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Background and Objectives Certain demographic and clinical characteristics, including the use of some disease-modifying therapies (DMTs), are associated with severe acute respiratory syndrome coronavirus 2 infection severity in people with multiple sclerosis (MS). Comprehensive exploration of these relationships in large international samples is needed.Methods Clinician-reported demographic/clinical data from 27 countries were aggregated into a data set of 5,648 patients with suspected/confirmed coronavirus disease 2019 (COVID-19). COVID-19 severity outcomes (hospitalization, admission to intensive care unit [ICU], requiring artificial ventilation, and death) were assessed using multilevel mixed-effects ordered probit and logistic regression, adjusted for age, sex, disability, and MS phenotype. DMTs were individually compared with glatiramer acetate, and anti-CD20 DMTs with pooled other DMTs and with natalizumab.Results Of 5,648 patients, 922 (16.6%) with suspected and 4,646 (83.4%) with confirmed COVID-19 were included. Male sex, older age, progressive MS, and higher disability were associated with more severe COVID-19. Compared with glatiramer acetate, ocrelizumab and rituximab were associated with higher probabilities of hospitalization (4% [95% CI 1–7] and 7% [95% CI 4–11]), ICU/artificial ventilation (2% [95% CI 0–4] and 4% [95% CI 2–6]), and death (1% [95% CI 0–2] and 2% [95% CI 1–4]) (predicted marginal effects). Untreated patients had 5% (95% CI 2–8), 3% (95% CI 1–5), and 1% (95% CI 0–3) higher probabilities of the 3 respective levels of COVID-19 severity than glatiramer acetate. Compared with pooled other DMTs and with natalizumab, the associations of ocrelizumab and rituximab with COVID-19 severity were also more pronounced. All associations persisted/enhanced on restriction to confirmed COVID-19.Discussion Analyzing the largest international real-world data set of people with MS with suspected/confirmed COVID-19 confirms that the use of anti-CD20 medication (both ocrelizumab and rituximab), as well as male sex, older age, progressive MS, and higher disability are associated with more severe course of COVID-19. BACKGROUND AND OBJECTIVES: Certain demographic and clinical characteristics, including the use of some disease-modifying therapies (DMTs), are associated with severe acute respiratory syndrome coronavirus 2 infection severity in people with multiple sclerosis (MS). Comprehensive exploration of these relationships in large international samples is needed. METHODS: Clinician-reported demographic/clinical data from 27 countries were aggregated into a data set of 5,648 patients with suspected/confirmed coronavirus disease 2019 (COVID-19). COVID-19 severity outcomes (hospitalization, admission to intensive care unit [ICU], requiring artificial ventilation, and death) were assessed using multilevel mixed-effects ordered probit and logistic regression, adjusted for age, sex, disability, and MS phenotype. DMTs were individually compared with glatiramer acetate, and anti-CD20 DMTs with pooled other DMTs and with natalizumab. RESULTS: Of 5,648 patients, 922 (16.6%) with suspected and 4,646 (83.4%) with confirmed COVID-19 were included. Male sex, older age, progressive MS, and higher disability were associated with more severe COVID-19. Compared with glatiramer acetate, ocrelizumab and rituximab were associated with higher probabilities of hospitalization (4% [95% CI 1-7] and 7% [95% CI 4-11]), ICU/artificial ventilation (2% [95% CI 0-4] and 4% [95% CI 2-6]), and death (1% [95% CI 0-2] and 2% [95% CI 1-4]) (predicted marginal effects). Untreated patients had 5% (95% CI 2-8), 3% (95% CI 1-5), and 1% (95% CI 0-3) higher probabilities of the 3 respective levels of COVID-19 severity than glatiramer acetate. Compared with pooled other DMTs and with natalizumab, the associations of ocrelizumab and rituximab with COVID-19 severity were also more pronounced. All associations persisted/enhanced on restriction to confirmed COVID-19. DISCUSSION: Analyzing the largest international real-world data set of people with MS with suspected/confirmed COVID-19 confirms that the use of anti-CD20 medication (both ocrelizumab and rituximab), as well as male sex, older age, progressive MS, and higher disability are associated with more severe course of COVID-19.

Sedimentary records of Plio-Pleistocene intermontane basins of the Eastern Cordillera and the adjacent Puna Plateau in the Central Andes of NW Argentina (hinterland basins) are important geological archives that provide spatiotemporal insights into regional tectonism, the uplift history of basin-bounding mountain ranges, and associated depositional and paleoenvironmental changes. Here, we reconstruct the Plio-Pleistocene evolution of the intermontane Humahuaca Basin based on the study of depositional systems, unconformities, accumulation rates, depositional patterns, U–Pb geochronology, magnetostratigraphy, and sediment provenance of the Uquía Formation – a ca. 4.8–1.5-My-old sedimentary basin record consisting of a 100–400 m thick fining-upward stack of conglomerates, sandstones, and siltstones with intercalated volcanic tuffs. The sedimentary facies of the Uquía Formation comprise debris flow, deep sandy gravel braided alluvial fan deposits, sheetflood dominated, floodplains, and shallow ephemeral lake deposits. Facies characteristics and δ18O and δ13C values from pedogenic and palustrine carbonates indicate freshwater lacustrine conditions at the base and evaporative conditions towards the top of the Uquía Formation (ca. 2.3 Ma). During the deposition of the Uquía Formation, the Humahuaca Basin was already bounded by uplifted mountain ranges: (a) the Sierra Alta to the west, which experienced early uplift during the middle Eocene and increased exhumation from about 15 to 10 Ma; and (b) the Aparzo and Tilcara ranges to the east, whose deformation and uplift began about 15–10 Ma and culminated in the structural and fluvial separation of the Humahuaca Basin from the foreland by ca. 4.8 Ma in the center and by about 4.2 Ma in the southern sector of the basin. This is supported by variable unroofing patterns, the paleoenvironmental evolution, deposition of sheetflood dominated alluvial fans, and lacustrine deposits., This study was financially supported by the AGENCIA (PICT-2017-1010), PUE-INECOA (22920170100027CO) and UNSa (CI-UNSa 2287). We thank Dr. Marcelo Reguero and Dr. Pablo Ortiz for the valuable suggestions that improved this research. We are grateful for constructive and positive suggestions from Reviewers Dr. Oscar Limarino and anonymous. We also thank LA.TE. ANDES S.A. laboratory for their support of geochronology and we thank Mr. Omar Dominguez from the Geology Department, (CEGA-UNSa), for assistance during thin section preparation. EB thanks the Geomodels Research Institute of the University of Barcelona and the “Grup de Geodinàmica i Anàlisi de Conques” - 2017SGR596 (Generalitat de Catalunya).

Acute disseminated encephalomyelitis (ADEM) is an inflammatory emyelinating disease of the central nervous system that is usually considered a monophasic disease Post-vaccination ADEM has been associated with several vaccines, however, there is scarce information related to SARS-CoV-2 vaccines. We present the case of a 26- year-old female who suffered from ADEM four weeks after Gam-COVID-Vac administration.

Acute ischemic stroke (AIS) is a time-dependent emergency, since the greatest impact depends on the time elapsed to treatment. The objective of this work was to analyze door to needle (DTN) and start treatment (STT) times and the effect of pre-notification system (PNS) and the appropriate choice of the healthcare center on these variables. An observational study with data obtained from records of patients admitted to the Stroke Unit (SU) was conducted between August 2015 to December 2019. We analyzed the number of intravenous thrombolytic treatments (IVT), DTN and STT and compared them according to PNS use, direct arrival at the center with SU or arrival at another center for subsequent referral. An overall of 472 patients were hospitalized during the studied period and the treatment was performed in 143 out of 265 patients. One hundred thirty-seven patients arrived from another center, 70 received IVT. Average DNT with PNS and without PNS were 41 ± 23 and 81 ± 44 minutes, respectively (p = 0.001). STT on direct arrival to SU was 159 ± 59 minutes and to another center for referral was 199 ± 44 (p = 0.001). The use of a PNS and the direct choice of a center where IVT is performed significantly improve treatment.El accidente cerebrovascular (ACV) es una urgencia tiempo dependiente, ya que las conductas de mayor impacto pronóstico dependen del tiempo trascurrido. El objetivo de este trabajo fue analizar nuestros tiempos puerta aguja (TPA), comienzo aguja (TCA) y el efecto que tiene sobre estos el sistema preaviso y la elección adecuada del centro asistencial. Se realizó un estudio observacional con datos obtenidos de historias clínicas de pacientes internados en la unidad de ACV. Analizamos el número de tratamientos trombolíticos endovenosos, entre agosto 2015 y diciembre 2019. Comparamos TPA según utilización de pre-aviso, llegada directa por sus propios medios vs. en ambulancia sin pre-aviso, y TCA según llegada directa al centro con unidad de ACV vs. llegada a otro centro para posterior derivación. De 265 pacientes en ventana terapéutica, se realizó tratamiento en 143. Llegaron 137 pacientes derivados de otro centro, 70 recibieron tratamiento trombolítico. El TPA con sistema preaviso y sin preaviso fue 41 ± 23 (media ± DE) y 81 ± 43 minutos, respectivamente (p = 0.001). El TPA con llegada directa por sus propios medios 79 ± 43 y en ambulancia sin preaviso 84 ± 44 minutos (p = 0.7) a unidad de ACV. El TCA en llegada directa a unidad de ACV fue 159 ± 59 y a otro centro para su derivación 199 ± 44 minutos (p = 0.001). La utilización de un sistema de preaviso y la elección directa de un centro con unidad de ACV son medidas clave para reducir los tiempos de tratamiento.

