La extensión Triásica en el substrato de la Cuenca del Maestrat, y evidencias de tectónica salina en las evaporitas en facies Muschelkalk medio (Cadena Ibérica Oriental)

Abstract

The Maestrat Basin was one of the most subsident basins of the Mesozoic Iberian Rift System. During the first stage of extensional activity (Late Permian-Late Triassic) a high angle normal fault system developed, which fragmented the Variscan basement into a system of horsts, grabens and half-grabens. Those faults were active during the deposition of the Buntsandstein facies and lasted until the lower part of the Middle Muschelkalk facies was deposited, filling the system of horsts and grabens and generating depositional thickness variations. The fault system was overstepped by the upper part of the Middle Muschelkalk, indicating a decrease in the extensional activity that lasted until the carbonates of the Upper Muschelkalk facies were deposited, as they present nearly constant thickness. During the Keuper facies deposition, the extensional activity of some normal faults in the acoustic basement resumed, triggering the Middle Muschelkalk salt flow, which developed salt anticlines and welds, increasing the depositional thickness variations of this facies. The age of the salt flow is deduced from the Keuper facies reflectors lapping on the folded Upper Muschelkalk above the salt accumulations. Growth-strata above some Upper Muschelkalk forced folds are also recognized, developed above some reactivated normal faults in the basement.