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Pena Presas Montse - One of the best experts on this subject based on the ideXlab platform.
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El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria)
'Universitat Politecnica de Valencia', 2016Co-Authors: Cantero Sandoval Almudena, Pena Presas MontseAbstract:[EN] Access to classic texts by students is still a challenge in Spanish Language and Literature lessons during Compulsory Secondary Education. At the same time, literature for children and young adults is getting more and more present in this educational stage. The present didactic proposal intends to exemplify how —by means of workshops to be developed throughout an academic year— a picture book can motivate and make the reading of different Spanish canonical works more accessible. Some examples of that would be: The Life of Lazarillo de Tormes, The Celestine, Fuenteovejuna, Stanzas about the Death of his Father or crea-tions by the writer Garcilaso de la Vega. Likewise, by using the values emerging from the texts and, therefore, by showing their timelessness, these workshops are to have an impact on individuals formation and on trying to achieve an inclusive school and thence, society.[EN] El acceso a los textos clásicos por parte del alumnado sigue siendo un reto en las clases de lengua y literatura de la Educación Secundaria Obligatoria. Al mismo tiempo, es cada vez mayor la presencia que la literatura infantojuvenil adquiere en esta etapa educativa. Esta propuesta didáctica quiere ejemplificar como, a través de la formulación de talleres, un álbum ilustrado puede motivar y hacer más accesible la lectura de diferentes obras canónicas como son el Lazarillo de Tormes, La Celestina, Fuenteovejuna, Coplas por la muerte de su padre o las creaciones de Garcilaso de la Vega. Igualmente, utilizando los valores que emanan los diferentes textos y, por lo tanto, mostrando su atemporalidad, estos talleres incidirán en la formación de individuos para lograr una escuela y, por tanto, una sociedad inclusiva.Cantero Sandoval, A.; Pena Presas, M. (2016). El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria). Lenguaje y Textos. (43):89-96. doi:10.4995/lyt.2016.5939.SWORD89964
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El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria)
'Universitat Politecnica de Valencia', 2016Co-Authors: Cantero Sandoval Almudena, Pena Presas MontseAbstract:[EN] Access to classic texts by students is still a challenge in Spanish Language and Literature lessons during Compulsory Secondary Education. At the same time, literature for children and young adults is getting more and more present in this educational stage. The present didactic proposal intends to exemplify how —by means of workshops to be developed throughout an academic year— a picture book can motivate and make the reading of different Spanish canonical works more accessible. Some examples of that would be: The Life of Lazarillo de Tormes, The Celestine, Fuenteovejuna, Stanzas about the Death of his Father or crea-tions by the writer Garcilaso de la Vega. Likewise, by using the values emerging from the texts and, therefore, by showing their timelessness, these workshops are to have an impact on individuals formation and on trying to achieve an inclusive school and thence, society.[EN] El acceso a los textos clásicos por parte del alumnado sigue siendo un reto en las clases de lengua y literatura de la Educación Secundaria Obligatoria. Al mismo tiempo, es cada vez mayor la presencia que la literatura infantojuvenil adquiere en esta etapa educativa. Esta propuesta didáctica quiere ejemplificar como, a través de la formulación de talleres, un álbum ilustrado puede motivar y hacer más accesible la lectura de diferentes obras canónicas como son el Lazarillo de Tormes, La Celestina, Fuenteovejuna, Coplas por la muerte de su padre o las creaciones de Garcilaso de la Vega. Igualmente, utilizando los valores que emanan los diferentes textos y, por lo tanto, mostrando su atemporalidad, estos talleres incidirán en la formación de individuos para lograr una escuela y, por tanto, una sociedad inclusiva.Cantero Sandoval, A.; Pena Presas, M. (2016). El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria). Lenguaje y Textos. (43):89-96. doi:10.4995/lyt.2016.5939.SWORD899643ANÓNIMO. (2006). Lazarillo de Tormes. Madrid: Alfaguara.Blanco, R. (1999). Hacia una escuela para todos y con todos. Boletín del Proyecto Principal de Educación para América Latina y el Caribe, 48, 55-72.De Rojas, F. (2006). La Celestina. Madrid: Alfaguara.García Padrino, J. (1992). Literatura infantil y educación. En: CERRILLO, P. y GARCÍA PADRINO, J .(Coords.). Literatura infantil y ense-anza de la literatura, pp.13-25. Cuenca: Ediciones de la Universidad de Castilla-La Mancha.Green, M. (2005). Liberar la imaginación. Ensayos sobre educación, arte y cambio social. Barcelona: Graó.Manrique, J. (1993). Coplas a la muerte de su padre. Madrid: Castalia.Núñez Delgado, M. P. (2001). Comunicación y expresión oral. Hablar, escuchar y leer en Secundaria. Madrid: Narcea.Silva-Díaz, C. (2003). "¡Qué libros más raros! Construcción y evaluación de un instrumento para describir las variaciones metaficcionales en el álbum. Anuario de Investigación en Literatura Infantil y Juvenil, 1, 167-189
Cantero Sandoval Almudena - One of the best experts on this subject based on the ideXlab platform.