Advances in cosmogenic nuclide exposure dating have made moraines valuable terrestrial recorders of palaeoclimate. A growing number of moraine chronologies reported from the Central Andes show that tropical glaciers responded sensitively to past changes in precipitation and temperature over timescales ranging from 103 to 105 years. However, the causes of past glaciation in the Central Andes remain uncertain. Explanations have invoked insolation-modulated variability in the strength of the South American Summer Monsoon, teleconnections with the North Atlantic Ocean, and/or cooling in the Southern Hemisphere. The driver for these past climate changes is difficult to identify, partly due to a lack of dated moraine records, especially in climatically sensitive areas of the southern Central Andes. Moreover, new constraints are needed on precisely where and when glaciers advanced. We use cosmogenic 10Be produced in situ to determine exposure ages for three generations of moraines at the Sierra de Aconquija, situated at 27°S on the eastern flank of the southern Central Andes. These moraines record glacier advances at approximately 22 ka and 40 ka, coincident with summer insolation maxima in the sub-tropics of the Southern Hemisphere, as well as at 12.5 ka and 13.5 ka during the Younger Dryas and the Antarctic Cold Reversal, respectively. We also identify minor glaciation during Bond Event 5, also known as the 8.2 ka event. These moraines register past climate changes with high fidelity, and currently constitute the southernmost dated record of glaciation on the eastern flank of the Central Andes. To contextualise these results, we compile 10Be data reported from 144 moraines in the eastern Central Andes that represent past glacier advances. We re-calculate exposure ages from these data using an updated reference production rate, and we re-interpret the moraine ages by taking the oldest clustered boulder age (after the exclusion of outliers attributed to nuclide inheritance) as closest to the timing of glacier advance—an approach for which we provide empirical justification. This compilation reveals that Central Andean glaciers have responded to changes in temperature and precipitation. We identify cross-latitude advances in phase with insolation cycles, the last global glacial maximum, and episodes of strengthened monsoonal moisture transport including the Younger Dryas and Heinrich Stadials 1 and 2. Our results from the Sierra de Aconquija allow us to constrain the southerly limit of enhanced precipitation associated with Heinrich Stadials at ∼25°S. More broadly, our findings demonstrate at both local and regional scales that moraines record past climate variability with a fine spatial and temporal resolution.

Alluvial river long profiles continually adjust to their water discharge (Qw) and sediment supply (Qs). Qw and Qs are in turn functions of local climatic and tectonic conditions. Hence, changes in the prevailing tectonic or climatic conditions will trigger adjustments to channel long profiles, either by channel incision into previously deposited sediments or by sediment deposition. Because fluvial terraces are abandoned floodplains that preserve ancient river elevation profiles formed from past Qs and Qw, they store information on past climatic or tectonic conditions. In NW Argentina, reconstructions of Pleistocene climate are sparse due to the limited availability of paleo-climatic records, such as stable isotope data from speleothems or lake cores. However, many intermontane basins within the Southern Central Andes of NW Argentina are characterized by multiple generations of fluvial-fill terraces, some of which date back several tens to hundreds of thousands of years. Here, we show that these geomorphic units provide an opportunity to extract information about paleo-climatic conditions. A combination of several geochronological techniques has revealed the history of a >200-m-thick fluvial-fill terrace sequence within the Quebrada del Toro. The terrace sequence experienced alternating episodes of incision and aggradation since at least 500 ka. Subsequent terrace surfaces appear to have formed following a cyclicity of ca. 100 kyr. From detrital sediment within those fill terraces, past Qs could be reconstructed for times of sediment aggradation based on cosmogenic 10Be concentrations. The analyses revealed that over the last ~500 kyr Qs has varied at most by a factor of 4, but overall has been relatively constant. As the slope of a river channel (and likewise, the slope of a well preserved terrace surface) is a function of incoming Qs and Qw, combining data of terrace slope and past Qs allowed us to reconstruct past Qw for the times represented by the ages of the terrace surfaces, which mark the onset of river incision. The analyses revealed that during these times, Qw was 10 to 80% higher than today. The results are in line with the few existing quantitative estimates of past precipitation changes in the Central Andes, but have the advantage of extending further back in time. Moreover, the widespread occurrence of fluvial-fill terraces throughout the Central Andes offers the opportunity to reconstruct past Qw with high spatial resolution, offering a new perspective regarding the impact of past climate changes on the sediment-routing system through space and time.

With an average elevation of about 3.7 km the semi-arid to arid Central Andean Plateau (Altiplano-Puna) constitutes the world’s second largest orogenic plateau. The internally drained region is characterized by compressional basin-and-range topography. Many of the basins in the Argentine sector of the plateau (Puna) are presently evaporitic salt pans, but during the Pleistocene the basins have repeatedly experienced high lake-level phases during pluvial periods. Due to protracted sedimentary infilling and sustained internal drainage conditions the basins have thick sedimentary sequences that have partially coalesced. The basins are bordered by reverse-fault bounded ranges, reaching 5 to 6 km elevation, but the history and extent of tectonic deformation in this region is not very well known. Global Navigation Satellite System (GNSS) data have been used to estimate decadal-scale tectonic shortening rates but the spatiotemporal pattern of surface deformation is complex and includes the compounding effects of subduction zone megathrust earthquake transients.Here, we use a combination of field observations, cosmogenic nuclide dating of deformed alluvial-fan surfaces, Interferometric Synthetic Aperture Radar (InSAR), and GNSS data time series to quantify Quaternary to decadal-scale tectonic deformation. The arid mountain ranges provide ideal conditions to observe deformation from multiple sensors, including TerraSAR-X, Sentinel-1, ALOS2, and ENVISAT. Furthermore, we rely on 12 m TanDEM-X topographic data to characterize 103-106 yr surface deformation using cosmogenic nuclide exposure dating and digital elevation model analysis. The Puna has been previously characterized as a region with little tectonic activity including very low levels of seismicity despite evidence for strike-slip and extensional faulting accompanied by mafic volcanism. The eastern plateau margins in particular record this type of kinematic regime, while the adjacent foreland is characterized by a higher level of seismicity and ongoing contraction. Here, we present evidence of ongoing contraction during the past two decades compatible with tectono-geomorphic phenomena that support the notion of tectonic shortening in the central Puna Plateau. For example, tilted shorelines associated with former lake-highstands along the flanks of an anticline and Neogene-Pleistocene growth strata associated with this structure indicate that shortening in this region has been sustained since the Neogene. InSAR and GNSS time series analysis permit the identification and characterization of previously unrecognized tectonic activity in adjacent sectors of the intermontane basins, thus helping to improve our understanding of crustal dynamics in the Central Andes.

The Central Andes region is a young, noncollisional, active orogen, formed as a consequence of the subduction of the Nazca oceanic plate underneath the South American continental plate. It achieves its greatest expression between 15° and 28°S, where a 30° subduction angle appears. The Central Andes appears delimited by two flat slab regions, both dipping 5 E: the Peruvian segment to the north and the Pampean segment to the south. The building of the Andes occurred in consecutive stages during Cenozoic times. Crust fusion at 1200 °C generated magma that reached the surface, resulting in a great volcanic arc that currently mostly constitutes the boundaries between the Andean countries (Peru, Bolivia, Chile, and Argentina). The crust deformation prompted the uplifting of a tectonic cordillera (the Eastern Cordillera) and the Volcanic Cordillera (Central Volcanic Zone), generating a first-order basin, the Altiplano–Puna High Plateau. The Andes are growing vertically and pushing horizontally to the east, creating the folding of the Subandean Ranges. The isostatic compensation was balanced by the sinking of the great Chaco Plain or foreland. The Eastern Andes has become an orographic barrier to the wet Amazonic winds. The Altiplano–Puna Plateau has turned into an arid region where salars, salt lakes, springs, and hot springs have formed. Deserts, salars, lakes, and volcanoes are the product of several factors such as the geology, tectonics, and climate typical of the endogenous and exogenous dynamics of the Central Andes.

