Thrust sequences in the eastern Spanish Pyrenees

Abstract

Detailed mapping of the South Pyrenean zone in the eastern Spanish Pyrenees shows that a great number of Alpine thrusts affect the basement and the cover. The geometry of the thrust structures and their propagation sequence can be interpreted from balanced sections. The folding dies out downwards, from the higher thrust sheets to the lower ones and demonstrates a piggy-back thrusting sequence. These thrusts form a duplex. The sole thrust of this duplex is the Vallfogona thrust. The roof thrust is rooted somewhere within the Axial Zone. The thrusts climb southwards from the Axial Zone basement up into Tertiary cover sediments. These thrusts have been folded so that they now dip to the south and form the southern side of the Axial Zone antiformal stack. Locally, smaller antiformal stacks developed and produced strong folds in the higher thrust sheets. The South Pyrenean zone studied is equivalent to the Gavarnie nappe and the connection between them, below the detached South Pyrenean Central unit, may be the Nogueres zone.