Efectos del contenido de CaCO3 inicial en las propiedades magnéticas de sedimentos calcinados. Resultados preliminares

Abstract

In this work, the influence of the initial CaCO3, on the magnetic properties of calcinedsediments, is evaluated. This contribution ispart of a wider study, about magnetic mineralogydeveloped from sediment calcinationof different compositions at diverse temperatures.High temperatures in sediments causechemical-mineralogical transformations thatdepend, mainly, upon their original composition.Some examples of this are burned soils,pyrometamorphic and diagenetic processes ormeteorite impact zones. Transformations couldbe similar, even analogous, to some industrialprocesses, like bricks, ceramics and cementsmanufacturing. The determination of magneticparameters (magnetic susceptibility and isothermalremanent magnetization) and majorchemical elements was made in sediments withcontrasting amounts of CaCO3. The thermalprocess was performed at 1000 ºC in air atmosphere.Before heating, the behavior ofmagnetic composition indicates a significanthomogeneity as regarding the magnetic parameters.These behaviors are undoubtedly related tothe ferrimagnetic series of titanomagnetites andprobably to the maghemite signal as well. Incontrast, calcined samples presented magneticrecords that vary noteworthy in relation to theCaO (or initial CaCO3) content. After heating,the samples with lower CaO (< 4 %) concentrationsshowed a magnetic signal related toantiferromagnetic minerals, like hematite. Thesamples with higher CaO contents (8–29 %)showed a magnetic signal related to ferrimagneticminerals. Besides, all calcined samplesshowed a high contribution of nanoparticleswith superparamagnetic properties.