Ladinian carbonates of the Cabo Cope Unit (Betic Cordillera, SE Spain): a tethys-maláguide palaeogeographic gateway

Abstract

The Cabo Cope Unit, which outcrops east of Aguilas (Murcia), belongs to the Malaguide tectonic Complex (Betic Internal Zone) and displays stratigraphic characteristics of particular interest, including Triassic bioclastic carbonate beds which are not common in the Malaguide units. Biostratigrafic fossils have been found in these beds and may correlate with Triassic alpine biofacies. Alpine fauna fossils only appeared in those palaeogeographic units of the Internal Zone of the Cordillera referred to as Alpujarride units, while the influence of the Sephardic faunal province is evident in almost all the cordillera. For these reasons it is noteworthy that new alpine fauna fossils have been found in an Internal Zone unit in which relevant fossils rarely appear. The Triassic succession of the unit studied in this paper can be subdivided into two members: a lower one, which is clastic and contains thick gypsum beds, and an upper one, consisting of carbonate rocks. The lower member has been interpreted as a fluvial-coastal deposit. The upper member is interpreted as a sequence of carbonate ramp deposits. This ramp evolved into a shallow platform with tidal flats typical of a coastal zone. The bivalve fossilsDaonella cf.lommeli (Wissmann) and “Posidonia” sp. have been found in the carbonate member, along with the conodontSephardiella mungoensis (Diebel). These fossils are of the Late Ladinian age and have been found only in this outcroup of the Betic Cordillera. The presence of this fossil assemblage, which belongs to the alpine faunal province, indicates a connection during the Late Ladinian between the Tethys sea and this area of the Malaguide palaeogeographic domain. The palaeogeographic location of the Cabo Cope Unit during the Middle Triassic was at the south-easternmost part of the Betic Basin, implying that the connection between the Tethys and the Betic Basin was established in the easternmost domains of the basin.