) to further investigate the source of Antarctic ice-core dust and to test the hypothesis that some of it could be derived from a region to the north of Patagonia - into which the dry, dusty, westerly dominated Patagonian climate expanded during Quaternary glacial maxima. Sr-Nd isotopic data for Argentinian loess from north of 37°S are distinct from Patagonian loess compositions in that they have more radiogenic Sr (87Sr/86Sr=0.7059-0.7123) and less radiogenic Nd (ε Nd =-0.8 to -6.4). REE patterns and Sr-Nd isotopic values are relatively homogeneous for multiple samples taken from single loess sections but show significant differences between sections. In general, there is a northward change from Patagonia-like REE patterns and isotopic values away from volcanogenic signatures and towards those that are more like the continental crust. The latitudinal Nd isotopic pattern is remarkably similar to that for Andean volcanic rocks and suggests derivation of loess from the Andes by more-or-less direct westerly transport. For loess sections in the north, the data imply a contribution from Palaeozoic gneisses to the northwest in the Chilean Altiplano. Sr-Nd data for extra-Patagonian Argentinian loess north of 37°S do not support a significant role for this source region in supplying dust to Antarctica at the last glacial maximum. This conclusion contrasts with previous studies that suggest a significant northward shift in the climatic belts - and in particular the westerlies and the Antarctic Polar Front - during Quaternary glacial maxima. Very systematic relations between the Sr-Nd isotopic composition of loess and their Andean source highlights shifts in the Sr isotopic composition of loess to more radiogenic values and strongly suggests that the slight offset between Patagonian loess and ice-core dust identified by previous workers is due to grain-size differentiation effects. Fil: Smith, James. University of London; Reino Unido Fil: Vance, Derek. University of London; Reino Unido Fil: Kemp, Rob A.. University of London; Reino Unido Fil: Archer, Corey. University of London; Reino Unido Fil: Toms, Phillip. University of London; Reino Unido Fil: King, Matthew. University of London; Reino Unido Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina

The Piedra Museo site (Santa Cruz, Argentina), excavated over the past nine years has yielded a rich archaeological record, which contributes to the discussion on the first peopling of the Americas. We present here a new study of the site, based on an analysis of the stratigraphy, spatial distribution or archaeological remains, bone taphonomy, and discussion of new AMS-14C dates. We conclude that remains of extinct species with cut-marks from the lower levels are contemporaneous of stone tools and cores from the same levels. This demonstrates that humans were present in the southern part of Patagonia around 10 300 and 11 100 years BP and suggests that hunting of large mammals was a part of their subsistence strategies. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS. Le site de Piedra Museo, Santa Cruz, Argentine, fouillé au cours des neuf dernières années, a livré de nombreux restes archéologiques et a fait l'objet de plusieurs datations 14C. La présente étude a pour objectif d'analyser le mode de formation du remplissage, la distribution spatiale des vestiges et les modifications anthropiques sur les restes osseux provenant des couches inférieures. Les implications de deux nouvelles datations 14C–AMS pour ces couches sont également discutées. Nous concluons que les couches inférieures de ce site conservent les traces d'une fréquentation humaine pléistocène, datée entre 10 300 et 11 100 BP. Fil: Ramirez Rozzi, Fernando V.. Centre National de la Recherche Scientifique; Francia Fil: D'Errico, Francesco. Centre National de la Recherche Scientifique; Francia. Institut de préhistoire et de géologie du Quaternaire; Francia Fil: Zárate, Marcelo Arístides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Cientifícas y Tecnológicas; Argentina

A representative section of the Holocene alluvial record of the southern Pampas (Argentina) com prises a sequence of clastic sediments, a diatomite and two palaeosols. Detailed macro- and micromorphological descriptions provide the basis for the reconstruction of its pedosedimentary history. Combining the pedosedi mentary reconstruction with palaeoecological data allows a detailed overview of alluvial landscape development and associated palaeoenvironmental change in the region during the Holocene. The early-Holocene shift from a subhumid dry to humid climate was marked initially by a diminution in clastic sedimentation, the development of the Puesto Callejón Viejo Soil and then re-establishment of fluvial aggradation with a dominance of bioclastic sedimentation. Loess inputs increased during the mid-Holocene as the climate reverted to subhumid dry, and temporary subaerial exposure of the sediments led to the formation of the Puesto Berrondo Soil. More variable environmental conditions followed with natural fluvial aggradation ceasing in the late Holocene, though aeolian sedimentation has continued until the present day. The resultant surface accretionary soil has been modified by recent alluvial inputs from flood events linked to agricultural disturbance in adjacent catchments.

In the Central Andes of Argentina, evidences of early human occupations come from the Precordillera, a low mountain system which was under periglacial conditions prior to 14,000 14C yr BP, when the Cordillera Principal and Cordillera Frontal were glaciated. The corridors for human migration across the Andes may have opened before 13,000 14C yr BP. The Pleistocene/Holocene transition gave rise to a substantial variability of environments and consequently of natural resources for early people, who found in the Precordillera new ecosystems with suitable conditions for living. The first human groups arrived ca. 11,000 14C yr BP at Agua de la Cueva rockshelter, located at 2900 m above sea level in the western flank of the Precordillera. The occurrence of raw material outcrops close to the site and the archaeofaunistic record indicate a local and likely seasonal exploitation of mountain resources. These early people lived in a shrub steppe environment under cooler and probably wetter conditions in which camelids were the most important food resource. Since 9000 14C yr BP, warmer and drier conditions were dominant. Except for a lower intensity of human occupations, the site function of Agua de la Cueva seems to have remained the same.

The archaeology of the Pleistocene–Holocene Transition in the Pampas and Fuego-Patagonia is analyzed in light of the results obtained at recently excavated archaeological sites. These sites offer detailed artifactual, faunistic, chronological, and paleoecological information. Results from paleoecological research performed off site are also presented. Changes in climate, vegetation, and faunal composition are recorded, but the archaeological assemblages do not exhibit any clear-cut correspondent changes.

The region of central western Argentina is situated in a complex geological and tectonic setting with transitional features between major environmental, tectonic, and geomorphological domains. Preserved remnants of planation surfaces, which form the summit of major geological units, occur as discontinuous and isolated exposures with a remarkable geographical distribution along 600 km (33°–39° S). The main goal of this chapter is to summarize the available information and describe the main features and geological context of the planation surfaces preserved in the areas of the San Rafael block, Payenia, the Chical-co plain, and the Chadileuvu block situated in the southern part of Mendoza and western La Pampa provinces, central western Argentina. The common feature of the areas under analysis is the occurrence of remnants of planation surfaces at different altitudes which cut across bedrock of different composition (igneous, metamorphic, and sedimentary units) and varied age ranging from the Middle Proterozoic (Grenvillian age) to Middle Triassic continental sedimentary rocks. The development may have begun in the Triassic, before the Gondwana breakup and more than one planation surface might be present. During the Late Miocene synorogenic deposits covered the planation surface at the San Rafael block, very likely Payenia, and the Chical-co plain; no conclusive evidence is available in the area of the Chadileuvu block. As a result of tectonic activity (circa 7–6 Ma?), the region was fractured, differentially uplifted, and started a general exhumation process that partially removed the Late Miocene sedimentary cover from the San Rafael block and the eastern margin of Chical-co plain.