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Abstract

RESUMENUn estudio mediante MEB de silcretas miocenas opalinas formadas por silicificación de playas en un ambiente de «playa-lake» pone de manifiesto la existencia de una nueva microestructura de ópalo CT. Esta microestructura denominada en general fibrosa, se manifiesta por la presencia de multitud de fibras, filamentos o varillas formadas por la alineación de microesferas o microhemisferas que presentan un diámetro entre 0, l Y 0,2 1.1. Las fibras, filamentos o varillas tienen formas variables: rectas, curvadas, onduladas y «en horquilla», y presentan longitudes de hasta 10 11, aunque podrían existir longitudes mayores. La disposición organizada de las microesferas en filamentos o fibras, constituyendo la masa general del ópalo, y su parecido con microestructuras opalinas que han sido formadas por influencia bacteriana, hacen considerar esta hipótesis, aunque no se puede descartar totalmente un origen inorgánico por silicificación de sepiolita. Palabras clave: Microesferas, fihas, Opa/o CT, bacterias, si/cretas.ABSTRACT Electron microscope observations of opaline silcretes found in the playa of a miocene shallow lake reveal new opal CT microstructures. These microstructures are made up of fibres, filaments or rods, which are formed, in tum by coalesced microspheres or microhemispheres (0,1-0,2 11 diameter). They are up to 10 11 in length although larger ones could exist. They are straight, bent, wavy or even hairpin shaped. These microstructures comprise part of the opaline mass of the silcretes and are very similar to both neogenic opaline structures which are formed by bacterial intluence and to silicified biofilms. Therefore microbial mediation could exist in the genesis of this opal CT, although a possible inorganic origin by silicification of sepiolite is also considered.

Adsorption of CO2 by alkali metals and weak alkali rare earth metals supported on aluminum pillared diatomite

“…[21][22][23][24][25] Diatomite has fine, loose, light weight, porous, water absorption and strong permeability. Its loose density is 0.4g/cm 3 , [26][27][28] Mohs hardness is 1-1.5 (diatom skeleton particle is 4.5-5mm), porosity is 80-90%. The elemental composition of diatomite is as follows: 82.21wt% SiO 2 , 4.81wt% Al 2 O 3 , 1.82wt% CaO, 1.61wt% MgO, 1.33wt% Fe 2 O 3 , 0.48wt% K 2 O 0.14wt% Na 2 O.…”