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The Picture Book as a Bridge between Canon Literature and the Inclusive School: A Teaching Proposal for Secondary Education
'Universitat Politecnica de Valencia', 2016Co-Authors: Cantero Sandoval Almudena, Pena Presas MontserratAbstract:El acceso a los textos clásicos por parte del alumnado sigue siendo un reto en las clases de lengua y literatura de la Educación Secundaria Obligatoria. Al mismo tiempo, es cada vez mayor la presencia que la litera-tura infantojuvenil adquiere en esta etapa educativa. Esta propuesta didáctica quiere ejemplificar como, a través de la formulación de talleres, un álbum ilustrado puede motivar y hacer más accesible la lectura de diferentes obras canónicas como son el Lazarillo de Tormes, La Celestina, Fuenteovejuna, Coplas por la muerte de su padre o las creaciones de Garcilaso de la Vega. Igualmente, utilizando los valores que emanan los diferentes textos y, por lo tanto, mostrando su atemporalidad, estos talleres incidirán en la formación de individuos para lograr una escuela y, por tanto, una sociedad inclusiva.Access to classic texts by students is still a challenge in Spanish Language and Literature lessons during Compulsory Secondary Education. At the same time, literature for children and young adults is getting more and more present in this educational stage. The present didactic proposal intends to exemplify how —by means of workshops to be developed throughout an academic year— a picture book can motivate and make the reading of different Spanish canonical works more accessible. Some examples of that would be: The Life of Lazarillo de Tormes, The Celestine, Fuenteovejuna, Stanzas about the Death of his Father or crea-tions by the writer Garcilaso de la Vega. Likewise, by using the values emerging from the texts and, therefore, by showing their timelessness, these workshops are to have an impact on individuals formation and on trying to achieve an inclusive school and thence, society. .S
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El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria)
'Universitat Politecnica de Valencia', 2016Co-Authors: Cantero Sandoval Almudena, Pena Presas MontseAbstract:[EN] Access to classic texts by students is still a challenge in Spanish Language and Literature lessons during Compulsory Secondary Education. At the same time, literature for children and young adults is getting more and more present in this educational stage. The present didactic proposal intends to exemplify how —by means of workshops to be developed throughout an academic year— a picture book can motivate and make the reading of different Spanish canonical works more accessible. Some examples of that would be: The Life of Lazarillo de Tormes, The Celestine, Fuenteovejuna, Stanzas about the Death of his Father or crea-tions by the writer Garcilaso de la Vega. Likewise, by using the values emerging from the texts and, therefore, by showing their timelessness, these workshops are to have an impact on individuals formation and on trying to achieve an inclusive school and thence, society.[EN] El acceso a los textos clásicos por parte del alumnado sigue siendo un reto en las clases de lengua y literatura de la Educación Secundaria Obligatoria. Al mismo tiempo, es cada vez mayor la presencia que la literatura infantojuvenil adquiere en esta etapa educativa. Esta propuesta didáctica quiere ejemplificar como, a través de la formulación de talleres, un álbum ilustrado puede motivar y hacer más accesible la lectura de diferentes obras canónicas como son el Lazarillo de Tormes, La Celestina, Fuenteovejuna, Coplas por la muerte de su padre o las creaciones de Garcilaso de la Vega. Igualmente, utilizando los valores que emanan los diferentes textos y, por lo tanto, mostrando su atemporalidad, estos talleres incidirán en la formación de individuos para lograr una escuela y, por tanto, una sociedad inclusiva.Cantero Sandoval, A.; Pena Presas, M. (2016). El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria). Lenguaje y Textos. (43):89-96. doi:10.4995/lyt.2016.5939.SWORD89964
