Estudio geológico y minero de los depósitos de alabastro en el entorno de Velilla de Ebro y Azaila (Aragon, NE de España)

Abstract

This work studies the main alabaster «transparent» variety) deposits commercialized in Spain. These deposits are located in the province of Zaragoza. at its border with Teme!. Stratigraphically. the quarried area is located at the SE border of the Tertiary Ebro basin (UTS: T 4 • Upper Oligocene). ando within it, at the Calanda-Valderrobres-Escatron sector. Mining appraisals carried out sanctioned the presence of three productive levels of alabaster. A mineralization guide sequence was found for the upper level (height 250 m). The mineral body texture is nodular. arranged in layers of wide horizontal continuity (kilometers) and average thickness 0,4 to 1 m. Petrographic studies of the alabaster mineral bodies have shown three types of microstmctures. Considering the stratigraphic column of the area we found from top to bottom of each iayer the following microstmctures: a) microcrystalline aggregates; b) porphyroblastic microtexture with non uniform extinction of crystaline components; and c) granoblastic microtextures. The sedimentary environment of the deposits was shallow continental type (playa-Iake), characterized by mud-flats and distal fluvial-flats.