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Composición modal de las arenas de la Cuenca del Guadalquivir: evaluación de su procedencia

DOI: 10.3989/egeol.90465-6467

Keywords: Sands , Provenance , Recycling , Guadalquivir basin , Spain , Arenas , Procedencia , Reciclado , Cuenca del Guadalquivir , Espa a

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Abstract:

The sedimentation of the Guadalquivir neogene basin between Córdoba and Sevilla towns gave place to a thick marly succession which included several sandstone units: Arenas Basales, Arenas de Ubeda, Arenas del Guadalquivir, Arenas de Ecija, Arenas de Cuesta el Espino (all of them of upper Tortonian age), Arenas de Guadarcázar, Calcarenitas de Carmona (both of Messinian age) and pliocene sands. Arenas Basales have a lithic composition, showing high percentages of metamorphic rock fragments, and derived from metamorphic complexes of the paleozoic Macizo Hespérico located in the N of the basin. Arenas del Guadalquivir and Arenas de Ecija are litharenites and sublitharenites; their rock fragments are mainly carbonatic and derived from neogene sandy formations that cropped out in the N because of the progressive reduction of the basin. Arenas de Ecija derived from the betic mantles that were emplaced in the S of the basin at that time. Arenas Basales and Arenas del Guadalquivir are plataform deposits and Arenas de Ecija are sediments in subsea fans. Finally, Arenas de Guadarcázar and the pliocene sands are quartzarenites and sublitharenites and derived from the underlying sandy formations. The high compositional and textural maturity of Arenas de Guadarcázar was due to the reworking of these sands in a beach environment. The succession reflects an initial stage with first cycle contributions of metamorphic rocks from a stable craton and a later stage in which the source area is formed of sedimentary rocks related to a recycled orogen. In the eastern part of the basin Arenas del Guadalquivir and Arenas de Ecija are litharenites whilst the Arenas de Cuesta el Espino are sublitharenites; the former derived from a recycled orogen, and the latter from a continental block or a stable craton. The compositional evolution of the sands in this side of the basin could indicate a basin edge zone. La sedimentación de la cuenca neógena del Guadalquivir entre las provincias de Córdoba y Sevilla está formada por una potente sucesión margosa en la que se intercalan varias unidades arenosas que, de base a techo, se denominan: Arenas Basales, Arenas de Ubeda, Arenas del Guadalquivir, Arenas de Ecija, Arenas de Cuesta el Espino (todas ellas de edad Tortoniense superior), Arenas de Guadarcázar, Calcarenitas de Carmona (de edad Messiniense) y arenas pliocenas. Arenas Basales tienen una composición lítica, con alto porcentaje en fragmentos de roca metamórficos, y proceden de los complejos metamórficos del Macizo Hespérico paleozoico situado al N de la cuenca. Arenas del Guadalquivir

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