Abstract:

Con el objetivo de dilucidar relaciones temporo-espaciales y controles entre intervalos carbonáticos y silicoclásticos dentro de sucesiones cíclicas marinas, en este trabajo se presenta un estudio facial, paleoambiental y secuencial de alta resolución del Miembro Superior de la Formación Mulichinco en el subsuelo del extremo austral de la Provincia de Mendoza (yacimiento Cañadón Amarillo). La unidad posee entre 65 y 80 m de potencia en la región y se caracteriza por una recurrente alternancia de escala métrica de intervalos silicoclásticos y otros con dominancia de componentes carbonáticos. El estudio se basa en el análisis sedimentológico de detalle de cuatro testigos de corona que abarcan la totalidad del intervalo estudiado y en total representan 240 m de espesor. En el Miembro Superior de la Formación Mulichinco se identificaron e interpretaron cinco asociaciones de facies, tres dominadas por depósitos silicoclásticos y dos con dominio de componentes carbonáticos. Las asociaciones silicoclásticas se depositaron en un sistema marino dominado por procesos de olas de buen tiempo y tormenta y representan un espectro continuo de condiciones de sedimentación desde ambientes someros de shoreface inferior, pasando por un ambiente intermedio o zona de transición, hasta regiones ubicadas por debajo de la base de olas de tormenta u offshore. Por su parte las asociaciones de facies mixtas y calizas puras representan el desarrollo de un sistema de rampa con alta producción de materiales carbonáticos, en donde se reconocen condiciones de alta energía o rampa somera (grainstones y packstones oolíticoesqueletales), y condiciones más distales de rampa media, con generación de depósitos con alta participación de fango micrítico (wackestones, packstones y floatstones esqueletales). El análisis de diseños estratales, superficies clave y distribución espacial de las asociaciones de facies indica que estos dos sistemas de acumulación no co-existieron, sino que se reemplazaron cíclicamente debido a variaciones de alta frecuencia del nivel relativo del mar. De esta manera los ciclos de pequeña escala (3 a 18 m de espesor) reconocidos en el Miembro Superior de la Formación Mulichinco se interpretan como secuencias de alta frecuencia limitadas por superficies transgresivas de erosión y están típicamente compuestas por hemiciclos transgresivos relativamente delgados y dominados por componentes carbonáticos, seguidos por hemiciclos silicoclásticos más potentes, los cuales representan fenómenos de progradación de una línea de costa. La superficie no erosiva que los limita representa una superficie de máxima inundación. Los resultados de este trabajo contribuyen a avanzar en la caracterización de los niveles productivos alojados en esta sucesión cíclica. Se definieron tipos de facies con buenas perspectivas de constituir reservorio y sus características principales (geometría, espesor, conectividad, heterogeneidades internas), y fue posible elaborar un modelo con carácter predictivo dentro del yacimiento, que explica desde un punto de vista genético, cuál sería la posición más probable de dichas facies dentro de una secuencia de alta frecuencia. La incorporación de estos elementos a un modelado geológico estático puede finalmente contribuir a un mejor y más eficiente desarrollo del campo y sus niveles reservorio.

