The Main Ethiopian Rift (MER) has a complex structural pattern composed of southern, central, and northern segments. Ages of onset of faulting and volcanism apparently indicate a heterogeneous time‐space evolution of the segments, generally referred to as a northward progression of the rifting process. New structural, petrological, and geochronological data have been used to attempt reconciling the evolution of the distinct MER segments into a volcanotectonic scenario accounting for the propagation of the Afar and the Kenya Rifts. In this evolutionary model, extension affected the Southern MER in the early Miocene (20–21 Ma) due to the northward propagation of the Kenya Rift‐related deformation. This event lasted until 11 Ma, then deformation decreased radically and was resumed in Quaternary times. In the late Miocene (11 Ma), deformation focused in the Northern MER forming a proto‐rift that we consider as the southernmost propagation of Afar. No major extensional deformation affected the Central MER in this period, as testified by the emplacement at 12–8 Ma of extensive plateau basalts currently outcropping on both rift margins. Significant rift opening occurred in the Central MER during the Pliocene (∼5–3 Ma) with the eruption of voluminous ignimbritic covers (Nazret sequence) exposed both on the rift shoulders and on the rift floor. The apparent discrepancy between the heterogeneous propagation of the three MER segments could be reconciled by considering the opening of Central MER and the later reactivation of the Southern MER as due to a southward propagation of rifting triggered by counterclockwise rotation of the Somalian plate starting around 10 Ma.
The evolution of Neogene volcanic activity in the Central Taurus is investigated; stratigraphical and radiometric age data from the Orgup (Kayseri) basin idicate that volcanism in the area began at least as early as Upper Miocene, lasting up to prehistoric times. The volcanism maintained throughout this time interval a calcalkaline character. The diachronous end of calcalkaline volcanism along the Taurus margin is tentatively related to the differential collision between the Afro-Arabian and the Anatolian plates, probably due to an original irregular shape of the Anatolian continental margin.
Since late Miocene time, post-collisional extension of the internal parts of the Apennine
orogenic belt has led to the opening of the Tyrrhenian basin. Extensive, mainly acidic peraluminous
magmatism affected the Tuscan Archipelago and the Italian mainland during this time, building up
the Tuscan Magmatic Province as the fold belt was progressively thinned, heated and intruded by
mafic magmas. An intrusive complex was progressively built on western Elba Island by emplacement,
within a stack of nappes, of multiple, shallow-level porphyritic laccoliths, a major pluton, and a final
dyke swarm, all within the span from about 8 to 6.8 Ma. New geochemical and Sr–Nd isotopic investigations
constrain the compositions of materials involved in the genesis of the magmas of Elba Island
compared to the whole Tuscan Magmatic Province. Several distinct magma sources, in both the crust
and mantle, have been identified as contributing to the Elba magmatism as it evolved from crust-, to
hybrid-, to mantle-dominated. However, a restricted number of components, geochemically similar to
mafic K-andesites of the Island of Capraia and crustal melts like the Cotoncello dyke at Elba,
are sufficient to account for the generation by melt hybridization of the most voluminous magmas
(c. εNd(t) −8.5, 87Sr/86Sr 0.715). Unusual magmas were emplaced at the beginning and end of the
igneous activity, without contributing to the generation of these hybrid magmas. These are represented
by early peraluminous melts of a different crustal origin (εNd(t) between −9.5 and −10.0, 87Sr/86Sr variable between 0.7115 and 0.7146), and late mantle-derived magma strongly enriched in
incompatible elements (εNd(t) = −7.0, 87Sr/86Sr = 0.7114) with geochemical–isotopic characteristics
intermediate between contemporaneous Capraia K-andesites and later lamproites from the Tuscan
Magmatic Province. Magmas not involved in the generation of the main hybrid products are not volumetrically
significant, but their occurrence emphasizes the highly variable nature of crust and mantle
sources that can be activated in a short time span during post-collisional magmatism.
The Etna volcano is located in an apparently anomalous position on the hinge zone of the Apennines subduction and its Na‐alkaline geochemistry does not favour a magma source from the deep slab as indicated for the Aeolian K‐alkaline magmatism. The steeper dip of the regional foreland monocline at the front of the Apennines in the Ionian Sea than in Sicily, implies a larger rollback of the subduction hinge in the Ionian Sea. Moreover, the lengthening of the Apennines arc needs extension parallel to the arc. Therefore, the larger southeastward subduction rollback of the Ionian lithosphere with respect to the Hyblean plateau in Sicily, should kinematically produce right‐lateral transtension and a sort of vertical ‘slab window’ which might explain (i) the Plio‐Pleistocene alkaline magmatism of eastern Sicily (e.g. the Etna volcano) and (ii) the late Pliocene to present right lateral transtensional tectonics and seismicity of eastern Sicily. The area of transfer of different dip and rollback occurs along the inherited Mesozoic passive continental margin between Sicily and the oceanic Ionian Sea, i.e. the Malta escarpment.
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