Structuration and sedimentary response to continental Mesozoicrifting in northeastern Iberia

Abstract

Iberia and its oceanic margins provide evidence of a large rift system developed in three phases: i) latePermian–Middle Triassic, ii) Late Jurassic, and iii) Barremian–early Albian. These rifting events were coevalwith the opening of the Alpine Tethys, the North-Atlantic, and the Bay of Biscay domains, respectiely. Thethree Mesozoic rifting phases controlled the development of Iberian intraplate rift basins, including theMaestrat and Garraf basins, which are the focus of this study. Each of these rifting stages was followed bya period of decelerated or post-rift thermal subsidence. The first post-rift phase, spanning the Late Triassicto the early Late Jurassic, was interrupted by a short-lived interval of rapid syn-rift subsidence during theHettangian, here referred to as the Hettangian event. Rifting cycles 2 and 3 are separated by the Neocomianevent, which corresponds to an interval of decelerated subsidence. The earliest rifting phase is associated withan early inception of saline tectonics in the Maestrat Basin, and was accompanied by magmatism and tookplace in an arid climate setting, whereas the second and third rifting stages were essentially amagmatic andoccurred under humid (sub)tropical conditions. The structural style during polyphase rifting is characterizedby extensional systems involving the uppermost part of the crust, with basal faults located at a depth of 7 to10km. The Maestrat and Garraf basins developed during the Barremian–early Albian period were boundedby decakilometric normal faults with kilometric dip-slip, and were later inverted during the Paleogenecontraction, giving rise to the fold-and-thrust systems of the Iberian and Catalan Coastal chains. Verticalmovements, uplift and fault-induced subsidence, and the prevailing climate conditions were the two principalcontrols on the sedimentary record of the Iberian intraplate rift basins.