The presence of carbonate strata within siliciclastic-dominated marine successions (i.e. mixed carbonate-siliciclastic successions) poses serious challenges for palaeoenvironmental reconstructions and reservoir characterization, and unambiguous interpretations can emerge only when the spatial vs. temporal relationship between carbonate production and siliciclastic input is well understood. This study integrates sedimentology and high-resolution sequence stratigraphy in order to better understand the temporal/spatial relationships and controls in the origin of a Lower Cretaceous, mixed carbonatesiliciclastic succession in the subsurface of the Neuquén Basin, west-central Argentina (Figs. 1, 2). This mixed succession, so-called Upper Member of the Mulichinco Formation, accumulated in a shallow, epeiric sea during third-order highstand conditions (Fig. 3), and is presently widely distributed in the central part of the basin, both in outcrops and subsurface (Schwarz et al., 2009; Schwarz et al., 2011). The study area, covering an area of about 80 km2, is located in the Cañadón Amarillo hydrocarbon field (Fig. 4), where this unit has been in production since the 1970’s. This study is based on a detailed description and interpretation of four cored wells (three of them covering the entire unit), complemented with calibrated well-log suites from additional 22 wells (Fig. 5). The Upper Member of the Mulichinco Formation (65-80 m thick) has a cyclic alternation of relatively thick (up to 16 m) siliciclastic packages and thinner carbonate-dominated intervals (Fig. 6). Three facies associations were identified within the siliciclastic packages, and they are inferred to represent shoreface, offshore-transition, and offshore settings in an open marine system influenced by storm- and fair-weather waves. The lower-shoreface facies association (Fig. 7) is composed of amalgamated, siliciclastic sandstone beds (with minor contribution of carbonate particles) mostly having hummocky cross-stratification, horizontal lamination or ripple cross-lamination. Bioturbation varies from low to high and the trace fossil suite (Arenicolites, Gyrochortes, Palaeophycus, Ophiomorpha, Skolithos y ?Macaronichnus) is interpreted to represent an Skolithos ichnofacies (MacEachern et al., 2007). The offshore-transition facies association groups intensely bioturbated muddy sandstones and less bioturbated (i.e. better preserved) sandstone-rich heterolithics (Fig. 8), with occasional medium-bedded sandstone beds (< 15 cm thick) having HCS and rippled tops. Siliciclastics largely dominate within these sediments, but bioclasts (mostly from oysters) can be common locally. The assemblage of trace fossils (Planolites, Palaeophycus, Thalassinoides, Teichichnus, Phycosiphon, Ophiomorpha, Schaubcylindrichnus y Asterosoma) is attributed to represent a Proximal Cruziana ichnofacies (MacEachern and Bann, 2008), and, together with the sediments, reflect a stormdominated offshore-shoreface transition, between the storm and fair-weather wave bases (Reading & Collinson, 1996). In turn, the offshore facies association comprises mostly massive or laminated mudstones, as well as mudstone-dominated heterolithics. In the latter, very thin-bedded siltstone beds with wavy tops are abundant, likely reflecting the distal ends of storm-related flows. Carbonate-dominated intervals are composed of two facies associations that collectively are inferred to represent subenvironments within a carbonate ramp, namely shallow (inner) and middle sectors of it. The shallow-ramp facies association is characterized by cross-bedded ooid-skeletal grainstones/packstones, with subordinated skeletal rudstones and packstones (Fig. 10). Bioclasts derived mostly from mollusks and echinoids, whereas terrigenous material is less than 25%. These sediments deposited in open-marine high-energy settings, likely shoals and intershoals areas (Rankey y Reeder, 2011; Christ et al., 2012). In contrast, the middle-ramp facies association is composed of muddominated textures, mostly skeletal wackestones and floatstones (Fig. 11). They are massive, but argillaceous seams might create a nodular aspect. Bioclasts from epibenthic (oysters) and endobenthic bivalves, as well as from serpulids and echinoids are dominant, but glauconite and intraclasts are locally abundant. Compared to the previous association, these sediments were deposited in lower energy and deeper parts of the ramp. The nature of key stratigraphic surfaces, facies associations distribution and analysis of stacking patterns within this cyclic carbonate/siliciclastic succession suggest that the siliciclastic- and carbonate-dominated depositional systems were not coeval, but replaced over time. Correlation panels show that individual carbonate and siliciclastic hemicycles extend across the entire area and lateral transition between them were not recorded (Figs. 12, 13). Carbonate packages are invariably bounded by sharp, erosive surfaces (Fig. 14a,b), which are interpreted to represent transgressive ravinement surfaces (Swift, 1968; Nummedal and Swift, 1987). Facies associations in these hemicycles suggest a deepening-upward trend, whereas in the overlying siliciclastic packages the stratal patterns indicate normal (i.e. not forced) regressive conditions (Fig. 15). Therefore, the seven small-scale cycles (plus two incomplete cycles) recorded in the Upper Member of the Mulichinco Formation (3-18 m thick) are interpreted to represent high-frequency sequences (nomenclature following Zecchin and Catuneanu, 2013), comprising relatively thin, transgressive, carbonate-rich hemicycles and thicker, siliciclastic regressive hemicycles (Fig 16). The non-erosive boundary between both hemicycles (Fig. 14c) could correlate with the maximum flooding surface (Van Wagoner et al., 1990), or being slightly younger, as it reflects enough terrigenous supply to dilute carbonate productivity (Abbot, 1997). In this context, it is considered equivalent of a downlap surface (Fig 16). These high-frequency sequences were most likely controlled by short-term, low-amplitude, relative sea-level changes, and the thickness of transgressive hemicycles could have been influenced by carbonate productivity and/or rate of transgression. The results of this study provide with a more accurate reservoir characterization of this mixed (and complex) succession. Two reservoir-type facies associations were identified, namely the lowershoreface and shallow-ramp facies associations. The understanding of key reservoir attributes, such as geometry, thickness, connectivity and internal heterogeneity were improved with this study. Additionally, the findings of this work provided with a high-resolution sequence-stratigraphic model that help predicting the occurrence of the reservoirtype facies within a high-frequency sequence. The integration of all these elements within a geological model could contribute to define for example the most efficient development strategy for the reservoir horizons (e.g. vertical versus horizontal wells) which would, eventually, impact in the recovery factor of the field.

