Examinando por Autor "Martínez, F."

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    Deciphering the Late Paleozoic–Cenozoic Tectonic History of the Inner Central Andes Forearc: An Update From the Salar de Punta Negra Basin of Northern Chile
    (Frontiers Media S.A., 2022-01) Martínez, F.; Parra, M.; Gonzalez, R.; López, C.; Patiño, A.; Muñoz, B.; Robled, F.; Sobel, E.; Glodny, J.
    We integrated new and existing geological, geochronological, thermochronological, and two-dimensional (2D) seismic data from the Salar de Punta Negra Basin to define the Late Paleozoic–Cenozoic tectonic evolution of the inner Andean forearc of northern Chile more precisely. Our results indicate that this region experienced early Late Paleozoic–Mesozoic crustal extension, creating several basement half-graben structures bounded by east- and west-dipping master faults. These extensional basins were filled by Upper Permian to Jurassic volcanic and sedimentary (continental and marine) syn-rift deposits. The genesis of these structures is related to the early breakup of the western Gondwana continent and the development of the large Tarapacá Basin in northern Chile and southern Perú. Subsequently, Late Cretaceous to Paleocene contraction occurred, which led to the tectonic inversion of the pre-existing rift system and the uplift of the Paleozoic–Mesozoic syn-rift deposits. Seismic data show that Upper Cretaceous and Paleocene synorogenic deposits accumulated along and over inversion anticlines, recording the initial contraction and marking the change from an extensional to a contractional tectonic setting. During the final episodes of basin inversion, crustal shortening was accommodated by the Eocene to recent basement reverse faulting accompanied by the rapid exhumation of basement pre-rift blocks, which served as the principal sources for the sediments that filled the pre-Andean basins during the Late Cenozoic. Finally, the exhumed basement pre-rift blocks and the reverse faults compartmentalized the contractional intermontane basins, which constitute the main low topographic relief of the inner forearc of northern Chile.
  • Miniatura
    Ítem
    Synthesis, thermal behavior, and aggregation in aqueous solution of poly(methyl methacrylate)-b-poly(2-hydroxyethyl methacrylate)
    (2014 Sociedad Chilena de Química, 2013) Acevedo, B.; Martínez, F.; Olea, A. F.
    ABSTRACT Amphiphilic block copolymers of poly(methyl methacrylate) PMMA and poly(2-hidroxyethyl methacrylate) PHEMA were synthesized by a two-step atom transfer radical polymerization (ATRP). Copolymers with various degrees of polymerization and different relative block sizes were obtained. The structure of the resulting polymers have been characterized and verified by FT-IR and 1H-NMR, molecular weight were determined by size exclusion chromatography analyses. The thermal properties of these polymers were investigated by differential scanning calorimetry DSC and thermogravimetric analysis TGA. The glass transition temperature of mono halogenated PMMA increases from 116 °C to 123 °C with increasing molecular weight, whereas the glass transition temperature of block copolymers depends slightly on polymer structure. The derivatives of TGA curves indicate that thermal degradation occurs in one stage. The self-assembly of PMMA-b-PHEMA in aqueous solution have been investigated by fluorescence probing methods. The critical micelle concentrations are in the range 10-6 - 10-7 M. The micropolarity sensed by pyrene is higher than in aggregates formed by block copolymers based on polystyrene. Keywords: Block copolymers, glass transition temperature, thermogravimetric analysis, critical micelle concentration, fluorescence probing methods.