Modelling of the Cala area (Ossa-Morena Zone)

Abstract

The Cala project area is a region ca. 400 km 2 in size that comprises several mines and prospects hosted by Palaeozoic rocks. The Cala area is located in the southern segment of the Iberian Massif that forms the pre-Mesozoic basement in most of the Iberian Peninsula and constitutes the westernmost extent of the European Variscan orogeny. More precisely, it is situated in the southwestern limb of the Monesterio Antiform, within the Ossa-Morena Zone (OMZ), which exposes a complex geological evolution. The current structure of the OMZ is mainly due to the Variscan orogeny. This study is focused on Variscan plutons that were emplaced into Late Proterozoic and Paleozoic sediments. Igneous and metamorphic activity of the Variscan Orogeny led to the formation of various types of mineralization. Two of these are studied in this paper: the iron oxide replacement and skarn in the Cala mine and the Ni-(Cu-PGE) deposit in the Aguablanca mafic to ultramafic intrusion. The aim of this work is to build three 3D geological models: one at regional scale (Cala regional model) and two at local scale (Cala mine and Aguablanca deposit). To achieve this we have improved the previous geological mapping and carried out two regional gravity surveys and one detailed survey in the neighborhood of Cala mine. Moreover, in order to study the Aguablanca deposit the geological information supplied by Lundin Mining was very useful. The use of geophysical data provide a tool to check the final models. Fully honoring the geological data and starting cross-sections, best processing practices, model properties based on petrophysical data,