Active fault control on Plio-Quaternary gypsum veins systems (the Galera Fault, S Spain)

Abstract

Gypsum veins were formed during the Pliocene and Pleistocene within the damage zone of the active,left-lateral Galera Fault (central Betic Cordillera, S Spain). Structural analysis reveals that vein distributionand geometry are controlled by fault activity. Veins grew in a band around the fault, which width varies according to the complexity of the fault array. Vein size increases near main fault strands. There is a closerelationship between vein orientation and the arrangement, kinematics, and interactions of the faultsconforming the fault zone. Veins are aligned with fractures accommodating transtensional deformationwithin the strain field of the fault. However, vein orientation is highly sensitive to small strain fieldvariations due to the presence of local structures resulted from fault displacement. Rotation of some vein sets indicates that vein growth initiated shortly after the deposition of the Plio-Pleistocene host rocks, simultaneously to fault activity. Early vein sets formed perpendicular to bedding under shallow burial conditions, conditioning the growth of future veins with different orientations.