Author affiliation: Schwarz, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina

Author affiliation: Álvarez Trentini, Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina

Author affiliation: Valenzuela, Marta E.. YPF S.A; Argentina

Abstract:

This study presents experimental results from a flooding test series performed at reservoir conditions for five high-porosity Cretaceous onshore chalks from Denmark, Belgium and the USA, analogous to North Sea reservoir chalk. The chalks are studied in regard to their chemo-mechanical behaviour when performing tri-axial compaction tests while injecting brines (0.219 mol/L MgCl 2 or 0.657 mol/L NaCl) at reservoir conditions for 2–3 months (T = 130 ∘C ; 1 PV/d). Each chalk type was examined in terms of its mineralogical and chemical composition before and after the mechanical flooding tests, using an extensive set of analysis methods, to evaluate the chalk- and brine-dependent chemical alterations. All MgCl 2-flooded cores showed precipitation of Mg-bearing minerals (mainly magnesite). The distribution of newly formed Mg-bearing minerals appears to be chalk-dependent with varying peaks of enrichment. The chalk samples from Aalborg originally contained abundant opal-CT, which was dissolved with both NaCl and MgCl 2 and partly re-precipitated as Si-Mg-bearing minerals. The Aalborg core injected with MgCl 2 indicated strongly increased specific surface area (from 4.9 m 2/g to within 7–9 m 2/g). Mineral precipitation effects were negligible in chalk samples flooded with NaCl compared to MgCl 2. Silicates were the main mineralogical impurity in the studied chalk samples (0.3–6 wt%). The cores with higher SiO 2 content showed less deformation when injecting NaCl brine, but more compaction when injecting MgCl 2-brine. The observations were successfully interpreted by mathematical geochemical modelling which suggests that the re-precipitation of Si-bearing minerals leads to enhanced calcite dissolution and mass loss (as seen experimentally) explaining the high compaction seen in MgCl 2-flooded Aalborg chalk. Our work demonstrates that the original mineralogy, together with the newly formed minerals, can control the chemo-mechanical interactions during flooding and should be taken into account when predicting reservoir behaviour from laboratory studies. This study improves the understanding of complex flow reaction mechanisms also relevant for field-scale dynamics seen during brine injection.

