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Gypsum deposits are the currently exploited sulphate rocks with industrial purposes. In addition to the expensive drilling projects, geophysical techniques can be considered to estimate the economical potential of these deposits. An electrical resistivity tomography survey has been carried out in the Pira gypsum formation (SE of the Catalan margin of the Tertiary Ebro Basin, Spain). Additionally, a continuous coring drill was performed in order to support the study. Electrical imaging has been successfully applied to identify the gypsum deposits interlayered in lutite units. Nevertheless, the gypsum-lutite boundaries are diffuse and uncertain in the tomographic lines. Comparison of the cores of the borehole and the electrical response shows a meaningful correlation between electrical resistivity and purity of gypsum. The electrical resistivity tomography profiles display a rather wide range of electrical resistivity value (from 20-1000 Ωm) for the investigated gypsum facies. The highest values are attributed to sulphate layers with >90% of gypsum mineral. Lutite units display higher values than expected due to the presence of evaporite minerals within them (>10 Ωm). Additionally, induced polarization measures have been performed in order to study the chargeability of gypsum deposits. It has been evidenced that impure gypsum rocks (with important presence of lutites within) are slightly chargeable. This property has allowed distinguishing between lutite levels and clay-rich gypsum rocks. Electrical resistivity tomography lines are useful in the prospection of gypsum deposits. However, electrical imaging prospection should be supported by an accurate petrological study of the deposits, in order to properly interpret the resistivity profiles.

La glauberita es un sulfato sódico que se explota con fines industriales. En el año 2002 en los depósitos evaporíticos miocenos de la formación Yesos y Anhidritas de Zaragoza se encontró glauberita en profundidad en una campaña de sondeos. Mediante la técnica geofísica de la tomografía eléctrica se han llevado a cabo una serie de perfiles de resistividad eléctrica del terreno. Los datos obtenidos en el estudio se han comparado con la información previa de los sondeos y se ha podido constatar que partiendo de estos, es posible obtener información de los depósitos y observar como evolucionan lateralmente. Debido a la importante presencia de encajante no se ha podido definir el rango de valores geoeléctricos de resistividad propios de la glauberita pura pero si se han reconocido estructuras kársticas y deposicionales

New Pb isotopic analyses have been obtained on twenty samples of galena from the Azuaga area. In spite of the overall homogeneity, the results for samples to the North of the Azuaga Fault are perceptible different from those to the South. The observed difference is tentatively related to the nature of the host rocks on both sides of the fault. The new data are consistent with previous values of Pb isotopic composition for galenas from the same region. Yet, these results reveal some incongruity in previous models as regards the origin of Pb in the Azuaga area. We favour a model involving the participation of lower crustal or equivalent rock units rather than a mantle-related source for the Pb

New Pb isotopic analyses have been obtained on twenty samples of galena from the Azuaga area. In spite of the overall homogeneity, the results for samples to the North of the Azuaga Fault are perceptible different from those to the South. The observed difference is tentatively related to the nature of the host rocks on both sides of the fault. The new data are consistent with previous values of Pb isotopic composition for galenas from the same region. Yet, these results reveal some incongruity in previous models as regards the origin of Pb in the Azuaga area. We favour a model involving the participation of lower crustal or equivalent rock units rather than a mantle-related source for the Pb