GNGTS 2021 - Atti del 39° Convegno Nazionale

129 GNGTS 2021 S essione 1.3 THE DYNAMIC EVOLUTION OF THE GULF OF ADEN: PRELIMINARY RESULTS FROM A 2D NUMERICAL MODEL A. Bollino 1 , A. Regorda 1 , R. Sabadini 1 , A. M. Marotta 1 1 University of Milan, Department of Earth Science, Milano, Italy Abstract Gulf of Aden is a young oceanic basin that offers an excellent opportunity to understand brea- kup processes during extension. Regional stress field or thermal upwelling of the asthenosphere, inherited zones of weakness and the rheological structure of the lithosphere are the factors con- tributing to the initiation of rifting and deformation of lithosphere. We use a 2D thermo-mecha- nical model to simulate the formation of oceanic crust and serpentinite due to the hydration of upwelling mantle peridotite. Our preliminary results show that: a) four main tectonic phases de- velop during rifting, each one characterized by particular distributions of velocity gradients and strain rates inside divergent crustal blocks, which allow us to determine when breakup occurs; b) the timing of mantle serpentinization is not affected by the initial thermal configuration of the system but is related to crustal thickness; c) the timing of mantle partial melting strongly depends on the thermal conditions in both lithospheric plates. Finally, the results obtained so far support the hypothesis that the Gulf of Aden developed as a slow passive rift in thin lithosphere with thick crust and that the variations in features along the passive margins could be related to lateral variations in the amount of H 2 O in the mantle, which determines the different times of mantle melting. Further analyzes are underway in order to confirm these preliminary conclusions. Corresponding author: Arcangela.bollino@unimi.it