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El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria)
'Universitat Politecnica de Valencia', 2016Co-Authors: Cantero Sandoval Almudena, Pena Presas MontseAbstract:[EN] Access to classic texts by students is still a challenge in Spanish Language and Literature lessons during Compulsory Secondary Education. At the same time, literature for children and young adults is getting more and more present in this educational stage. The present didactic proposal intends to exemplify how —by means of workshops to be developed throughout an academic year— a picture book can motivate and make the reading of different Spanish canonical works more accessible. Some examples of that would be: The Life of Lazarillo de Tormes, The Celestine, Fuenteovejuna, Stanzas about the Death of his Father or crea-tions by the writer Garcilaso de la Vega. Likewise, by using the values emerging from the texts and, therefore, by showing their timelessness, these workshops are to have an impact on individuals formation and on trying to achieve an inclusive school and thence, society.[EN] El acceso a los textos clásicos por parte del alumnado sigue siendo un reto en las clases de lengua y literatura de la Educación Secundaria Obligatoria. Al mismo tiempo, es cada vez mayor la presencia que la literatura infantojuvenil adquiere en esta etapa educativa. Esta propuesta didáctica quiere ejemplificar como, a través de la formulación de talleres, un álbum ilustrado puede motivar y hacer más accesible la lectura de diferentes obras canónicas como son el Lazarillo de Tormes, La Celestina, Fuenteovejuna, Coplas por la muerte de su padre o las creaciones de Garcilaso de la Vega. Igualmente, utilizando los valores que emanan los diferentes textos y, por lo tanto, mostrando su atemporalidad, estos talleres incidirán en la formación de individuos para lograr una escuela y, por tanto, una sociedad inclusiva.Cantero Sandoval, A.; Pena Presas, M. (2016). El álbum ilustrado como puente entre la literatura canónica y la educación inclusiva (una propuesta didáctica para educación secundaria). Lenguaje y Textos. (43):89-96. doi:10.4995/lyt.2016.5939.SWORD899643ANÓNIMO. (2006). Lazarillo de Tormes. Madrid: Alfaguara.Blanco, R. (1999). Hacia una escuela para todos y con todos. Boletín del Proyecto Principal de Educación para América Latina y el Caribe, 48, 55-72.De Rojas, F. (2006). La Celestina. Madrid: Alfaguara.García Padrino, J. (1992). Literatura infantil y educación. En: CERRILLO, P. y GARCÍA PADRINO, J .(Coords.). Literatura infantil y ense-anza de la literatura, pp.13-25. Cuenca: Ediciones de la Universidad de Castilla-La Mancha.Green, M. (2005). Liberar la imaginación. Ensayos sobre educación, arte y cambio social. Barcelona: Graó.Manrique, J. (1993). Coplas a la muerte de su padre. Madrid: Castalia.Núñez Delgado, M. P. (2001). Comunicación y expresión oral. Hablar, escuchar y leer en Secundaria. Madrid: Narcea.Silva-Díaz, C. (2003). "¡Qué libros más raros! Construcción y evaluación de un instrumento para describir las variaciones metaficcionales en el álbum. Anuario de Investigación en Literatura Infantil y Juvenil, 1, 167-189
Catherine Lerouge - One of the best experts on this subject based on the ideXlab platform.
