Structure of an intraplate fold-and-thrust belt: The Iberian Chain. A synthesis

Abstract

The Iberian Chain is a complex intraplate fold-and-thrust belt resulting from the convergence between the Eurasian, Iberian and African plates during the late Eocene to the Miocene. The main trend of its contractional structures is NW-SE, but E-W, NE-SW and N-S-trending structures are also present. The boundaries of the chain with its surrounding foreland basins are always thrusts. The North-Iberian Thrust separates the chain from the Ebro Basin to the North, while the Serrania de Cuenca Thrust makes the SE boundary of the chain, separating it from the Tajo Basin and La Mancha foreland areas. Between these thrusts, the contractional structure is basement-involved, while South of the Serrania de Cuenca Thrust only Mesozoic and Cenozoic rocks are involved in the thrust-system, detached in the evaporitic Triassic materials. Two parts can be differentiated considering the major structure of the chain. The western and central areas hold two major anticlinoriums separated by the Almazan Synclinorium. East of the Teruel Depression, E-Wstriking N-verging thrusts in the North, and NW-SE-striking S-verging thrusts in the center and South are the dominant structures. The crust thickened during the Cenozoic contraction generating a mean crustal thickening of about 5km. The horizontal shortening obtained from cross-sections is 32km, and from a density-gravity section of 57.5km. These two values may be considered end values. The relief of the Iberian Chain has a strong areal coincidence with the contractional structures and the thickened crust, indicating that they are genetically related.