La evolución geodinámica de la Cuenca Catalano-Balear y áreas adyacentes desde el Mesozoico hasta la actualidad

E. ROCA

Abstract


The Catalan-Balearic basin is a late Oligocene to recent sedimentary basin located between the inner parts of Betic-Baleanc thrust belt (located beneath the present Algerian basin) and the ensemble Iberian Chain-Ebro basin. Partially incorporated into the Early to Middle Miocene Betic-Balearic thrust belt, the Catalan-Balearic basin inclndes, therefore, not only the eastern Iberian zones affected by extensional processes (Valencia trough, Catalan Coastal Ranges and southeastern Iberian Chain), but also the externa1 parts of the Betic-Balearic orogen (Balearic Promontory).

From a regional point of view, the Catalan-Balearic basin correponds to the southwestern prolongation of the oceanic Liguro-Provencal Basin and, in the areas not very affected by the Betic-Baleanc compressive structures, it is characterized by a highly attenuated continental cmst. Up to now, the main features of the Catalan-Balearic basin have been attempted to be explained just from the geodynamic processes that created the basin.

In order to recognize the role played by the geodynamic processes that affected the Catalan-Balearic Basin previously to its formation, the Triassic up to present evolution of the area occupied by the basin is analysed in this article. From this analysis, three main stages could be distinguished: a) a first Mesozoic stage, in which the area was submitted to extensional processes that generated wide basins and alkaline volcanics; b) a second Palaeogene stage with predominance of compressive processes that gave nse to complex fold-and-thrust belts; and c) a third late Oligocene-Neogene stage, very complex, in which the Catalan-Balearic Basin was formed in reponse to both compressive (late Oligocene-Middle Miocene building of the Betic-Balearic fold-andthrust belt) and extensional geodynamic processes (late Oligocene-Early Miocene rifting phase and post-Middle Miocene extensional collapse of the Betic-Balearic orogen).

The present structure of the area is mainly related to the last late Oligocene-Neogene compressive and extensional processes. Nevertheless, the progressive unfolding of a crustal cross-section through the whole Catalan-Balearic Basin denotes that the structures which were formed during the Mesozoic, determined not only the geometric features of the Palaeogene compressive deformation, but also those of the late Oligocene-Neogene extensional deformation that created the Catalan-Balearic Basin. In this sense, the analysis of the differentiated Mesozoic and Cenozoic evolutionary stages shows that: i) the main Cenozoic deformations are located along the margins of the previous Mesozoic basins, in snch a way that most of the faults active during the Cenozoic resulted from the reactivation of the normal faults which bounded the previous Mesozoic basins; ii) tbe Catalan-Baleanc Basin coincides in large measure with the area covered by the Catalan and Columbrets Mesozoic basins; iii) the cnistal thinning shown by the Catalan-Balearic Basin, could be partly inhented from the Mesozoic extension.



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