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constraining porewater chemistry in a 250 m thick argillaceous rock sequence
Chemical Geology, 2016Co-Authors: Paul Wersin, Catherine Lerouge, Martin Mazurek, Urs Mader, Thomas Gimmi, Daniel Rufer, Daniel TraberAbstract:The geochemistry of an argillaceous rock sequence from a deep borehole in NE-Switzerland was investigated. The focus was to constrain the porewater chemistry in low permeability Jurassic rocks comprising the Liassic, the Opalinus Clay formation, the „Brown Dogger‟ unit and the Effingen Member (Malm). A multi-method approach including mineralogical analysis, aqueous and Ni-ethylenediamine extraction, squeezing tests and pCO2 measurements as well as geochemical modelling was applied for this purpose. A consistent dataset was obtained with regard to the main solutes in the porewaters. A fairly constant anionaccessible porosity of 50% of the total porosity was deduced for all analysed samples which displayed variable clay-mineral contents. Sulphate concentrations were shown to be constrained by a sulphate-bearing phase, presumably by celestite or a Sr-Ba sulphate. Application of a simple equilibrium model, including cation exchange reactions, calcite and celestite equilibrium showed good agreement with squeezing data, indicating the suitability of the modelling approach to simulate porewater chemistry in the studied argillaceous rocks. The modelling highlighted the importance of correct determination of the exchangeable cation population. The analysis corroborates that squeezing of the studied rocks is a viable and efficient way to sample porewater.
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mineralogical and isotopic record of biotic and abiotic diagenesis of the callovian oxfordian clayey formation of bure france
Geochimica et Cosmochimica Acta, 2011Co-Authors: Catherine Lerouge, Eric C. Gaucher, Christophe Tournassat, Catherine Guerrot, Sylvain Grangeon, Pierre Agrinier, David Widory, Christine Flehoc, Guillaume Wille, Claire RambozAbstract:Abstract The Callovian–Oxfordian (COx) clayey unit is being studied in the Eastern part of the Paris Basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal. The present study combines new mineralogical and isotopic data to describe the sedimentary history of the COx unit. Petrologic study provided evidence of the following diagenetic mineral sequence: (1) framboidal pyrite and micritic calcite, (2) iron-rich euhedral carbonates (ankerite, sideroplesite) and glauconite (3) limpid calcite and dolomite and celestite infilling residual porosity in bioclasts and cracks, (4) chalcedony, (5) quartz/calcite. Pyrite in bioturbations shows a wide range of δ34S (−38‰ to +34.5‰), providing evidence of bacterial sulphate reduction processes in changing sedimentation conditions. The most negative values (−38‰ to −22‰), measured in the lower part of the COx unit indicate precipitation of pyrite in a marine environment with a continuous sulphate supply. The most positive pyrite δ34S values (−14‰ up to +34.5‰) in the upper part of the COx unit indicate pyrite precipitation in a closed system. Celestite δ34S values reflect the last evolutionary stage of the system when bacterial activity ended; however its deposition cannot be possible without sulphate supply due to carbonate bioclast dissolution. The 87Sr/86Sr ratio of celestite (0.706872–0.707040) is consistent with deposition from Jurassic marine-derived waters. Carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates. Siderite, only present in the maximum clay zone, has chemical composition and δ18O consistent with a marine environment. Its δ13C is however lower than those of marine carbonates, suggesting a contribution of 13C-depleted carbon from degradation of organic matter. δ18O values of diagenetic chalcedony range between +27‰ and +31‰, suggesting precipitation from marine-derived pore waters. Late calcite crosscutting a vein filled with chalcedony and celestite, and late euhedral quartz in a limestone from the top of the formation have lower δ18O values (∼+19‰), suggesting that they precipitated from meteoric fluids, isotopically close to present-day pore waters of the formation. Finally, the study illustrates the transition from very active, biotic diagenesis to abiotic diagenesis. This transition appears to be driven by compaction of the sediment, which inhibited movement of bacterial cells by reduction of porosity and pore sizes, rather than a lack of inorganic carbon or sulphates.
