Memorias del III Congreso Internacional de Lectura y Escritura. Lectura y Escritura: Ejes de una Escuela de Calidad. Quito, 6, 7 y 8 de junio de 2007

El III Congreso Internacional de Lectura y Escritura “Lectura y escritura: ejes de una educación de calidad” fue pensado como un espacio de debate plural en torno a la pedagogía de la lectura y de la escritura, encaminado a la construcción colectiva de propuestas innovadoras que aporten al mejoramiento de la calidad educativa. Cerca de doscientos docentes, directivos e investigadores de la educación de todo el país participaron de las experiencias y aprendizajes desarrollados en el marco del Proyecto CECM, se vincularon a las últimas investigaciones sobre la didáctica de la lectura y escritura y reconocieron que la enseñanza signifi cativa de estas competencias comunicativas puede refutar el “determinismo socio-cultural” con el que tradicionalmente se ha explicado el fracaso de los y las estudiantes de los sectores sociales más desprotegidos: niño pobre – escuela pobre – futuro pobre transformarlo a: niño pobre – escuela de calidad – futuro de calidad. La programación del Congreso incluyó el dictado de dos conferencias magistrales que se reproducen y de las conferencias realizadas.

Petrological parameters of sands and sandstones from DSDP and ODP holes in arc-related areas

Detrital modes for 524 deep-marine sand and sandstone samples recovered on circum-Pacific, Caribbean, and Mediterranean legs of the Deep Sea Drilling Project and the Ocean Drilling Program form the basis for an actualistic model for arc-related provenance. This model refines the Dickinson and Suczek (1979) and Dickinson and others (1983) models and can be used to interpret the provenance/tectonic history of ancient arc-related sedimentary sequences. Four provenance groups are defined using QFL, QmKP, LmLvLs, and LvfLvmiLvl ternary plots of site means: (1) intraoceanic arc and remnant arc, (2) continental arc, (3) triple junction, and (4) strike-slip-continental arc. Intraoceanic- and remnant-arc sands are poor in quartz (mean QFL%Q < 5) and rich in lithics (QFL%L > 75); they are predominantly composed of plagioclase feldspar and volcanic lithic fragments. Continental-arc sand can be more quartzofeldspathic than the intraoceanic- and remnant-arc sand (mean QFL%Q values as much as 10, mean QFL%F values as much as 65, and mean QmKP%Qm as much as 20) and has more variable lithic populations, with minor metamorphic and sedimentary components. The triple-junction and strike-slip-continental groups compositionally overlap; both are more quartzofeldspathic than the other groups and show highly variable lithic proportions, but the strike-slip-continental group is more quartzose. Modal compositions of the triple junction group roughly correlate with the QFL transitional-arc field of Dickinson and others (1983), whereas the strike-slip-continental group approximately correlates with their dissected-arc field.

(Table 5) Quaternary paleoproductivity of organic carbon in oceans based on DSDP cores

By analogy with the present-day ocean, primary productivity of paleoceans can be reconstructed using calculations based on content of organic carbon in sediments and their accumulation rates. Results of calculations based on published data show that primary productivity of organic carbon, mass of phosphorus involved in the process, and content of phosphorus in ocean waters were relatively stable during Cenozoic and Late Mesozoic. Prior to precipitation on the seafloor together with biogenic detritus, dissolved phosphorus could repeatedly be involved in the biogeochemical cycle. Therefore, only less than 0.1% of phosphorus is retained in bottom sediments. Bulk phosphorus accumulation rate in ocean sediments is partly consistent with calculated primary productivity. Some epochs of phosphate accumulation also coincide with maxima of primary productivity and minima of the fossilization coefficient of organic carbon. The latter fact can testify to episodes of acceleration of organic matter mineralization and release of phosphorus from sediments leading to increase in the phosphorus reserve in paleoceans and phosphate accumulation in some places.