Heinrich Max Sparn (1889-1966) castellanizó su nombre alemán por el de Enrique Sparn, con el cual firmó su obra bibliográfica en la Argentina. Desde 1918 hasta 1954 se desempeñó en la Academia Nacional de Ciencias de Córdoba (ANCC) donde tuvo una extensa carrera como bibliotecario, secretario y miembro de pleno derecho de la Academia. Asimismo fue miembro del Instituto de Bibliografía Regional del Departamento de Filosofía de la Universidad de Buenos Aires y Jefe de la Comisión de Coordinación de todas las bibliotecas de la Universidad de Córdoba. No solo fue un gran bibliotecario sino que además se destacó como bibliógrafo científico, llevando a cabo minuciosas investigaciones sobre los temas importantes de la época los que le permitieron realizar contribuciones científicas con aportes estadísticos, sociológicos, culturales y educativos. Se destacó por haber compilado abundante literatura de los siglos XIX y XX, especialmente sobre geología, mineralogía, paleontología, ciencias naturales e historia de las ciencias. Sus publicaciones suman un centenar de trabajos especialmente en actas, boletines y misceláneas de la ANCC. Se lo propone en este trabajo como el padre de la bibliografía científica argentina., The German librarian Heinrich Max Sparn (1889-1966), as Enrique Sparn, made a very important contribution to Argentinean bibliography during his extensive work at Córdoba National Academy of Sciences (ANCC), from 1918 to 1954. Sparn had written around 100 papers that were published in bulletins, proceedings and special volumes of the ANCC related to geology, mineralogy, paleontology, natural sciences, and history of sciences. He made all kinds of compilations of scientific bibliography, especially of the19th and 20th centuries. Furthermore, Sparn carried out research related to bibliographic aspects as well as statistical, sociological, cultural and academic analysis. Sparn achieved the position of director of the ANCC Library and he was also Secretary and full member of this prestigious institution that was founded by President Domingo Faustino Sarmiento. In this paper we would like to propose him as the father of Argentinean Scientific Bibliography., Facultad de Ciencias Naturales y Museo

This paper presents the tectonostratigraphic evolution of the Maimara Basin and explores the relationship between the clastic sediments and pyroclastic deposits in the basin and the evolution of the adjacent orogeny and magmatic arc. The sedimentary facies in this part of the basin include, in ascending order, an ephemeral fluvial system, a deep braided fluvial system and a medial to distal ephemeral fluvial system. We interpret that Maimara Formation accumulated in a basin that has developed two stages of accumulation. Stage 1 extended from 7 to 6.4 Ma and included accelerated tectonic uplift in the source areas, and it corresponds to the ephemeral fluvial system deposits. Stage 2, which extended from 6.4 to 4.8 Ma, corresponds to a tectonically quiescent period and included the development of the deep braided fluvial system deposits. The contact between the Maimara and Tilcara formations is always characterized by a regional unconformity and, in the study area, also shows pronounced erosion.Rare earth element and other chemical characteristics of the tuff intervals in the Maimara Formation fall into two distinct groups suggesting the tuffs were erupted from two distinct late Miocene source regions. The first and most abundant group has characteristics that best match tuffs erupted from theGuacha, Pacana and Pastos Grandes calderas, which are located 200 and 230 km west of the study area at 22º-23º30´0 S latitude. The members the second group are chemically most similar to the Merihuaca Ignimbrite from the Cerro Galan caldera 290 km south-southwest of the studied section. The distinctive geochemical characteristics are excellent tools to reconstruct the stratigraphic evolution of the Neogene Maimara basin from 6.4 to 4.8 Ma. Fil: Galli, Claudia Inés. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Coira, Beatriz Lidia Luisa. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta; Argentina Fil: Iglesia Llanos, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina Fil: Prezzi, Claudia Beatriz. 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: Kay, Suzanne Mahlburg. Cornell University; Estados Unidos

The Andean Plateau of NW Argentina is a prominent example of a high-elevation orogenic plateau characterized by internal drainage, arid to hyper-arid climatic conditions and a compressional basin-and-range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run-off and thus subdued surface-process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub-catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U-Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo-landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio-Pliocene Eastern Cordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio-Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid-Pleistocene Climate Transition, caused the present-day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts. Fil: Pingel, Heiko. Universitat Potsdam; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; Argentina Fil: Altenberger, Uwe. Universitat Potsdam; Alemania Fil: Cottle, John. University Of California, Santa Barbara; Fil: Strecker, Manfred R.. Universitat Potsdam; Alemania

Citation: Schildgen, T. F., Robinson, R. A. J., Savi, S., Phillips, W. M., Spencer, J. Q. G., Bookhagen, B., . . . Strecker, M. R. (2016). Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity. Journal of Geophysical Research-Earth Surface, 121(2), 392-414. doi:10.1002/2015jf003607

Foliar impressions were recorded for the first time in the Mio-Pliocene lacustrine sediments at the Quebrada del Toro outcrop (Salta, Argentina). Here we describe a horsetail (Equisetum cf. giganteum L.), ferns (Pteris cf. deflexa Link., Pteris cf. plumula Desv., Circinites pteridoides nov. gen. et nov. sp.) and monocotyledons (Typha cf. latifolia L., Scirpites sp., Poacites sp., Rhizomatites cyperoides nov. gen. et nov. sp., Schoenoplectus californicus, Cyperocarpus sp. 1, Cyperocarpus sp. 2 and Cyperocarpus sp. 3). A few impressions contain insect traces, which correspond with marginal (Phagophytichnus regularis Vasilenko and Phagophytichnus ekowskii van Amerom), non-marginal excisions (Folifenestra polylobata nov. isp.) and piercing and sucking (Circulifolites concavus nov. igen et nov. isp). The inferred paleoenvironment reflects a flora related with water bodies surrounded by open terrestrial areas and limited by a forest. Based on the sedimentological context and plant community composition, we conclude that the plant fossils preserved at the Quebrada del Toro outcrop were deposited in a lagoon environment, comparable to a reed bed. Similar Mio-Pliocene deposits in Northern Argentina were found at the Palo Pintado Formation (Salta, Argentina). The sedimentological characteristics and the paleofloristic similitudes between the Quebrada del Toro outcrop and Palo Pintado Formation support the age assigned to the first fossiliferous location.

The Andes constitute an important orographic barrier in the southern hemisphere, impacting atmospheric circulation, the amount and distribution of rainfall, and Earth-surface processes in a highly asymmetric manner. In the Central Andes of NW Argentina, the Andean Plateau (Puna) and the intermontane basins of the adjacent Eastern Cordillera constitute geological archives that furnish spatiotemporal information on surface uplift and associated paleo-environmental change. Today, rainfall in NW Argentina is focused along the windward flanks of the Eastern Cordillera, while its intermontane basins and the Puna constitute high-elevation regions with strongly reduced rainfall. The present-day influence of these topographic characteristics on precipitation patterns is reflected by systematic changes in the hydrogen stable isotope ratios of meteoric water. Proxy archives from basin strata record past environmental conditions and provide insight into the nature of topographic growth through time. We present 34 new hydrogen isotopic compositions of volcanic glass (δDg), extracted from tuffs interbedded with the sedimentary deposits of three different regions across the eastern Andean margin between ca. 24°S and 25°S latitude. Combined with new zircon U-Pb geochronology, our data show clear spatiotemporal variations in δDg correlating with topographic growth and ensuing orographic effects during the Miocene and Pleistocene. In particular, variations in δDg indicate that the Pastos Grandes (Puna) and the Toro (Eastern Cordillera) basins had attained modern elevations by ca. 8 and 6 Ma, respectively. A strong positive shift in the δDg record of the Toro Basin after 840 ka coincides with deposition of thick fluvial/alluvial conglomerates suggesting orographically induced aridification due to progressive range uplift to the east. Other δDg records from the Eastern Cordillera show similar, but diachronous events emphasizing the importance of regional tectonics for environmental change with implications for the formation of orogenic plateaus.

The extinct South American native ungulates are widely known as a particular evolutionary experiment of mammalian herbivory. Among their representatives, forms with bunodont dentition have received little attention, being usually regarded as primitive and placed in the paraphyletic order “Condylarthra”. Here we describe a new Didolodontidae Saltaodus sirolli gen. et sp. nov. from the Eocene of Lumbrera Formation (Santa Barbara Subgroup) near San Antonio de los Cobres, Salta Province, Argentina. Saltaodus is represented by a small left dentary with a canine alveolus and a brachydont dentition, with p1-2, the roots of p3 and p4-m2. The jaw is broken mesial to the canine alveolus, which is circular and mesially projected. There is only one root for p1 and p2. The specimen has some similarity with North American archaic ungulates but more resembles South American bunodont ungulates. In contrast to Kollpaniinae, Saltaodus presents more separate, slender and higher cusps with well-developed cristids; the talonid basin is wide and not filled by the base of the hypoconid or the distal wall of the metaconid. Several derived character states as compared to Kollpaniinae, such as the more molarized p4, with a clear difference between trigonid and talonid, molars with a talonid equal to or wider than the trigonid, and well separated hypoconid, hypoconulid and entoconid, allow the placement of Saltaodus among Didolodontidae. Saltaodus represents one of the few known small didolodontids (< 5 kg) from the lower latitudes of South America.

