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The Planchón-Peteroa Volcanic Complex (PPVC) is located in the Transitional Southern Volcanic Zone of the Andean Ridge. Structural control of the main NNE-striking El Fierro fault system (EFFS) over the volcanic activity has been commonly assumed, although a paucity of evidence remains. The aim of this paper is to explore the relationship between the local stress field, the superficial structural setting and the geothermal fluid flow paths related to the volcanic complex. To conduct the structural analysis, this work combines remote sensing determination of lineaments, recognition of fracture patterns, with the inversion of kinematic indicators on outcrop scale faults, to finally evaluate the role of the local stress field over the 2D slip and dilation tendencies of the recognized structures. Mesoscale morphostructural lineaments present three main directions: ~E-W, ~NE-SW, and ~NW-SE. Major lineaments develop inflections, giving rise to left bends between the NW-SE to E-W along the strike, compartmentalized by ~ NNE trending lineaments. Strike-slip fault solutions with an ENE-WSW to NE-SW oriented shortening axis were obtained from fault-slip data analysis. The inversion of fault kinematic indicators constrains a Quaternary to recent strike-slip regime, with a ~ENE-WSW trending σ1, and a subvertical σ2. Under the defined local stress field, ~NE-SW and ~WNW-ESE oriented structures have high slip tendency, while those spanning from NE-SW to E-W are prone to dilate. Our analysis suggests that these transverse structures exert first-order controls on the location of Vergara Pass Hill, and Peñón River and Azufre River Valleys hydrothermal manifestations. It seems that intersection zones with submeridian structures, as EFFS, increase structural damage and facilitate hot fluid migration. Circulation would profit the most from ~ENE-WSW and ~NW-SE striking outcrop-scale faults and fractures associated with the damage zones. Fil: Vigide, Nicolás Carlos. 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 "Don Pablo Groeber"; Argentina Fil: Yagupsky, Daniel Leonardo. 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 "Don Pablo Groeber"; Argentina Fil: Barcelona, Hernan. 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 "Don Pablo Groeber"; Argentina Fil: Agusto, Mariano Roberto. 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 "Don Pablo Groeber"; Argentina Fil: Caselli, Alberto Tomás. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The aim of this paper is to study the provenance of Late Cretaceous sandstones deposited along the south flank of the Golfo San Jorge Basin. For this purpose, detrital modes of three hundred thirty-seven sandstone samples collected in the Mina del Carmen, Bajo Barreal, and Cañadón Seco Formations were studied in ten oil fields. According to the modal composition of the sandstones, six petrofacies were defined allowing the identification of not only principal, but also secondary provenance areas. The QVM and VQM petrofacies are more than 20% metamorphic, sedimentary, and polycrystalline quartz clasts (Lm + Ls + Qpg > 20%), evidencing a secondary signal of basement supply masked by a predominant volcanic provenance. The petrofacies VP and VF are characterized by Lm + Ls + Qpg 20%.), which indicate a supply of sediment from volcanic terrains and scarce derivation of materials from basement rocks. Based on the plagioclase/k-feldspar ratio, the VF petrofacies is interpreted to be dominated by the supply of sand grains from the Andean volcanic-arc, while VP is supposed have originated through the erosion of intermediate volcanic rock outcroppings in the Macizo del Deseado. Finally, both the VQ and QV petrofacies show Lm + Ls + Qpg

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 combined application of sedimentary facies and palynofacies analyses constitutes a valuable method for paleoenvironmental andpaleoclimatic reconstructions, especially in continental strata in which fossil information is scarce or absent. In this paper, we present anintegrated model based on this methodology for the Eocene lacustrine rocks of the Lumbrera Formation in northwest Argentina. The newdata contribute to the understanding of the evolution of the final post-rift stage of the Salta Group in northwest Argentina.The lacustrine deposits of the Lumbrera Formation are named Faja Verde I and Faja Verde II. In the Alemanı ́a area, the Faja Verde IIconsists of green claystones and mudstones interbedded with sandstones and deposited in a perennial lake and fluvio-dominated deltacomplex. In addition, there are two major cycles that are separated by a flooding surface. The basal cycle is a retrogradational parasequenceset, and the upper cycle is a progradational parasequence set. The palynofacies analysis and organic matter analytical data (TOC and PyrolysisRock-Eval) of each sedimentary facies are closely related to the dynamics of the depositional environment. Proximal prodelta (Palynofaciesassociation I), distal prodelta (Palynofacies association II), lacustrine (Palynofacies association III), and interdistributary bay fill(Palynofacies association IV) subenvironments are differentiated. Each is characterized by a definitive relationship of phytoclasts, amorphous,palynomorphs, fluorescence index, quality, and quantity of the organic matter. The variation of occurrence of thePediastrum–Botryococcusalgae reflects fluctuations in the level of water related to identified cycles of shallowing. El uso combinado del análisis de facies sedimentarias y palinofacies brinda una herramienta válida para las reconstrucciones paleoambientales y paleoclimáticas de una cuenca, especialmente en secuencias continentales donde la información a partir del registro fósiles escasa o está ausente. En este trabajo se presenta un modelo sedimentario que surge de la integración de ambos métodos llevado a cabo en las rocas de origen lacustre de la Formación Lumbrera en el noroeste argentino. Finalmente los nuevos datos contribuyen al conocimiento general sobre la evolución del estadio final de post-rift del Grupo Salta en el noroeste argentino. La Formación Lumbrera (Eoceno) argentino presenta en su tercio inferior una intercalación de depósitos lacustres, denominados Faja Verde I y Faja Verde II. En la localidad de Alemania la Faja Verde II, esta ́formada por arcilitas y limolitas verdes y grises, con intercalaciones de areniscas, depositados en un lago perenne y delta fluvio-dominado. Se reconocieron dos ciclos estratigráficos mayores separados por una superficie de inundación. El ciclo basal formado por parasecuencias con arreglo retrogradante y el superior integrado por parasecuencias progradantes. El análisis de palinofacies y los datos analíticos de materia orgánica (COT y Pirólisis Rock-Eval) de cada facies sedimentaria identificada, esta ́en estrecha relación con la dinámica del ambiente deposicional. Se diferenciaron los siguientes subambientes: Prodelta proximal (asociación de palinofacies I), Prodelta distal (asociacio ́n de palinofacies II), lacustre (asociación de palinofacies III) y bahía interdistributaria (asociación de palinofacies IV) cada uno caracterizado por una determinada relación de fitoclastos, amorfos, palinoformos, índice de fluorescencia, calidad y cantidad de la materia orgánica. Ha sido observado que las variaciones en la relación de las algas Pediastrum–Botryococcus reflejan fluctuaciones del nivel de agua relacionadas con los ciclos de somerización identificados. Fil: del Papa, Cecilia Eugenia. 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: Quattrocchio, Mirta Elena. 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