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Mineralogical and isotopic record of biotic and abiotic diagenesis of the Callovian-Oxfordian clayey formation of Bure (France)
Geochimica et Cosmochimica Acta, 2011Co-Authors: Catherine Lerouge, Eric C. Gaucher, Christophe Tournassat, Catherine Guerrot, Sylvain Grangeon, Pierre Agrinier, David Widory, Christine Flehoc, Guillaume Wille, Claire RambozAbstract:The Callovian-Oxfordian (COx) clayey unit is being studied in the Eastern part of the Paris Basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal. The present study combines new mineralogical and isotopic data to describe the sedimentary history of the COx unit. Petrologic study provided evidence of the following diagenetic mineral sequence: (1) framboidal pyrite and micritic calcite, (2) iron-rich euhedral carbonates (ankerite, sideroplesite) and glauconite (3) limpid calcite and dolomite and celestite infilling residual porosity in bioclasts and cracks, (4) chalcedony, (5) quartz/calcite. Pyrite in bioturbations shows a wide range of δ34S (−38‰ to +34.5‰), providing evidence of bacterial sulphate reduction processes in changing sedimentation conditions. The most negative values (−38‰ to −22‰), measured in the lower part of the COx unit indicate precipitation of pyrite in a marine environment with a continuous sulphate supply. The most positive pyrite δ34S values (−14‰ up to +34.5‰) in the upper part of the COx unit indicate pyrite precipitation in a closed system. Celestite δ34S values reflect the last evolutionary stage of the system when bacterial activity ended; however its deposition cannot be possible without sulphate supply due to carbonate bioclast dissolution. The 87Sr/86Sr ratio of celestite (0.706872-0.707040) is consistent with deposition from Jurassic marine-derived waters. Carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates. Siderite, only present in the maximum clay zone, has chemical composition and δ18O consistent with a marine environment. Its δ13C is however lower than those of marine carbonates, suggesting a contribution of 13C-depleted carbon from degradation of organic matter. δ18O values of diagenetic chalcedony range between +27‰ and +31‰, suggesting precipitation from marine-derived pore waters. Late calcite crosscutting a vein filled with chalcedony and celestite, and late euhedral quartz in a limestone from the top of the formation have lower δ18O values (not, vert, similar+19‰), suggesting that they precipitated from meteoric fluids, isotopically close to present-day pore waters of the formation. Finally, the study illustrates the transition from very active, biotic diagenesis to abiotic diagenesis. This transition appears to be driven by compaction of the sediment, which inhibited movement of bacterial cells by reduction of porosity and pore sizes, rather than a lack of inorganic carbon or sulphates.
