Asociaciones de foraminíferos del Messiniense y Plioceno del sector norte de la Cuenca del Bajo Segura

The Messinian and Pliocene stratigraphic record of the northern sector of the Bajo Segura Basin has been separated into three main allostratigraphic units (MI, MII and P). These units are composed of continental to marine depositional systems. The aim of this paper is study the foraminiferal assemblages belonging to lagoonal and marine systems. The distribution of these foraminiferal assemblages show two significantly paleoenvironmental changes: 1) an abrupt change from marine to lagoonal foraminifer assemblages at the MI/MII boundary, related with the beginning of the Lago Mare and Terminal Complex deposition; and 2) a significant marine foraminiferal repopulation at the beginning of the Pliocene as a consequence of the marine reflooding of the Mediterranean.

Geodynamic events reconstructed in the Betic, Maghrebian, and Apennine chains (central-western Tethys)

A synthetic study has been made to identify main tectono-sedimentary and geodynamic events in central-western Tethys. For this, an interdisciplinary analysis has been performed on successions belonging to tectonic units derived from Betic-Maghrebian-southern Apennine “Flysch basin” domain. The stratigraphic records of the internal, external, and mixed successions deposited in lateral basins of different chains show very similar characters, especially regarding: (a) lithostratigraphy and ages; (b) kind and provenance of supplies (immature and supermature petrofacies from internal and external margins, respectively); (c) presence of “mixed successions” (composed of alternating internal and external petrofacies) attesting to clear palaeogeographic relationships between opposite depositional systems; and (d) timing of the deformation. In addition, specific lithofacies reveal correspondence with similar sedimentary events, such as: (1) very thick silicoclastic supply concentrated in restricted time ranges indicating the main deformational phases in the margin/basin systems; (2) levels rich in black-shales, glauconian, siliceous-producers, and volcaniclastic intercalations, widespread in the studied successions and linked to particular events at the Tethyan scale (anoxic periods, starvation-upwelling, acid-intermediate penecontemporaneous volcanic activity, respectively). Tectonic influence has also been recorded by means of unconformities and tectofacies (such as turbidites, slumps, or olisthostromes, etc.), being correlated with the main deformational phases. Similar stratigraphic and tectonic events have also been found in the Calvana unit of Val Marecchia nappe (Ligurides, northern Apennine). Correlations of stratigraphic and tectonic events support the proposal of an evolutionary geodynamic model involving the presence of a “Mesomediterranean microplate” in intermediate position during Africa-Europe convergence. The closure of central-western Tethys occasioned the Betic-Maghrebian-southern Apennine oceanic branch deformation and the birth of perimediterranean chains during middle-late Miocene.