The stratigraphic and sedimentologic characteristics of Cenozoic deposits in north‐western Argentina represent important tectono‐sedimentary constraints on the evolution of the Andean foreland basin in this region. This nonmarine unit unconformably rests on the top of the postrift deposits of the middle Eocene Lumbrera Formation (Santa Bárbara Subgroup, Salta Group) or on older deposits. Eocene‐Pliocene paleoenvironmental changes were the direct result of changes in the tectonic setting and accommodation space. This study describes the results of an integrated analysis of the middle‐upper Eocene to Plio‐Pleistocene deposits filling the basins of the Cordillera Oriental. Fluvial deposits associated with different topographic slopes characterize the basins that formed in the Central Andes of north‐western Argentina due to Cenozoic tectonic convergence. The formation of these basins led to the development of continental sedimentary environments, including an ephemeral fluvial system with aeolian dune fields; a sandy braided fluvial system; a playa lake; a sinuous gravelly sandy fluvial system with lagoons; and lagoons and marshes. These basins, which were probably connected during the first stage of their development, are characterized by different subsidence histories, sedimentary paleoenvironmentalevolution patterns, topographic slopes, provenances, and paleocurrentdirections, resulting in different tectono‐sedimentary histories. Fil: Galli, Claudia Inés. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; Argentina Fil: Coira, Beatriz Lidia Luisa. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina

Although Earth's climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from 6.2-5.5 Ma and with the Messinian Salinity Crisis from 6.0-5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from 6.1-5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial "cold" periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO2, thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives. Fil: Amidon, William H.. Middlebury College; Estados Unidos Fil: Fisher, G. Burch. University of Texas at Austin; Estados Unidos. University of California; Estados Unidos Fil: Burbank, Douglas W.. University of California; Estados Unidos Fil: Ciccioli, Patricia Lucia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; Argentina Fil: Gorin, Andrew L.. Middlebury College; Estados Unidos Fil: Silverhart, Perri H.. Middlebury College; Estados Unidos Fil: Kylander Clark, Andrew R.C.. University of California; Estados Unidos Fil: Christoffersen, Michael S.. University of Texas at Austin; Estados Unidos

Foreland basins are important recorders of tectonic and climatic processes in evolving mountain ranges. The Río Iruya canyon of NW Argentina (23° S) exposes ca. 7500 m of Orán Group foreland basin sediments, spanning over 8 Myr of near continuous deposition in the Central Andes. This study presents a record of sedimentary provenance for the Iruya Section in the context of a revised stratigraphic chronology. We use U-Pb zircon ages from six interbedded ash layers and new magnetostratigraphy to constrain depositional ages in the section between 1.94 and 6.49 Ma, giving an average sedimentation rate of 0.93 ± 0.02 (2σ) km Myr−1. We then pair U-Pb detrital zircon dating with quartz trace-element analysis to track changes in sedimentary provenance from ca. 7.6 to 1.8 Ma. Results suggest that from ca. 7.6 to ca. 6.3 Ma, the Iruya watershed did not tap the Salta Group or Neogene volcanics that are currently exposed in the eastern Cordillera and Puna margin. One explanation is that a long-lived topographic barrier separated the eastern Puna from the foreland for much of the mid-late Miocene, and that the arrival of Jurassic-Neogene zircons records regional tectonic reactivation at ca. 6.3 Ma. A second major provenance shift at ca. 4 Ma is marked by changes in the zircon and quartz populations, which appear to be derived from a restricted source region in Proterozoic-Ordovician meta-sediments. Considered in conjunction with the onset of coarse conglomerate deposition, we attribute this shift to accelerated uplift of the Santa Victoria range, which currently defines the catchment's western limit. A third shift at ca. 2.3 Ma records an apparent disconnection of the Iruya with the eastern Puna, perhaps due to defeat of the proto Rio-Iruya by the rising Santa Victoria range. This study is one of the first applications of quartz trace-element provenance analysis, which we show to be an effective complement to U-Pb detrital zircon dating when appropriate statistical methods are applied. Fil: Amidon, William H.. Middlebury College; Estados Unidos Fil: Luna, Elisa Edith. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Arquitectura, Urbanismo y Diseño. Instituto Regional de Planeamiento y Hábitat; Argentina. Middlebury College; Estados Unidos Fil: Fisher, G. Burch. University Of California, Santa Barbara; Fil: Burbank, Douglas W.. University of California; Estados Unidos Fil: Kylander Clark, Andrew R. C.. University of California; Estados Unidos Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Universidad Nacional de Salta; Argentina

Fluvial fill terraces in intermontane basins are valuable geomorphic archives that can record tectonically and/or climatically driven changes of the Earth-surface process system. However, often the preservation of fill terrace sequences is incomplete and/or they may form far away from their source areas, complicating the identification of causal links between forcing mechanisms and landscape response, especially over multi-millennial timescales. The intermontane Toro Basin in the southern Central Andes exhibits at least five generations of fluvial terraces that have been sculpted into several-hundred-meter-thick Quaternary valley-fill conglomerates. New surface-exposure dating using nine cosmogenic 10Be depth profiles reveals the successive abandonment of these terraces with a 100 kyr cyclicity between 75±7 and 487±34 ka. Depositional ages of the conglomerates, determined by four 26Al/10Be burial samples and U–Pb zircon ages of three intercalated volcanic ash beds, range from 18±141 to 936±170 ka, indicating that there were multiple cut-and-fill episodes. Although the initial onset of aggradation at ∼1 Ma and the overall net incision since ca. 500 ka can be linked to tectonic processes at the narrow basin outlet, the superimposed 100 kyr cycles of aggradation and incision are best explained by eccentricity-driven climate change. Within these cycles, the onset of river incision can be correlated with global cold periods and enhanced humid phases recorded in paleoclimate archives on the adjacent Bolivian Altiplano, whereas deposition occurred mainly during more arid phases on the Altiplano and global interglacial periods. We suggest that enhanced runoff during global cold phases – due to increased regional precipitation rates, reduced evapotranspiration, or both – resulted in an increased sediment-transport capacity in the Toro Basin, which outweighed any possible increases in upstream sediment supply and thus triggered incision. Compared with two nearby basins that record precessional (21-kyr) and long-eccentricity (400-kyr) forcing within sedimentary and geomorphic archives, the recorded cyclicity scales with the square of the drainage basin length. Fil: Tofelde, Stefanie. Universitat Potsdam; Alemania. Deutsches Geo Forschungs Zentrum; Alemania Fil: Schildgen, Taylor F.. Universitat Potsdam; Alemania. Deutsches Geo Forschungs Zentrum; Alemania Fil: Savi, Sara. Universitat Potsdam; Alemania Fil: Pingel, Heiko. Universitat Potsdam; Alemania Fil: Wickert, Andrew D.. University of Minnesota; Estados Unidos Fil: Bookhagen, Bodo. Universitat Potsdam; Alemania Fil: Wittmann, Hella. Deutsches Geo Forschungs Zentrum; Alemania Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentina Fil: Cottle, John. University of California; Estados Unidos Fil: Strecker, Manfred R.. Universitat Potsdam; Alemania

The intermontane Quebrada de Humahuaca Basin (Humahuaca Basin) in the Eastern Cordillera of the southern Central Andes of NW Argentina (23°–24°S) records the evolution of a formerly contiguous foreland-basin setting to an intermontane depositional environment during the late stages of Cenozoic Andean mountain building. This basin has been and continues to be subject to shortening and surface uplift, which has resulted in the establishment of an orographic barrier for easterly sourced moisture-bearing winds along its eastern margin, followed by leeward aridification. We present new U–Pb zircon ages and palaeocurrent reconstructions suggesting that from at least 6 Ma until 4.2 Ma, the Humahuaca Basin was an integral part of a largely contiguous depositional system that became progressively decoupled from the foreland as deformation migrated eastward. The Humahuaca Basin experienced multiple cycles of severed hydrological conditions and subsequent re-captured drainage, fluvial connectivity with the foreland and sediment evacuation. Depositional and structural relationships among faults, regional unconformities and deformed landforms reveal a general pattern of intrabasin deformation that appears to be associated with different cycles of alluviation and basin excavation in which deformation is focused on basin-internal structures during or subsequent to phases of large-scale sediment removal. Fil: Heiko, Pingel. Universitat Potsdam. Institut fur Erd- und Umweltwissenschaften. Leibniz Center for Surface Process and Climate Studies; Alemania Fil: Strecker, Manfred R.. Universitat Potsdam. Institut fur Erd- und Umweltwissenschaften. Leibniz Center for Surface Process and Climate Studies; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Cátedra de Mineralogia II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina Fil: Schmitt, Axel K.. University of California. Department of Earth and Space Sciences; Estados Unidos