Author affiliation: Andersen, P.Ø.. University of Stavanger; Noruega

Author affiliation: Wang, W.. University of Stavanger; Noruega

Author affiliation: Madland, M.V.. University of Stavanger; Noruega

Author affiliation: Zimmermann, U.. University of Stavanger; Noruega

Author affiliation: Korsnes, R. I.. University of Stavanger; Noruega

Author affiliation: Bertolino, Silvana Raquel Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina

Author affiliation: Minde, M.. University of Stavanger; Noruega. International Research Institute of Stavanger; Noruega

Author affiliation: Schulz, B.. TU Bergakademie Freiberg; Alemania

Author affiliation: Gilbricht, S.. TU Bergakademie Freiberg; Alemania

Abstract:

Continental carbonates are rich in paleoclimatic, paleoenvironmental, and paleontologic information. While carbonate sedimentation-precipitacion mechanisms have been described for different continental environments and in extensional basins there are still uncertainties that existing facies models fail to answer. The Triassic Cerro de las Cabras and Cerro Puntudo Formations are alluvial-fluvial-lacustrine sequences that represent a part of the sedimentary infilling in two sub-basins of the Cuyana basin during the early stages of the Triassic rift in west-central Argentina. Previous work has provided absolute dates, confirming that deposits are coeval (Anisian) allowing a comparative study of carbonate sedimentation in an extensional tectonic context. The research addresses the description and origin of freshwater carbonate deposits and their surrounding siliciclastic sediments therefore identifying the major factors that controlled carbonate precipitation in specific areas of the Cuyana rift, the characterization of the paleohydrology, and an understanding of the evolution in space and time of the carbonate sedimentary systems. Sedimentologic studies of the Cerro de las Cabras Formation reveal an ephemeral, playa-lake depositional system with subaerial exposure and pedogenesis. The unit is an aggradational succession that corresponds to the evaporative facies association type, diagnostic of underfilled lake basins. However, the lakes model links underfilled lakes with persistently closed surface hydrology, though groundwater supply may be open in this case. In the Cerro de las Cabras Formation evidence for biota in the microbialitic limestones indicates microbially-induced precipitation of carbonate. Sedimentologic studies of the Cerro Puntudo Formation reveal an alkaline playa-lake system fed by groundwater and ephemeral surface-water input. The unit is an aggradational-minor progradational succession, pointing to a fluctuating profundal facies association suggesting a balanced-filled lake type. The Cerro Puntudo paleolake contains a microbialite assemblage that reflects an aquatic paleoecosystem with a simple trophic network. These two synchronous, lacustrine depositional systems were influenced by tectonics (synrift geography and lithology of drainage area) and climate (surface water and groundwater input). Provenance and hydrology are key controls in carbonate accumulation in continental rift basins that must be included in future models. Comparison with successions of different rift basins suggest that application of these concepts to other rift basins will aid in developing new carbonate sedimentation models for freshwater limestones in extensional settings.

Author affiliation: Benavente, Cecilia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

Author affiliation: Mancuso, Adriana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

Author affiliation: Cabaleri, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotópica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; Argentina

Author affiliation: Gierlowski-kordesch, Elizabeth. Ohio University; Estados Unidos

Abstract:

Continental carbonates are rich in palaeoclimatic, palaeoenvironmental and palaeontological information. While carbonate accumulation mechanisms have been described for many types of continental environments, especially in extensional basins, there are still uncertainties that existing facies models fail to address. The Triassic Cerro de las Cabras and Cerro Puntudo formations are alluvial–fluvial–lacustrine sequences that represent a part of the sedimentary infill of two sub-basins of the Cuyana Basin during the early stages of the Triassic rift in west-central Argentina. Previous work has provided absolute dates, confirming that these deposits are coeval (Anisian) allowing a comparative study of carbonate sedimentation in an extensional tectonic context. The description and origin of freshwater carbonate deposits and their surrounding siliciclastic sediments in specific areas of the Cuyana rift, gives insight into the major factors that control carbonate precipitation in all rift basins, including the characterization of the palaeohydrology and the importance of provenance. The Cerro de las Cabras Formation represents an ephemeral, playa-lake depositional system with subaerial exposure and pedogenesis. Its aggradational succession corresponds to the evaporative facies association lake type, diagnostic of underfilled lake basins where persistently closed surface hydrology can lead to thick evaporites. However, this formation lacks thick evaporites and has microbialitic limestones, pointing to an open groundwater supply. The Cerro Puntudo Formation represents an alkaline playa-lake system fed by groundwater and ephemeral surface-water input. The unit is an aggradational–minor progradational succession, pointing to a fluctuating profundal facies association, suggesting a balanced-filled lake type. These two synchronous, lacustrine depositional systems were influenced by tectonics and climate. Provenance and hydrology are key controls in carbonate accumulation in continental rift basins that must be included in future facies models for continental carbonates. Comparison with other rift basins suggests that application of lake-type characterizations coupled with palaeohydrology and provenance patterns will aid in developing new sedimentation models for freshwater limestones in extensional settings.

