Estudio al M. E.B.de las texturas superficiales de los granos de cuarzo y su aplicación a la interpretación de medios actuales y subactuales

Abstract

A spectrum of representative quartz grains of different sedimentary environments (beach, aeolian, fluvial), from recent, Quaternary and Pliocene ages has been examined under a Scanning Electron Microscope. The environment of deposition of the fossil sequences was previously established by other sedimentological techniques, The purpose of the present investigation is to establish the degree of validity of "Surface textural Analysis of Quartz" to several different sedimentary environmeats distinguished on the basis of their surface textures. The Plio-Quaternary "Arenas Rojas" Formation from the Vejer-Medina area, which is of controversial origin has also been studied. The purpose here is to contribute to a better understanding of its sedimentary environment. The following analysis has been made as a complement to our S.E.M. study: The grain-size distribution of all examined samples was studied with binocular and petrographic microscopes. A diagnostic surface feature glossary is described in this paper for the purpose of comparing terminologies. This information is necessary because of the confusion that exists in literature. Within the littoral beach-aeolian environment, recent "Valdelagrana" and in the fossil "El Aculadero" (both in the Bahía de Cádiz), satisfactory results have been obtained in relation to other sedimentological data; other superimposed features related to diagenetic and edaphic processes are also be noted. The sequence of different environments has been studied within the "Arenas Rojas" Formation. Our data do not contradict the prevailing literature, but we used quantitative combined feature analysis on a large number of samples to study minor deviations from published analyses.