Hodgson, David Mark; (2002) Tectono-stratigraphic evolution of a Neogene oblique extensional orogenic basin, southeast Spain. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The Tabernas-Sorbas Basin is one of several elongate intramontane basins in the Betic Cordillera that formed on stretched metamorphic rocks, formed during Alpine African-Iberian compression. This study focuses on the early tectono-stratigraphic evolution of the basin from the late Serravallian to the early Messinian (12-6 Ma). During the latest Serravallian, the exhumation and erosion of the hinterland with rapid east-to-west cooling and uplift of the Nevado-Filabride Complex, was reflected by an abrupt east-to-west increase in coarse-grained sediment flux with the establishment of fan-delta sedimentation (Umbria Formation, Pollo Member, and Rambla de Indalecio Member). A major period of tectonic reorganisation in the earliest Tortonian led to the formation of a regional unconformity, a change in palaeoslope and the influx of Nevado-Filabride rock-types (Lomas Colorada Member). Continued basin subsidence, controlled by an anticlockwise change in extension (ENE-WSW), led to the deposition of submarine fans (Mizala Member) and marls with interbedded contained-flow turbidites (the Lucainena Member). The westward-stepping depocentre and a syn-sedimentary tectonic transport direction about the NE-SW, indicate subsidence was controlled by dextral oblique-extension. N-directed movement and anticlockwise rotation of the Alhamilla block led to the compressional deformation at the SE margin with low-angle normal faults reactivated as syn-sedimentary thrust faults and the formation of an angular unconformity. Growth of NE-SW trending anticlines and synclines, and a reduced basin floor gradient changed the bypassing sedimentary system (Unit A) to an aggradational, ponded system (Unit B and C). Dextral oblique-compressional conditions in the east, therefore, were coeval with a dextral oblique-extensional regime in the west during the latest Tortonian. Ponded sheet turbidites, intercalated with rare seismites, healed the topographically complex basin-floor (Unit D) and were coeval with shallow-marine carbonate sedimentation in the Sorbas area. A complex tectono-stratigraphic history of Tabernas-Sorbas Basin has been unravelled, and the basin is most accurately classified as a polyhistory basin.

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