Author affiliation: Benavente, Cecilia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

Author affiliation: Mancuso, Adriana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina

Author affiliation: Cabaleri, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentina

Author affiliation: Gierlowski Kordesch, Elizabeth. Ohio University; Estados Unidos

Abstract:

Tradicionalmente, se consideró que la marcada aridez regional que caracterizó al Holoceno Medio en los Andes Tropicales habría generado el abandono de la región por parte de los grupos humanos. Sin embargo, la evidencia paleoambiental obtenida en algunas localidades indica que el período presentó una elevada heterogeneidad temporal y espacial que habría hecho posible sostener la ocupación humana del área. De igual modo, en años recientes se ha incrementado la señal arqueológica para el período en la Puna argentina y chilena. Dada la nueva evidencia disponible, resulta imprescindible comprender y modelar la variabilidad espacio-temporal de la estructura de recursos disponibles para abordar el estudio de las relaciones entre las condiciones ambientales y los patrones organizativos de los grupos humanos que habitaron la Puna a lo largo del Holoceno. En este trabajo presentamos los primeros resultados paleoambientales obtenidos de una secuencia sedimentaria ubicada en la Quebrada de Inca Cueva, en la Puna de Jujuy, a partir del análisis del contenido de materia orgánica y carbonatos en sedimentos en 65 muestras que abarcan un rango temporal de ca. 1300 años (7000 – 5700 años AP). A su vez, esta información nos impulsó a reevaluar el registro arqueológico del Holoceno Medio en sitios cercanos -i.e. Inca Cueva Cueva 1, 4 y 7, Alero Pintoscayoc 1 y Alero Tomayoc. Los resultados apuntan a que la quebrada de Inca Cueva habría exhibido las características de un humedal productivo relativamente estable en el lapso temporal analizado. Dichas características resultan coherentes con la evidencia arqueológica, la cual indica que la quebrada presentó diversas y dilatadas ocupaciones humanas durante gran parte del Holoceno Medio. Esto nos permite postular a modo de hipótesis que Inca Cueva pudo haber funcionado como una localidad “resiliente”, manifestando un potencial elevado para la ocupación y explotación humana, aún en momentos híper-áridos del Holoceno.

Traditionally, the regional aridity that characterized the Mid-Holocene across the Tropical Andes was considered to have triggered the human abandonment of the region. However, paleoenvironmental evidence recovered in some localities indicates that the period presented a high temporal and spatial heterogeneity that would have enabled human occupation of the area. Similarly, in recent years the archaeological signal for the period in the Puna Argentina and Chile has increased significantly. In view of the new evidence available, it is essential to understand and model the spatio-temporal variability of past resource structure during this period, in order to fully understand the links between environmental conditions and organizational patterns of human groups that inhabited the Puna. In this paper, we present the first paleoenvironmental results obtained from the study of a sedimentary sequence located in the Quebrada de Inca Cueva (Puna de Jujuy), through the analysis of organic matter and carbonate content in 65 sediment samples, spanning ca. 1300 years (7000-5700 years BP). This information compelled us to reassess of the archaeological record from the Mid-Holocene in nearby -ie Inca Cave 1, 4 and 7, Alero Pintoscayoc 1, and Alero Tomayoc. The results suggest that Inca Cueva could have been a relatively stable and productive wetland during the analyzed period. These characteristics are consistent with the archaeological evidence, which indicates that the area presented diverse and persistent human occupations during much of the Mid-Holocene. This allows us to hypothetize that Inca Cueva may have functioned as a "resilient" locality, showing a high potential for human occupation and exploitation, even in hyper-arid periods within the Holocene.

