Publication: Silicificación de comunidades microbianas en complejos vulcanosedimentarios: comparación entre una caldera volcánica neoproterozoica del Anti-Atlas (Marruecos) y la dorsal atlántica (Islandia)
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2018-09-26
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Universidad Complutense de Madrid
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Abstract
Esta tesis doctoral presenta un estudio comparativo sobre la conservación de fábricas ytexturas microbianas en dos complejos vulcanosedimentarios: (1) la caldera de Oued Dar’a,en el en el Ediacárico terminal del Supergrupo de Ouarzazate (Anti-Atlas oriental,Marruecos), que representa la fase terminal de la Orogenia Pan-Africana, y (2) el campogeotermal de Seltún en la península de Reyjkanes (Islandia), situada en la parte septentrionalde la dorsal atlántica actual. El objetivo incluye la caracterización de los mediossedimentarios de calderas volcánicas, en los que se han registrado varios procesos debiomineralización, principalmente relacionados con la silicificación de biofilms, tapices yestromatolitos microbianos, a partir del estudio de sus facies sedimentarias, fábricas ytexturas microbianas y el registro de procesos diagenéticos, en su aspecto petrológico,mineralógico y geoquímico. Para ello se ha realizado un estudio analítico y microscópico, aescala centimétrica, milimétrica y nanométrica, de los restos microbianos a partir de losmicroscopios petrográfico y electrónico de barrido (MEB), acoplados a espectrómetros deenergía dispersiva de rayos X (Energy Dispersive X-Ray Spectrometry, EDS),catodoluminiscencia (CL) y difracción de rayos X (DRX)...
This PhD thesis documents a study that aims to make a comparison about the preservationof microbial fabrics and textures in two volcanosedimentary complexes: (i) the Oued Dar’acaldera exposed in the uppermost Ediacaran Ouarzazate Supergroup (eastern Anti-Atlas,Morocco), which represents the end of the Pan-African Orogeny, and (ii) the Seltungeothermal area of the Reyjkanes Peninsula (Iceland), located in the present-day exposuresof the northern Mid-Atlantic Ridge. The aim of this work is the characterization of thesedimentary environments recorded in both volcanic calderas, which exhibit a wide varietyof biomineralization processes, mainly related to silicification of biofilms, mats andstromatolites. The study is based on the analysis of sedimentary facies, microbial fabricsand textures and the record of diagenetic processes, focused on their petrologic,mineralogical and geochemical features. The latter include a dataset of analytical andmicroscopic results, at the cm, mm and nm scale yielded by the petrographic and ScanningElectron Microscopy (SEM) microscopies, Energy-Dispersive X-Ray Spectroscopy (EDS),cathodoluminescence (CL) and X-Ray Diffraction (XRD) analyses...
This PhD thesis documents a study that aims to make a comparison about the preservationof microbial fabrics and textures in two volcanosedimentary complexes: (i) the Oued Dar’acaldera exposed in the uppermost Ediacaran Ouarzazate Supergroup (eastern Anti-Atlas,Morocco), which represents the end of the Pan-African Orogeny, and (ii) the Seltungeothermal area of the Reyjkanes Peninsula (Iceland), located in the present-day exposuresof the northern Mid-Atlantic Ridge. The aim of this work is the characterization of thesedimentary environments recorded in both volcanic calderas, which exhibit a wide varietyof biomineralization processes, mainly related to silicification of biofilms, mats andstromatolites. The study is based on the analysis of sedimentary facies, microbial fabricsand textures and the record of diagenetic processes, focused on their petrologic,mineralogical and geochemical features. The latter include a dataset of analytical andmicroscopic results, at the cm, mm and nm scale yielded by the petrographic and ScanningElectron Microscopy (SEM) microscopies, Energy-Dispersive X-Ray Spectroscopy (EDS),cathodoluminescence (CL) and X-Ray Diffraction (XRD) analyses...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída el 30-11-2017