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Strontium distribution and origins in a natural clayey formation (Callovian-Oxfordian, Paris Basin, France): A new sequential extraction procedure
Geochimica et Cosmochimica Acta, 2010Co-Authors: Catherine Lerouge, Eric C. Gaucher, Christophe Tournassat, Philippe Négrel, Catherine Crouzet, Catherine Guerrot, Anne Gautier, Pascale Michel, Agnès Vinsot, Stéphane BuschaertAbstract:Strontium is a good monitor of geochemical processes in natural clayey formations. In the Callovian-Oxfordian formation of Bure in France, strontium is sorbed on clay minerals and carried by carbonates, detrital minerals and accessory celestite. In order to determine the strontium distribution among these different phases, four-step sequential extractions (I. cobalt hexamine trichloride, 2. acetic acid, 3. EDTA and 4. tri-acid) were performed on samples from different levels of the clayey formation. The leachates were also analyzed for strontium isotopes, in order to determine the strontium origins. This sequential procedure is well suited to determining strontium distribution in claystones, although it is less efficient in clay-rich limestones and in celestite-rich samples. The carbonates (38-47% of the total strontium) show Sr-87/Sr-86 ratios (0.7070-0.7071) that have recorded the isotopic composition of the Callovian-Oxfordian seawater. Diagenetic carbonates (dolomite, ankerite and siderite) have almost not incorporated any strontium, which has been trapped by celestite during the late diagenesis. The major part of the celestite shows Sr-87/Sr-86 ratios (0.7069-0.7070) quite close to the primary carbonates. However, a second generation of celestite (0.7074) shows a slight Sr-87-enrichment and is isotopically in equilibrium with the exchangeable strontium (27-48% of the total strontium with a mean Sr-87/Sr-86 value of 0.70745) and the present-day porewater (0.7074). This very low Sr-87-enrichment could be explained by the partial destabilisation of detrital minerals (feldspars, micas, clays) which exhibit 87Sr/86Sr ratios consistent with their pristine Hercynian origin (0.7229-0.7350). Diffusion of strontium from the subjacent Dogger aquifers (0.7076-0.7082) could also be invoked to explain the slight 87Sr-enrichment.
Vadim S Kamenetsky - One of the best experts on this subject based on the ideXlab platform.
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mantle oddities a sulphate fluid preserved in a marid xenolith from the bultfontein kimberlite kimberley south africa
Earth and Planetary Science Letters, 2013Co-Authors: Andrea Giuliani, David Phillips, Marco L Fiorentini, Mark A Kendrick, Roland Maas, Boswell A Wing, Jonathan Woodhead, Thi Hao Bui, Vadim S KamenetskyAbstract:Article history: Sulphur in the lithospheric mantle is concentrated in sulphide minerals, with limited evidence for the occurrence of sulphate phases. Here we describe an unusual assemblage of Celestine (SrSO4), clinopyroxene and minor phlogopite, pectolite, sphene, apatite, barite (BaSO4) and Ca-Sr carbonates in a MARID mantle xenolith sampled by the Bultfontein kimberlite (Kimberley, South Africa). This assemblage occurs in veins that pervasively traverse the xenolith, indicating that Celestine and the other vein minerals crystallised from a fluid. In the MARID host rock, K-richterite is resorbed where in contact with Celestine and is overgrown by clinopyroxene. Celestine hosts the other metasomatic vein phases, but also occurs as inclusions in euhedral clinopyroxene, suggesting co-precipitation of these minerals. Celestine was partly replaced by serpentine during alteration by hydrous fluids after kimberlite emplacement in the upper crust. Celestine has relatively radiogenic Sr isotopes ( 87
Claire Ramboz - One of the best experts on this subject based on the ideXlab platform.
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mineralogical and isotopic record of biotic and abiotic diagenesis of the callovian oxfordian clayey formation of bure france
Geochimica et Cosmochimica Acta, 2011Co-Authors: Catherine Lerouge, Eric C. Gaucher, Christophe Tournassat, Catherine Guerrot, Sylvain Grangeon, Pierre Agrinier, David Widory, Christine Flehoc, Guillaume Wille, Claire RambozAbstract:Abstract The Callovian–Oxfordian (COx) clayey unit is being studied in the Eastern part of the Paris Basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal. The present study combines new mineralogical and isotopic data to describe the sedimentary history of the COx unit. Petrologic study provided evidence of the following diagenetic mineral sequence: (1) framboidal pyrite and micritic calcite, (2) iron-rich euhedral carbonates (ankerite, sideroplesite) and glauconite (3) limpid calcite and dolomite and celestite infilling residual porosity in