Author affiliation: Pirola, Malena. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Morales, Marcelo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina

Author affiliation: Yacobaccio, Hugo Daniel. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

It has come to our attention that in our paper published in The Journal of Chemical Thermodynamics (J. Chem. Thermodyn. 69 (2014) 193-?200), the density values for the composition x1 = 0.8031 of (n-octane (1) + p-xylene (2)) binary system are misprinted in table 6 for all temperatures evaluated. This also affects figure 2b and table 8 for the modified Tait equation coefficients.

Author affiliation: Gayol, Ana. Universidad de Vigo; España

Author affiliation: Martini, Raquel Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Nacional de Córdoba; Argentina

Author affiliation: Andreatta, Alfonsina Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; Argentina. Universidad Tecnológica Nacional. Facultad Regional San Francisco; Argentina

Author affiliation: Legido, José Luis. Universidad de Vigo; España

Author affiliation: Casás, Lidia. Université de Pau et des Pays de l’Adour; Francia

Abstract:

Marbles from the province of Córdoba (Argentina) have been used as aggregates in concrete; however, there is little information about their potential reactivity and interaction with the cement paste. Recently, the alkali-carbonate reactivity of dolomitic to calcitic marbles from this province was determined by standardized methods (ASTM C1293, ASTM C586, CSA A23.2-26A) and a modification of the Chinese Accelerated Mortar Bar Method (M-CAMBT) using a single aggregate size fraction (2.5–5.0 mm). Although all samples behaved as non-reactive some expansion was recorded, especially in the M-CAMBT method. In this work microstructural and chemical studies were carried out by stereomicroscopy, polarizing microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) on mortar bars tested by the M-CAMBT method. Dedolomitization was detected in all dolomitic and calc-dolomitic marbles being more accentuated in the samples with more dolomite. This process is characterized by the development of different zones in the cement–aggregate interface that differ in texture and chemical composition and are similar to the zones described by other authors in dolomitic limestones typically associated with the so-called alkali–carbonate reaction. Therefore, the presence and distribution of dedolomitization appears not to be related to the texture of the aggregates but to the amount of dolomite in the rock. The low expansions recorded were associated with relict strained quartz and possibly with fine-grained phlogopite in the matrix of the rocks, which have acted as silica sources for the development of secondary silicates of variable composition (±Ca ± Na ± K ± Mg ± Al) and microfissures as a result of the alkali–silica reaction rather than the non-expansive dedolomitization process.

Author affiliation: Locati, Francisco. 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

Author affiliation: Falcone, Ruben Dario. Laboratorio de Entrenamiento Multidisciplinario para la Investigación Tecnológica; Argentina. Universidad Nacional de La Plata; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina

Author affiliation: Marfil, Silvina Andrea. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. 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

Abstract:

Hypothesis: Biopolymer–CaCO3 hybrid microparticles exposed to hydrolytic enzymes can provide new surface tailorable architectures. Soluble Alginate Lyase hydrolyzed alginate chains exposed on microparticle surface are generating considerable matrix changes. The change of porosity and surface to volume ratio is expected to influence absorption of drugs, thereby affecting controlled release profiles. The developed hybrid system potentially shows interesting properties for lung drug administration. Experimental: Hybrid microparticles were developed by colloidal co-precipitation of CaCO3 in presence of biopolymers: alginate (Alg) or Alg–High Methoxylated Pectin (HMP), followed by treatment with Alginate Lyase (AL). Surface architectures were observed by SEM. The increase in area to volume ratio was confirmed by BET isotherms. Also, enzymatic changes were elucidated by biophysical methods (EDAX, DSC, FTIR, XRD) and determination of the total carbohydrates content. Levofloxacin (a fluoroquinolone antibiotic) as model drug was incorporated by absorption. The drug release profile and the antimicrobial activity of the microparticles were tested against Pseudomonas aeruginosa. Findings: After enzyme treatment, microspheres showed 4 μm diameter and increased porosity. While CaCO3–Alg microspheres resulted in a rougher surface, CaCO3–Alg–HMP ones exhibited “nano-balloon” patterns on surface. Both AL-treated microparticles showed up to 3 and 7 times higher Levofloxacin encapsulation than no treated ones. Microparticles showed controlled drug release profiles and enhanced antimicrobial effect. The present work demonstrates a significant progress in the development of new carriers with potential application for lung infections treatment.

