The Miocene sedimentary cover of the Mula-Gebas Basin: Internal-External Zone Boundary of the Betic Cordillera, South Spain

The Sierra Espuña and the Mula-Gebas intramontane basin, SE Spain, represent the Internal-External Zone Boundary (IEZB) of the eastern Betic Cordillera. The Miocene infill of this basin seals the IEZB and is mainly derived from the Internal Zone. This deposition is coeval with a Late Miocene volcanism. Therefore, the study of these sediments is crucial for the source-area provenance, sorting and recycling, paleoclimate, weathering, unroofing and tectonic processes, during the intramontane basins developing of the western peri-Mediterranean Chains. Sandstone detrital modes, and chemical and mineralogical compositions of mudrocks were arranged in two sedimentary cycles: (1) the middle Burdigalian-early Langhian, and (2) the middle Tortonian-early Messinian. The quartzolithic to feldspathic lithoarenite infer the erosion from a lithic-transitional recycled to transitional-quartzose recycled orogen, since low-medium grade metamorphic lithics and rare coeval volcanics with andesitic, andesitic-dacitic and rhyodacitic-rhyolitic sources are present. The mudrocks reveal a felsic (granitic-gneiss) source with a minor mafic input in the Upper Miocene. A shallow burial history and low thermal conditions (<~50 °C) has been also evidenced. Moreover, the paleoclimate changed from warm and/or wet during the Middle Miocene to cold/arid in the Late Miocene. • Miocene Mediterranean Sea and intramontane basins opening • The provenance, paleoweathering and paleoclimatic features were characterized. • Sandstones from a lithic-transitional- to quartzose-recycled orogen • Mudstones are mainly derived from a felsic source with a minor mafic input. • Comparison with similar Miocene basins at western Mediterranean scale