Deformed rocks can provide vital information when studying the tectonic and metamorphic evolution of a mineral deposit. Microstructures and their overprinting relationships identified in these rocks can be an important source when trying to reconstruct the sequence of deformational events that has affected a region.

The Alconchel Cu-Au project in southwestern Spain has been subject to a microscopical study in order to investigate how the deposit has been affected by tectonic deformation during its geological evolution. Three drill holes from different location in the project area were logged and examined, 27 samples were taken and prepared into polished thin-sections. The focus for the microscopical study has been to try to identify relevant microstructures, alterations and minerals of interest and by their cross-cutting relationships try to interpret and determine a relative sequence of deformation.

The study identified at least three main types of deformation which has been interpreted to represent three separate deformation events. These events have been abbreviated to D₁, D₂ and D₃ with D₁ representing the earliest deformation.

The D₁ event is interpreted to represent compaction force and forming a S₀/S₁ fabric. Two possible theories for the formation of these S1 features are discussed. The second event (D₂) has caused folding of the previous structures and the formation of an axial plane parallel crenulation cleavage. The occurrence of different generations of magnetite and hematite growing with or over some of the deformation features argues for a prograde type of metamorphism with peak metamorphism conditions post-dating peak strain conditions. A later brittle event, D₃, has brittlely faulted these older features. Faults and micro faults from this D₃ event can be seen both in the drill core but also on a microscopical level.

Shear zone activity has been suggested to be an important source for the transportation and deposition of interesting mineralizations. Two shear zone events related the later stages of D1 and D2 respectively, are believed to have been identified.