Author affiliation: Islan, German Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Author affiliation: Cacicedo, Maximiliano Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Author affiliation: Bosio, Valeria Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Author affiliation: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Abstract:

The mechanism of the reaction between amines with dimethyl carbonate (DMC) has been investigated. Whereas in the absence of bases, they give methylation and carboxymethylation reactions without selectivity (BAl2 and BAc2 mechanisms, respectively), in the presence of bases, the BAc2 mechanism prevails. The carbamate already formed reacts further with DMC via the BAl2 mechanism to give the corresponding N-methyl derivative. Such pronounced double selectivity has been explained in terms of Pearson’s Hard–Soft Acid-Base (HSAB) theory. Accordingly, N-methylcarbamates have been prepared from primary aliphatic and aromatic amines, either at reflux temperature of DMC (90 °C) or at 230 °C in autoclave. The reaction can be carried out in one step or through the isolation of the carbamate and the subsequent methylation reaction with DMC. This method is the direct synthesis, in high yield and selectivity, of secondary N-methylamines from the corresponding primary amines.

Author affiliation: Tundo, Pietro. Universita' Ca' Foscari Di Venezia; Italia

Author affiliation: Bressanello, Salimo. Universita' Ca' Foscari Di Venezia; Italia

Author affiliation: Loris, Alessandro. Universita' Ca' Foscari Di Venezia; Italia

Author affiliation: Sathicq, Angel Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina

Abstract:

The carbonatic sequence of the Calabozo Formation (Lower Callovian) developed in southwestern Gondwana, within the northern area of the Neuquén basin, and is widespread in thin isolated outcrops in southwestern Mendoza province, Argentina. This paper describes the facies, microfacies and geochemical-isotopic analysis carried out in five studied localities, which allowed to define the paleoenvironmental conditions of a homoclinal shallow ramp model, highly influenced by sea level fluctuations, where outer, mid and inner ramp subenvironments were identified. The outer ramp subenvironment was only recognized in the south of the depocenter and is characterized by proximal outer ramp facies with shale levels and interbedded mudstone and packstone layers. The mid ramp subenvironment is formed by low energy facies (wackestone) affected by storms (packstones, grainstones and floatstones). The inner ramp subenvironment is the most predominant and is characterized by tidal flat facies (wackestones, packstones and grainstones) over which a complex of shoals (grainstones and packstones) dissected by tidal channels (packstone, grainstones and floatstones) developed. In the north area, protected environment facies were recorded (bioturbated wackestones and packstones). The vertical distribution of facies indicates that the paleoenvironmental evolution of the Calabozo Formation results from a highstand stage in the depocenter, culminating in a supratidal environment, with stromatolitic levels interbedded with anhydrite originated under restricted water circulation conditions due to a progressive isolation of the basin. δ13C and δ18O values of the carbonates of the Calabozo Formation suggest an isotopic signature influenced by local palaeoenvironmental parameters and diagenetic overprints. The δ13C and δ18O oscillations between the carbonates of the different studied sections are related with lateral facies variations within the carbonate ramp accompanied with dissimilar reactivities in relation to diagenetic fluids. The δ18O values of all sections exhibit a rather broad scatter which may be attributed to diagenesis and recrystallisation while the carbon isotopic composition has been less affected by those processes. Carbon isotope system has best retained the primary isotopic signal and δ13C values (0–3.9‰) are within the Callovian isotope range. The 87Sr/86Sr ratios of the bulk carbonates of El Plomo creek, La Vaina creek and Potimalal River sections are in agreement with the Callovian seawater Sr-isotope curve.

Author affiliation: Armella, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentina

Author affiliation: Cabaleri, Nora Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentina

Author affiliation: Cagnoni, Mariana Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentina

Author affiliation: Panarello, Hector Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotopica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotopica; Argentina