Rainfall in the central Andes associated with the South American Monsoon and the South American Low-Level Jet results from orographic effects on atmospheric circulation exerted by the Andean Plateau and the Eastern Cordillera. However, despite its importance for South American climate, no reliable records exist that allow decoding the evolution of thresholds and interactions between Andean topography and atmospheric circulation, especially regarding the onset of humid conditions in the inherently dry southern central Andes. Here, we employ multi-proxy isotope data of lipid biomarkers, pedogenic carbonates and volcanic glass from the Eastern Cordillera of NW Argentina and present the first long-term evapotranspiration record. We find that regional eco-hydrology and vegetation changes are associated with initiation of moisture transport via the South American Low-Level Jet at 7.6 Ma, and subsequent lateral growth of the orogen at 6.5 Ma. Our results highlight that topographically induced changes in atmospheric circulation patterns, not global climate change, were responsible for late Miocene environmental change in this part of the southern hemisphere. This suggests that mountain building over time fundamentally controlled habitat evolution along the central Andes. Fil: Rohrmann, Alexander. Universitat Potsdam; Alemania Fil: Sachse, Dirk. Universitat Potsdam; Alemania. German Research Centre for Geosciences; Alemania Fil: Mulch, Andreas. Goethe Universitat Frankfurt; Alemania Fil: Pingel, Heiko. Universitat Potsdam; Alemania Fil: Tofelde, Stefanie. Universitat Potsdam; Alemania Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina Fil: Strecker, Manfred R.. Universitat Potsdam; Alemania

Stable-isotopic and sedimentary records from the orogenic Puna Plateau of NW Argentina and adjacent intermontane basins to the east furnish a unique late Cenozoic record of range uplift and ensuing paleoenvironmental change in the south-central Andes. Today, focused precipitation in this region occurs along the eastern, windward flanks of the Eastern Cordillera and Sierras Pampeanas ranges, while the orogen interior constitutes high-elevation regions with increasingly arid conditions in a westward direction. As in many mountain belts, such hydrologic and topographic gradients are commonly mirrored by a systematic relationship between the oxygen and hydrogen stable isotope ratios of meteoric water and elevation. The glass fraction of isotopically datable volcanic ash intercalated in sedimentary sequences constitutes an environmental proxy that retains a signal of the hydrogen-isotopic composition of ancient precipitation. This isotopic composition thus helps to elucidate the combined climatic and tectonic processes associated with topographic growth, which ultimately controls the spatial patterns of precipitation in mountain belts. However, between 25.5 and 27°S present-day river-based hydrogen-isotope lapse rates are very low, possibly due to deep-convective seasonal storms that dominate runoff. If not accounted for, the effects of such conditions on moisture availability in the past may lead to misinterpretations of proxy-records of rainfall. Here, we present hydrogen-isotope data of volcanic glass (δDg), extracted from 34 volcanic ash layers in different sedimentary basins of the Eastern Cordillera and the Sierras Pampeanas. Combined with previously published δDg records and our refined U-Pb and (U-Th)/He zircon geochronology on 17 tuff samples, we demonstrate hydrogen-isotope variations associated with paleoenvironmental change in the Angastaco Basin, which evolved from a contiguous foreland to a fault-bounded intermontane basin during the late Mio-Pliocene. We unravel the environmental impact of Mio-Pliocene topographic growth and associated orographic effects on long-term hydrogen-isotope records of rainfall in the south-central Andes, and potentially identify temporal variations in regional isotopic lapse rates that may also apply to other regions with similar topographic boundary conditions. Fil: Pingel, Heiko. Universitat Potsdam; Alemania Fil: Mulch, Andreas. Goethe Universitat Frankfurt; Alemania Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Universidad Nacional de Salta; Argentina Fil: Cottle, John. University of California; Estados Unidos Fil: Hynek, Scott A.. Penn State University; Estados Unidos Fil: Poletti, Jacob. University of California; Estados Unidos Fil: Rohrmann, Alexander. Universitat Potsdam; Alemania Fil: Schmitt, Axel K.. Universität Heidelberg; Alemania Fil: Stockli, Daniel F.. University of Texas at Austin; Estados Unidos Fil: Strecker, Manfred R.. Universitat Potsdam; Alemania

In the Central Andes, several studies on alluvial terraces and valley fills have linked sediment aggradation to periods of enhanced sediment supply. However, debate continues over whether tectonic or climatic factors are most important in triggering the enhanced supply. The Del Medio catchment in the Humahuaca Basin (Eastern Cordillera, NW Argentina) is located within a transition zone between subhumid and arid climates and hosts the only active debris‐flow fan within this intermontane valley. By combining 10Be analyses of boulder and sediment samples within the Del Medio catchment, with regional morphometric measurements of nearby catchments, we identify the surface processes responsible for aggradation in the Del Medio fan and their likely triggers. We find that the fan surface has been shaped by debris flows and channel avulsions during the last 400 years. Among potential tectonic, climatic, and autogenic factors that might influence deposition, our analyses point to a combination of several favorable factors that drive aggradation. These are in particular the impact of occasional abundant rainfall on steep slopes in rock types prone to failure, located in a region characterized by relatively low rainfall amounts and limited transport capacity. These characteristics are primarily associated with the climatic transition zone between the humid foreland and the arid orogen interior, which creates an imbalance between sediment supply and sediment transfer. The conditions and processes that drive aggradation in the Del Medio catchment today may provide a modern analog for the conditions and processes that drove aggradation in other nearby tributaries in the past. Fil: Savi, Sara. Universitat Potsdam; Alemania Fil: Schildgen, Taylor F.. Universitat Potsdam; Alemania. German Research Centre for Geosciences; Alemania Fil: Tofelde, Stefanie. Universitat Potsdam; Alemania Fil: Wittmann, Hella. German Research Centre for Geosciences; Alemania Fil: Scherler, Dirk. German Research Centre for Geosciences; Alemania. Freie Universität Berlin; Alemania Fil: Mey, Jürgen. Universitat Potsdam; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Strecker, Manfred R.. Universitat Potsdam; Alemania

El ingeniero de minas sueco Carlos Federico Stubbe (1884-1946), tuvo una importante y a la vez desconocida actuación en nuestro país. Se presentan en este trabajo datos biográficos inéditos producto de una minuciosa búsqueda en archivos y viejos documentos mineros. Stubbe se radicó en la provincia de Tucumán y fue colaborador de Abel Peirano en la década de 1930. Era políglota. Tradujo del sueco el libro del conde Eric von Rosen, Un mundo que se va. Tradujo del alemán los principales trabajos de Federico Schikendantz. Realizó traducciones del inglés para los Cuadernos de Mineralogía y Geología que editaba entonces la Universidad Nacional de Tucumán. Publicó un valioso Vocabulario Minero Antiguo. Dejó inéditos dos libros sobre minería, mineralogía e historia de la minería que se conservan como manuscritos. Reunió una amplia bibliografía que forma el núcleo fundacional de la actual biblioteca del Instituto de Geología y Minería de la Universidad Nacional de Jujuy. En su homenaje se ha propuesto bautizar dicha biblioteca con el nombre de "Ing. Carlos F. Stubbe". Su Vocabulario Minero, la traducción del von Rosen y el hallazgo del yacimiento de fluorita Mina DAL en Catamarca, constituyen tres piedras angulares sobre las que se asienta la valiosa obra de este olvidado minero sueco., We studied here the life and works of Carlos F. Stubbe (1884-1946), a Swedish mining engineer with a very important and unknown activity in northern Argentina. This study includes information related to his biography and published and unpublished papers. This documentation was obtained in different libraries, mining files, documents, journal articles and so on. In the 1930 decade, Stubbe was working in Tucumán as a close collaborator of Dr. Abel Peirano. Stubbe was a polyglot, fluent in Swedish, English, Spanish, French, German and classic languages. He translated the famous work of Eric von Rosen from Swedish to Spanish. Also he translated from German the main papers of Federico Schikendantz; and from English papers related to sedimentology and paleontology. One of his most important works is the book entitled Vocabulario Minero Antiguo. Two books are yet unpublished and are related with mining and its history. He discovered the fluorite vein deposit in the Ancasti hill (Catamarca) that was mined during the 1930' and 1940'. The important library of Stubbe was donated to Jujuy Mining Institute. In his homage, we propose to name as "Eng. Carlos F. Stubbe" the library of Jujuy Mining Institute (IDGYM, UNJU)., Facultad de Ciencias Naturales y Museo

The taxonomy, biostratigraphical and palaeogeographical distribution of the Lower Ordovician graptolite genus Bryograptus is evaluated. Bryograptus is recognized as a distinct triradiate anisograptid with a multiramous, pendent rhabdosome. The species of the genus Bryograptus can be interpreted as shallow water faunal elements with a strongly limited biogeographical distribution to the Atlantic Faunal Realm. Bryograptus is restricted to a narrow interval in the Upper Tremadocian, the Bryograptus Biozone of Scandinavia and South America (Argentina), making it a taxon with a high potential for precise biostratigraphical correlations. The proximal end development can be used to differentiate the genus Bryograptus from other pendent multiramous graptoloid genera with a homoplastic rhabdosome development. Characteristics of the proximal end development and structure easily differentiate these genera in relief specimens, but not in flattened material.