bioclasts and cracks, (4) chalcedony, (5) quartz/calcite. Pyrite in bioturbations shows a wide range of δ34S (−38‰ to +34.5‰), providing evidence of bacterial sulphate reduction processes in changing sedimentation conditions. The most negative values (−38‰ to −22‰), measured in the lower part of the COx unit indicate precipitation of pyrite in a marine environment with a continuous sulphate supply. The most positive pyrite δ34S values (−14‰ up to +34.5‰) in the upper part of the COx unit indicate pyrite precipitation in a closed system. Celestite δ34S values reflect the last evolutionary stage of the system when bacterial activity ended; however its deposition cannot be possible without sulphate supply due to carbonate bioclast dissolution. The 87Sr/86Sr ratio of celestite (0.706872–0.707040) is consistent with deposition from Jurassic marine-derived waters. Carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates. Siderite, only present in the maximum clay zone, has chemical composition and δ18O consistent with a marine environment. Its δ13C is however lower than those of marine carbonates, suggesting a contribution of 13C-depleted carbon from degradation of organic matter. δ18O values of diagenetic chalcedony range between +27‰ and +31‰, suggesting precipitation from marine-derived pore waters. Late calcite crosscutting a vein filled with chalcedony and celestite, and late euhedral quartz in a limestone from the top of the formation have lower δ18O values (∼+19‰), suggesting that they precipitated from meteoric fluids, isotopically close to present-day pore waters of the formation. Finally, the study illustrates the transition from very active, biotic diagenesis to abiotic diagenesis. This transition appears to be driven by compaction of the sediment, which inhibited movement of bacterial cells by reduction of porosity and pore sizes, rather than a lack of inorganic carbon or sulphates.
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Mineralogical and isotopic record of biotic and abiotic diagenesis of the Callovian-Oxfordian clayey formation of Bure (France)
Geochimica et Cosmochimica Acta, 2011Co-Authors: Catherine Lerouge, Eric C. Gaucher, Christophe Tournassat, Catherine Guerrot, Sylvain Grangeon, Pierre Agrinier, David Widory, Christine Flehoc, Guillaume Wille, Claire RambozAbstract:The Callovian-Oxfordian (COx) clayey unit is being studied in the Eastern part of the Paris Basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal. The present study combines new mineralogical and isotopic data to describe the sedimentary history of the COx unit. Petrologic study provided evidence of the following diagenetic mineral sequence: (1) framboidal pyrite and micritic calcite, (2) iron-rich euhedral carbonates (ankerite, sideroplesite) and glauconite (3) limpid calcite and dolomite and celestite infilling residual porosity in bioclasts and cracks, (4) chalcedony, (5) quartz/calcite. Pyrite in bioturbations shows a wide range of δ34S (−38‰ to +34.5‰), providing evidence of bacterial sulphate reduction processes in changing sedimentation conditions. The most negative values (−38‰ to −22‰), measured in the lower part of the COx unit indicate precipitation of pyrite in a marine environment with a continuous sulphate supply. The most positive pyrite δ34S values (−14‰ up to +34.5‰) in the upper part of the COx unit indicate pyrite precipitation in a closed system. Celestite δ34S values reflect the last evolutionary stage of the system when bacterial activity ended; however its deposition cannot be possible without sulphate supply due to carbonate bioclast dissolution. The 87Sr/86Sr ratio of celestite (0.706872-0.707040) is consistent with deposition from Jurassic marine-derived waters. Carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates. Siderite, only present in the maximum clay zone, has chemical composition and δ18O consistent with a marine environment. Its δ13C is however lower than those of marine carbonates, suggesting a contribution of 13C-depleted carbon from degradation of organic matter. δ18O values of diagenetic chalcedony range between +27‰ and +31‰, suggesting precipitation from marine-derived pore waters. Late calcite crosscutting a vein filled with chalcedony and celestite, and late euhedral quartz in a limestone from the top of the formation have lower δ18O values (not, vert, similar+19‰), suggesting that they precipitated from meteoric fluids, isotopically close to present-day pore waters of the formation. Finally, the study illustrates the transition from very active, biotic diagenesis to abiotic diagenesis. This transition appears to be driven by compaction of the sediment, which inhibited movement of bacterial cells by reduction of porosity and pore sizes, rather than a lack of inorganic carbon or sulphates.