GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.3 GNGTS 2024 The gravitatonal signature of the dynamics of oceanizaton in the Gulf of Aden A. M. Marota 1 , R. Barzaghi 2 , A. Bollino 1 , A. Regorda 1 , R. Sabadini 1 1 Department of Earth Sciences Ardito Desio, Universit`a degli Studi di Milano, Milano, Italy 2 Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy We perform a new gravity analysis in the Gulf of Aden with the aim of fnding new constraints on the geodynamic evoluton of the area. Our analysis is developed within the frame of the recent GO_CONS_GCF_2_TIM_R6 global gravity model soluton (Brockmann et al., 2021) that refects the Earth’s statc gravity feld as observed by GOCE (Gravity feld and steady-state Ocean Circulaton Explorer). We analyzed the soluton at diferent harmonic degrees, to account for diferent depths and dimensions of the sources. Terrain correcton has been performed by means of a spherical tesseroidal methodology (Marota and Barzaghi, 2017) and the obtained corrected Geodetc Residual Gravitaton has been compared to the Model Residual Gravitaton predicted by means of a 2D visco-plastc fnite element thermo-mechanic model that simulates the dynamics of the Gulf of Aden, from rifing to oceanizaton. In order to perform the comparison between observed and predicted gravitatonal features, data have been extracted along fve profles crossing the Gulf of Aden at diferent sectors, from the south-east to the north west. Via the Model Residual Gravitaton we reproduce its geodetc counterpart, obtaining a characteristc hat-shaped patern, with a central plateau portraying the highest values, fanked by two regions where the residual gravitaton diminishes, fnally reaching the lowest values at the far contnental domains. The maximum variatons of the residual gravitaton values, from ridge to contnental domain, range between 280 and 420 mGal and the steepest decrease occurs over distances of 200 km for the thick crust model and of 100–150 km for the thin crust model. Finally, the comparison between Geodetc and Model Residual Gravitaton allows to further constrain the dynamics of the Gulf of Aden oceanizaton occurring by a slow passive rif of a hot 150 km thick lithosphere characterized by an inital 40 km thick crust.