A new genus and species of basal hegetothere mammal, Punahyrax bondesioi, is described from the middle-late? Eocene Geste Formation of northwestern (Catamarca and Salta provinces) Argentina. The new species is based on isolated teeth and mandibles and represents the first well-identified archaeohyracid from northwestern Argentina, and the earliest extra-Patagonian record of the family. It is characterized by its small-size and a short talonid on the molars. Though still poorly documented, this new taxon may provide key-data for the problem of the origin and basal of hegetotheres phylogeny. These fossils show the importance of northwestern Argentina (Puna area) in the early evolution of the extinct order Notoungulata and the poor state of our knowledge there.

The history of the southern central Andes, including the world's second largest plateau and adjacent intermontane basins and ranges of the Eastern Cordillera and the northern Sierras Pampeanas of Argentina and Bolivia, impressively documents the effects of tectonics and topography on atmospheric circulation patterns, the development of orographic barriers, and their influence on erosion and landscape evolution at various timescales. Protracted aridity in the orogen interior has facilitated the creation and maintenance of the Puna-Altiplano plateau. Contraction and range uplift, filling of basins, and possibly wholesale uplift of the plateau increased gravitational stresses in the orogen interior, which caused the eastward migration of deformation into the foreland and successive aridification. The uplift of the Andean orogen has also had a far-reaching influence on atmospheric and moisture-transport patterns in South America. This is documented by the onset of humid climate conditions on the eastern side of the Andes in late Miocene time, which was coupled with the establishment of dramatic precipitation gradients perpendicular to the orogen, and changes in tectonic processes in the Andean orogenic wedge.

The Uquia Formation crops out in the Quebrada de Humahuaca in Jujuy province, Eastern Cordillera, NW Argentina. This unit is composed of a sequence of fluviatile sediments and water-laid air-fall tuff beds; it is approximately 260 m thick and unconformably overlain by Pleistocene conglomerates and Quaternary alluvium. The sediments have been folded into a syncline and broken by several faults that generally trend northwest–southeast. Following Castellanos stratigraphy, we characterize three units (Lower, Middle, and Upper) of the Uquia Formation. Biochronologically, the Lower Unit is assigned to the late Chapadmalalan, the Middle Unit (“Uquian fauna”) to the late Vorohuean and Sanandresian, and the Upper Unit to the Ensenadan. Biostratigraphic evidence provides a calibration of important biochronologic events in the Great American Biotic Interchange (GABI), namely, the first appearances of Erethizon, Hippidion, and proboscideans at 2.5 Ma (late Pliocene) in South America. Geological and paleobiological evidence suggest that during the late Pliocene, the area could have been a wide intermountain valley at 1400–1700 m elevation, with a more humid environment than that of the present day and some wet–dry seasonality that permitted the coexistence of forest and open areas. Uquian mammals also indicate that northwestern Argentina and the Pampean region have represented distinct biogeographical areas since at least the late Pliocene.

Sedimentary basin fills along the windward flanks of orogenic plateaus are valuable archives of paleoenvironmental change with the potential to resolve the history of surface uplift and orographic barrier formation. The intermontane basins of the southern Central Andes contain thick successions of sedimentary material that are commonly interbedded with datable volcanic ashes. We relate variations in the hydrogen isotopic composition of hydrated volcanic glass (δDg) of Neogene to Quaternary fills in the semiarid intermontane Humahuaca Basin (Eastern Cordillera, northwest Argentina) to spatiotemporal changes in topography and associated orographic effects. δD values from volcanic glass in the basin strata (–117‰ to –98‰) show two main trends that accompany observed tectonosedimentary events in the study area. Between 6.0 and 3.5 Ma, δDg values decrease by ∼17‰; this is associated with surface uplift in the catchment area. After 3.5 Ma, δDg values show abrupt deuterium enrichment, which we associate with (1) the attainment of threshold elevations for blocking moisture transport in the basin-bounding ranges to the east, and (2) the onset of semiarid conditions in the basin. Such orographic barriers throughout the eastern flanks of the Central Andes have impeded moisture transport into the orogen interior; this has likely helped maintain aridity and internal drainage conditions on the adjacent Andean Plateau. Fil: Pingel, Heiko. Universität Potsdam; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina Fil: Mulch, Andreas. Goethe Universitat Frankfurt; Alemania. Biodiversität und Klima Forschungszentrum; Alemania Fil: Rohrmann, Alexander. Universität Potsdam; Alemania Fil: Sudo, Masafumi. Universität Potsdam; Alemania Fil: Strecker, R.. Universität Potsdam; Alemania

The stratigraphic and sedimentological characteristics of the Payogastilla Group represent important tectono-sedimentary constraints on the evolution of the Andean foreland basin in northwestern Argentina. This nonmarine unit unconformably rests on top of the post-rift deposits of the middle Eocene Lumbrera Formation of the Santa Bárbara Subgroup (Salta Group). Eocene-Pliocene paleoenvironmental changes are a direct result of the tectonic settings and accommodation space. Sequential stratigraphic analysis of the paleoenvironment of the Los Colorados Formation strata indicates the presence of three third-order sequences. Each sequence comprises a low-accommodation systems tract (LAST) and a highaccommodation systems tract (HAST). Substantial tectonic activity from the middle to upper Miocene is represented by Angastaco Formation strata that contain a shallow, gravel-braided fluvial system associated with gravity flows, with thicknesses of 4550 m (Calchaquí River) to 1500 m (Tonco). This activity marked the depocenter of the Angastaco basin. The development of a basal unconformity and the erosion of the Los Colorados Formation suggest a renewed uplift of the source area. Changes in the fluvial systems indicate an increase of the accommodation space. To obtain better temporal constraints on the basin evolution, new UePb ages on zircons from five pyroclastic airfall and two sedimentary levels were determined. A substantial environmental change in the upper Miocene (10e5 Ma) is associated with three episodes of tectonic uplift that are reflected in variations in the sedimentation rates of the Palo Pintado Formation. A reactivated Pliocene tectonic uplift is recorded in alluvial fans that originated from the east. Fil: Galli, Claudia Ines. Universidad Nacional de Jujuy. Facultad de Ingenieria; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina Fil: Coira, Beatriz Lidia Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina. Universidad Nacional de Salta; Argentina Fil: Reynolds, James. Brevard College; Estados Unidos Fil: Matteini, Massimo. Universidade Do Brasilia; Brasil Fil: Hauser, Natalia. Universidade Do Brasilia; Brasil

Globally, changes in stable isotope ratios of oxygen and hydrogen (δ18Oand δD) in the meteoric water cycle result from distillation and evaporation processes. Isotope fractionation occurs when air masses rise in elevation, cool, and reduce their water-vapor holding capacity with decreasing temperature. Assuch, δ18Oand δDvalues from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges. Based on 234 stream-water samples, wedemonstrate that areas experiencing deep convective storms in the eastern south?central Andes (22?28◦S) do not show the commonly observed relationship between δ18Oand δDwith elevation. These convective storms arise from intermontane basins, where diurnal heating forces warm air masses upward, resulting in cloudbursts and raindrop evaporation. Especially at the boundary between the tropical and extra-tropical atmospheric circulation regimes where deep-convective storms are very common (∼26◦to 32◦N andS), the impact of such storms may yield non-systematic stable isotope-elevation relationships as convection dominates over adiabatic lifting of air masses. Because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation, linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions, and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells. Fil: Rohrmann, Alexander. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania Fil: Strecker, Manfred R.. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania Fil: Bookhagen, Bodo. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania. University of California at Los Angeles; Estados Unidos Fil: Mulch, Andreas. Biodiversity and Climate Research Centre; Alemania. Goethe Universität Frankfurt. Institut für Geowissenschaften; Alemania Fil: Sachse, Dirk. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania. GFZ German Research Centre for Geosciences; Alemania Fil: Pingel, Heiko. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina Fil: Schildgen, Taylor F.. Universität Potsdam. Institut für Erd- und Umweltwissenschaften; Alemania Fil: Montero Lopez, Maria Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Bio y Geociencias del Noroeste Argentino; Argentina

