Research program
Relationships between anorogenic and orogenic magma sources and geodynamic implications for the Europe-Africa system.
University Co-ordinator
Università degli Studi ROMA TRE -
SCIENZE GEOLOGICHE - ROMA(RM)
Research Unit Leader
Massimo MATTEI
Description
The part of the project proposed by the research group from the University of Roma Tre will be devoted to the reconstruction of the Neogene and Quaternary geodynamic evolution of the Calabrian and the Gibraltar Arcs. Selected key-areas will be studied in detail in order to determine the age of the paleomagnetic rotations and to define the deformation mechanisms that govern the western Mediterranean volcanism.In the Calabrian Arc, available paleomagnetic data show that the outer Apenninic units underwent large anticlockwise rotations during Lower Pleistocene, suggesting the occurrence of high rates of rotations abut vertical axis. This mechanism represents the evidence of the progressive arcuature of the Calabrian Arc during Quaternary, as plausible response to the trench retreat of the Ionian subducting plate. Contemporaneously, since middle Pleistocene, in the outer area, the M. Vulture volcanic activity started, whose geodynamic meaning is still extremely controversial.In this project, detailed sampling on the Lower-Middle Pleistocene marine and lacustrine sequences will be carried out. These sequences widely cropping out in the Ofanto Basin (sub-apenninic clays sequences) and in the Sant'Arcangelo Basin (Crati and S. Lorenzo sequences) and are involved in the youngest Apenninic thrust sheets emplacements.These sedimentary sequences are adequate, for lithological and mineralogical characteristics, to paleomagnetic investigations. Moreover, these basins are located near the M. Vulture and their analysis offers, therefore, a valid contribution to the definition of the geodynamic meaning of this volcano.In the Gibraltar Arc, the present-day knowledge on the age of paleomagnetic rotations is very scarce. Therefore, paleomagnetic investigations will be addressed to the Betic and Rif chains Neogene sedimentary basins in order to define the complete evolution of the Gibraltar Arc and to constrain the age of the Arc formation. Either basins from the inner chain area (Granada Basin, Huercal-Overa Basin, Sorbas, Vera, Melilla-Nador), and those from the outer chain area (Guadalquivir, Fes-Meknes and Gharb Basins) will be sampled, in order to define the paleomagnetic rotations temporal trend in both areas and to define the geodynamic mechanism of these rotations. To pursue this aim, particular attention will be focused on the Neogene sedimentary basins (Huercal-Overa, Sorbas, Vera) located near the Capo de Gata- Murcia volcanic area in order to use the paleomagnetic results as a valid contribution to the definition of the geodynamic meaning of this volcanic area. In particular the volcanic successions will be studied for defining the main volcano-tectonic structures that control the rise of magma and their relationships with the main transcurrent faults (Carboneras, Cartagena, Palomares) which control the Neogenic-Quaternary evolution of the area.Paleomagnetic sampling will be performed in about 120 sites, with about 1300 samples, in the selected Neogene-Quaternary sequences. Sampling sites will be distributed in the different sedimentary basins, with the aim to obtain a significant number of sites in all the basins. Drilling and orientations of the cores will be done in situ with standard paleomagnetic techniques. All the cores will be than sliced in standard paleomagnetic specimens (cylinders of 25mm diameter x 22mm height), and measured in the paleomagnetic Laboratory of the University of Roma TRE. The paleomagnetic laboratory of Roma TRE is fully equipped for paleomagnetic, magnetic mineralogy, and AMS analyses, and for interpretation and presentation of paleomagnetic results. The overall set of data will be collected in tables and graphics and presented by means of structural map and geological sections both at regional and at the basin scales. Structural maps will show geometric and kinematics data of the main structural elements, the paleomagnetic declinations and the magnetic lineations obtained by AMS analyses.Furthermore, these data will be integrated with those obtained from the other reserch groups of this project in order to constrain the different geodynamic models of the tectonic evolution of Western Mediterranean.Expected results The overall paleomagnetic and volcano-tectonic data set, integrated with the results from other Research Units will allow to define: 1) The paleomagnetic rotations which occurred in each sedimentary basin and in the whole southern Apennines and the Gibraltar arc.2) The timing of the formation of the Calabrian arc and of the Gibraltar arc and their relationships with the geodynamics of the western Mediterranean.3) The relationships between the arc formation and the development of the Neogenic-Quaternary volcanism, with emphasis on the timing and the spatial relationships with the main structural elements.4) Modelling of the geodynamic evolution of the western Mediterranean region.
|
