Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

Abstract

The Betic Cordillera was formed by the collision between the Alboran Domain and the South Iberian paleomargin in the frame of the NW–SE convergent Eurasia–Nubia plate boundary. The central region is undergoing a heterogeneous extension that has not been adequately analysed. This comprehensive study addressed it by collecting structural geologic, seismologic, and geodetic data. The region west of the Sierra Nevada is deformed by the extensional system of the Granada Basin, which facilitates E–W to NE–SW extension. Moreover, the southern boundary of Sierra Nevada is affected by a remarkable N–S extension related to E–W normal to normal–dextral faults affecting the shallow crust. However, geologic and geodetic data suggest that the western and southwestern Granada Basin boundary constitutes a compressional front. These data lead to the proposal of an active extensional collapse from the uplifted Sierra Nevada region to the W–SW–S, over an extensional detachment. The collapse is determined by the uplift of the central Betics and the subsidence in the Alboran Basin due to an active subduction with rollback. Our results indicate that the central Betic Cordillera is a good example of ongoing extensional collapse in the general context of plate convergence, where crustal thickening and thinning simultaneously occur.

Active Shortening Simultaneous to Normal Faulting Based on GNSS, Geophysical, and Geological Data: The Seismogenic Ventas de Zafarraya Fault (Betic Cordillera, Southern Spain)

“…All these data point to a general model of a top-to-the-W-SW gravitational collapse over the detachment of the extensional system of the Granada Basin (Galindo-Zaldívar et al, 1996;Madarieta-Txurruka et al, 2021, 2023bRuano et al, 2004). In this regional setting, the W and SW of Granada Basin may conform to a nearly fixed boundary (Rey et al, 2001) that slows down the W-SW displacement and produces local compression (Figure 9a), as in the Main Central Thrust and the South Tibetan Detachment System (Burchfiel & Royden, 1985).…”