We present a teleseismic P and S receiver function study using data from a temporary passive-source seismic array in the southernmost Puna plateau and adjacent regions. The P receiver function images show the distribution of crustal thickness and Vp/Vs ratio for this area. Over much of the southern Puna plateau, the crustal thickness is 50–55 km, whereas to the west a thicker crust (∼60 to 75 km) is observed beneath much of the Andean volcanic arc region. From the Puna southward, there is little obvious change in the crustal thickness across the border of the plateau (south of 28°S). The crust is seen to progressively thin towards the east in the Pampean Ranges where it is 35–40 km thick. The southern Puna plateau is characterized overall by a low crustal Vp/Vs ratio (less than 1.70), implying a felsic crustal composition. An anomalously high Vp/Vs ratio of 1.87 is observed beneath the Cerro Galan volcanic center, in the region where a prominent crustal low-velocity zone identified below ∼10 km depth probably extends into the lower crust. The crustal thickness determined under the Cerro Galan area (59 km) is close to that of the rest of the southern Puna. The prominent high Vp/Vs ratio and low-velocity zone beneath the Galan region implies the presence of a zone of partial melt or a magma chamber is consistent with hypothesis calling for lithospheric delamination beneath the Galan caldera. A widespread crustal low-velocity layer observed beneath much of the southern Puna, correlates well with crustal low-velocity anomalies observed by teleseismic tomography. The lithosphere–asthenosphere boundary beneath the array can be clearly observed by both P and S receiver functions at depths of 70–90 km in agreement with previous studies suggesting a thin lithosphere beneath the high elevated plateau. The mantle transition zone discontinuities appear at expected depths. Fil: Heit, B.. Deutsches GeoForschungsZentrum; Alemania Fil: Bianchi, M.. Deutsches GeoForschungsZentrum; Alemania. Universidade de Sao Paulo; Brasil Fil: Yuan, X.. Deutsches GeoForschungsZentrum; Alemania Fil: Kay, S. M.. Cornell University; Estados Unidos Fil: Sandvol, E.. University Of Missouri; Estados Unidos Fil: Kumar, P.. Deutsches GeoForschungsZentrum; Alemania. NGRI; India Fil: Kind, R.. Deutsches GeoForschungsZentrum; Alemania. Freie Universität Berlin; Alemania Fil: Alonso, Ricardo Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina. Universidad Nacional de Salta; Argentina Fil: Brown, L.. Cornell University; Estados Unidos Fil: Comte, D.. Universidad de Chile; Chile

Upper Precambrian-Lower Cambrian sequences in the Tucuman, Salta and Jujuy provinces, NW Argentina, comprise sandstone, slate, conglomerate and black limestone (Las Tienditas/Volcan Fms.) with abundant Vendian/Tommotian trace fossils in the clastic facies rocks. The Precordillera basin, San Juan province, represents a continuous carbonate sequence belonging to the Lower to Middle Cambrian La Laja Fm. The Pie-de-Palo Range, Pampean Range, characterized by carbonates intercalated with greenschist/amphibolite facies metaclastic rocks, forms a part of the Precordillera basement. The δ13C values in carbonates of the Las Tienditas Fm. show a gradual decrease from the base (+3.4 ‰PDB) to the top with a minimum of −1.6‰ observed at ∼15m from the top, the latter having a higher clay content. Carbonates in a 700m thick section within La Laja Fm. is marked by a slightly positive δ13C values at the base (marly) with a negative anomaly (−2.0‰) at ∼20 m above, followed by a small positive anomaly (+0.5‰) ∼100 m from the base. All the values above this point are around −0.5‰ with a negative anomaly (−2.0‰) recorded at ∼240m above the base. Seawater87Sr/86Sr values define a non-monotonic increase (0.70870–0.71082) through the carbonates in Las Tienditas Fm. while the La Laja Fm carbonates vary from 0.70926 to 0.71030, with higher values at the base. C and Sr isotopes, thus suggest that the Las Tienditas carbonates record the Precambrian-Cambrian transition (∼15m from the top of studied section). The same is also evident at ∼30 m from the base of the La Laja Fm. The narrow range of δ13C variation (−1.4 to +1.3‰) and87Sr/86Sr in the 0.709–0.710 range for the Caucete Group carbonates of the Pie-de-Palo Range, although unequivocally, appear to be in consonance with a Vendian to Tommotian age, reinforced by the presence of the trace fossils Didymaulichnus and Gordia.

This paper deals with sedimentologic and diagenetic aspects of the evaporitic fades of the Sijes Formation (Miocene, central Andes, NW Argentina), which contains the largest known hydroboracite reserves in the world. In outcrop, the sulfate minerals are secondary gypsum and minor anhydrite, and the borate minerals are hydroboracite with subordinate inyoite and colemanite, and some ulexite. In the Monte Amarillo Member of the Sijes Formation it is possible to distinguish two coeval, shallow lacustrine subbasins, in which the gypsum accumulated in the margins and the hydroboracite in the centers, the intermediate zones being characterized by mixed gypsum-hydroboracite layers. In the depositional sequence, primary gypsum (gypsarenite) and syndepositional anhydrite, in association with limited amounts of calcium borates (colemanite, inyoite) precipitated first, followed by hydroboracite (calcium/magnesium borate). Alternations of gypsum and hydroboracite layers also formed. Hydroboracite is mainly a primary mineral, although it replaced some gypsum under synsedimentary conditions. The formation of colemanite, which occurred during early diagenesis, is linked to the precipitation of calcium sulfates (gypsum and anhydrite), whereas inyoite coexists with both calcium sulfates and magnesium-bearing borates. Transformations among the various borate minerals during burial diagenesis were not detected. Primary gypsum was transformed into anhydrite from early diagenesis to moderate burial diagenesis. The boron source of these deposits seems to be related to the volcanic/hydrothermal activity in the central Andes during the Miocene. Fil: Ortí, Federico. Universidad de Barcelona; España Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina

Lithium-rich brine within the sub-surface of the Salar del Hombre Muerto (SHM) salt pan in the Andes of northwestern Argentina has a chemical and isotopic composition which is consistent with Li derived from several sources: the modern halite saturated lagoon, Li-rich salts and brines formed recently, and dissolution of halite which precipitated from ancient saline lakes. SHM lies in the closed basin that includes part of the massive Cerro Galán caldera which is drained by the Río los Patos, which is responsible for 90% of surface runoff into the salar. The low Li isotope composition, +3.4‰, of this river is consistent with significant contributions of geothermal spring water. As water drains through the volcaniclastic deposits which cover a large proportion of the basin, Li removal, as indicated by decreasing Li/Na, occurs but without significant isotope fractionation. This indicates a mechanism of surface sorption onto smectite or ferrihydrite rather than Li incorporation into octahedral structural sites of clays. These observations suggest that conditions in this high altitude desert have limited the dilution of hydrothermal spring water as well as the formation of clay minerals, which jointly have allowed the Li resource to accumulate rapidly. Changes in climate on a multi-millennial time scale, specifically in the hydrologic budget, have resulted in solute accumulation rates that have been variable through time, and decoupled Li and Na fluxes. Inflow to the salar under modern conditions has high Li/Na (7.9 × 10−3 by wt) with δ7Li indistinguishable from basement rocks (−0.3‰ to +6.4‰), while under pluvial climate conditions the Li/Na of the saline lake was 40 times lower than the modern lagoon (0.1–0.3 × 10−3 compared to 10.6–13.4 × 10−3) with slightly higher δ7Li, +6.9‰ to +12.3‰, reflecting the uptake of 6Li into secondary minerals which formed under a wetter climate. Fil: Godfrey, L. V.. Cornell University. Department of Earth and Atmospheric Sciences; Estados Unidos. Rutgers University. Institute of Marine and Coastal Sciences; Estados Unidos Fil: Chan, L. H.. Louisiana State University. Department of Geology and Geophysics; Estados Unidos Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Cátedra de Mineralogia II; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentina Fil: Lowenstein, T. K.. State University of New York at Binghamton. Department of Geological Sciences and Environmental Studies; Estados Unidos Fil: Mcdonough, W. F.. University of Maryland. Department of Geology; Estados Unidos Fil: Houston, J.. Stuart Lodge; Reino Unido Fil: Li, J.. State University of New York at Binghamton. Department of Geological Sciences and Environmental Studies; Estados Unidos Fil: Bobst, A. . State University of New York at Binghamton. Department of Geological Sciences and Environmental Studies; Estados Unidos Fil: Jordan, T. E.. Cornell University. Department of Earth and Atmospheric Sciences; Estados Unidos

An array of 74 seismological stations was deployed in the Argentine Puna and adjacent regions for a period of two years. The aim is to investigate the seismic structure in the crust and upper mantle in order to address fundamental questions regarding the processes that form, modify and destroy continental lithosphere and control lithospheric dynamics in this part of the Central Andes. This portion of the Central Andes is an ideal locale to address these questions given that there is geologic evidence that there has been recent lower crustal and mantle lithospheric delamination. We performed a teleseismic P wave tomography study using seismic events at both teleseismic and regional distances. The tomographic images show the presence of a number of positive and negative anomalies in this region. The most prominent of these anomalies corresponds to a lowvelocity body, located in the crust, in the center of the array (approximately at 27°S, 67°W) between the Cerro Peinado volcano, the Cerro Blanco caldera and the Farallon Negro in the east. This anomaly (southern Puna Magmatic Body) is flanked by high velocities on the west and the east respectively. On the west, this high velocity block might be related to the subducted Nazca plate. On the east, it coincides with the position of the Hombre Muerto basin in the crust and could be indicating an area of lithopheric delamination where we detected a high velocity block at 100 km depth on the eastern border of the Puna plateau. This block might be related to a delamination event in an area with a thick crust of Paleozoic metamorphic rocks from the Eastern Cordillera. We observed lower velocities in the Puna lithosphere that could be indicative of magma chambers derived from the ascent of fluids and melts from the top of the subducted plate probably induced by delamination. Beneath the oceanic Nazca plate, a low-velocity zone can be observed at depths greater than 200 km. The origin of this low velocity anomaly remains unclear but it could be caused by portions of asthenospheric material in the uppermost mantle. The position of this low velocity zone is in agreement with previous observations in the same area that have suggested the presence of a hot asthenospheric mantle upwelling induced by slab flattening. Keywords: Central Andes, Puna plateau, teleseismic tomography, arc and back-arc volcanoes, velocity anomalies, lithospheric structure. Fil: Bianchi, M.. Deutsches GeoForschungsZentrum; Alemania Fil: Heit, B.. Deutsches GeoForschungsZentrum; Alemania Fil: Jakovlev, A.. Institute of Geology; Rusia Fil: Yuan, X.. Deutsches GeoForschungsZentrum; Alemania Fil: Kay, S. M.. Cornell University; Estados Unidos Fil: Sandvol, E.. University Of Missouri; Estados Unidos Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina Fil: Coira, Beatriz Lidia Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Instituto de Geología y Minería; Argentina Fil: Brown, L.. Cornell University; Estados Unidos Fil: Kind, R.. Deutsches GeoForschungsZentrum; Alemania Fil: Comte, D.. Universidad de Chile; Chile

[1] The central Andean retroarc thrust belt is characterized by a southward transition at ∼22°S in structural style (thin-skinned in Bolivia, thick-skinned in Argentina) and apparent magnitude of Cenozoic shortening (>100 km more in the north). With the aim of evaluating the abruptness and cause of this transition, we conducted a geological and geo-thermochronological study of the Cachi Range (∼24–25°S), which is a prominent topographic feature at this latitude. Our U-Pb detrital zircon results from the oldest exposed rocks (Puncoviscana Formation) constrain deposition to mainly Cambrian time, followed by major, Cambro-Ordovician shortening and ∼484 Ma magmatism. Later, Cretaceous rift faults were locally inverted during Cenozoic shortening. Coupled with previous work, our new (U-Th)/He zircon results require 8–10 km of Miocene exhumation that was likely associated with fault-propagation folding within the Cachi Range. After Miocene shortening, displacement on sinistral strike-slip faults demonstrates a change in stress state to a non-vertically orientedσ3. This change in stress state may result from an increase in gravitational potential energy in response to significant crustal thickening and/or lithospheric root removal. Our finding of localized Cenozoic shortening in the Cachi Range increases the estimate of the local magnitude of shortening, but still suggests that significantly less shortening was accommodated south of the thin-skinned Bolivian fold-thrust belt. Our results also underscore the importance of the pre-existing stratigraphic and structural architecture in orogens in influencing the style of subsequent deformation.

Kinematic analysis of ∼ 1500 fault-slip measurements from the Puna plateau and adjacent foreland of northwestern Argentina suggests that two regional kinematic regimes characterize late Cenozoic deformation: a thrust phase with ∼WNW-ESE shortening and subvertical extension followed by a strike-slip phase with ∼ENE-WSW shortening and ∼NNW-SSE extension. Radiometric dating combined with field relationships demonstrate that thrust faulting started by 13 Ma and lasted, at least locally, until 1 Ma, and that strike-slip faulting started by 2 Ma and is still active. The shortening direction of the thrust phase, which accounts for most of the Andean shortening, differs from the coeval plate tectonic convergence direction and probably cannot be explained by later oroclinal bending. Paleostructural control of deformation kinematics and/or strike-slip faulting along the thermally weakened volcanic arc might explain the Mio-Pliocene shortening direction. The subhorizontal extension direction of the strike-slip phase is evident at all elevations studied, suggesting that local body forces do not drive it. A decrease in South America-Nazca plate convergence rate and/or complex three-dimensional effects, possibly including kinematic variation with depth in the crust, might provide a satisfactory explanation.

The geographic extent, interconnectedness and chronology of the Miocene "Paranaense" epeiric seaway have been the subject of considerable debate. Understanding the timing and location of this marine incursion is significant for documenting sea level changes, paleoclimatic changes, and surface uplift or subsidence. Stable isotope analyses of carbonate strata in the flat-slab segment of the Sierras Pampeanas and high Andean Cordillera, previously purported to be of marine origin, provide evidence that the Paraná seaway did not inundate this portion of west and central Argentina. No unambiguously marine facies or isotopic signatures were recognized for five representative stratigraphic units: the Saguión Formation ESE of Salinas Grande in Córdoba Province; Anta Formation in the Quebrada de la Yesera and Lerma Valley of Salta Province; Del Buey and Del Abra Formations within the Famatina Ranges, La Rioja Province; and Chinches Formation in the Manantiales foreland basin in the Frontal Cordillera, San Juan Province. Paleontologic and lithologic features in support of a marine origin are reconsidered herein. Instead, a lacustrine origin is inferred for these formations, their contemporaneity perhaps related to concurrent global climate conditions and broad tectonic setting. Until more substantive evidence of marine deposition is found, we reject correlation of these units with the Paraná seaway, preserved in the Chaco-Pampean Plain subsurface, and discourage mapping of the seaway as extending into the central Sierras Pampeanas or Andean foreland. Our findings suggest the Miocene Andean foreland was elevated above sea level although it remained as a largely flat-lying area west of the Pampas and Chaco plains, which were inundated by the Paraná seaway. Fil: Ruskin, Brian G.. Cornell University; Estados Unidos 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: Hoke, Gregory D.. Syracuse University; Estados Unidos Fil: Jordan, Teresa E.. Cornell University; Estados Unidos Fil: Astini, Ricardo Alfredo. 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: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

[1] The northwest Argentine Andes constitute a premier natural laboratory to assess the complex interactions between isolated uplifts, orographic precipitation gradients, and related erosion and sedimentation patterns. Here we present new stratigraphic observations and age information from intermontane basin sediments to elucidate the Neogene to Quaternary shortening history and associated sediment dynamics of the broken Salta foreland. This part of the Andean orogen, which comprises an array of basement-cored range uplifts, is located at ∼25°S and lies to the east of the arid intraorogenic Altiplano/Puna plateau. In the Salta foreland, spatially and temporally disparate range uplift along steeply dipping inherited faults has resulted in foreland compartmentalization with steep basin-to-basin precipitation gradients. Sediment architecture and facies associations record a three-phase (∼10, ∼5, and

Orogenic plateaus are extensive, high-elevation areas with low internal relief that have been attributed to deep-seated and/or climate-driven surface processes. In the latter case, models predict that lateral plateau growth results from increasing aridity along the margins as range uplift shields the orogen interior from precipitation. We analyze the spatiotemporal progression of basin isolation and filling at the eastern margin of the Puna Plateau of the Argentine Andes to determine if the topography predicted by such models is observed. We find that the timing of basin filling and reexcavation is variable, suggesting nonsystematic plateau growth. Instead, the Airy isostatically compensated component of topography constitutes the majority of the mean elevation gain between the foreland and the plateau. This indicates that deep-seated phenomena, such as changes in crustal thickness and/or lateral density, are required to produce high plateau elevations. In contrast, the frequency of the uncompensated topography within the plateau and in the adjacent foreland that is interrupted by ranges appears similar, although the amplitude of this topographic component increases east of the plateau. Combined with sedimentologic observations, we infer that the low internal relief of the plateau likely results from increased aridity and sediment storage within the plateau and along its eastern margin. Fil: Strecker, M. R.. Universitat Potsdam; Alemania Fil: Alonso, Ricardo Narciso. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina Fil: Bookhagen, B.. University of California; Estados Unidos Fil: Carrapa, B.. University of Wyoming; Estados Unidos Fil: Coutand, Isabelle. Universite Lille; Francia Fil: Hain, M. P.. Universitat Potsdam; Alemania Fil: Hilley, G. E.. Universite Lille; Francia Fil: Mortimer, E.. Leeds University; Reino Unido Fil: Schoenbohm, L.. Ohio State University; Estados Unidos Fil: Sobel, E. R.. Universitat Potsdam; Alemania