Heat flow modelling of the Punta del Este Basin (offshore Uruguay) and its correlation with structural crustal domains

Abstract

The Punta del Este Basin is located at the offshore of Uruguay, and it is considered an underexplored basin with a high potential for holding hydrocarbon plays. Geologically, it constitutes an aborted rift related to the Gondwana fragmentation process, and subsequent opening of the Atlantic Ocean (Upper Jurassic - Lower Cretaceous). The stratigraphic and tectonic evolution comprises four phases from the Paleozoic pre-rift stage to present-day post-rift stage (Neogene/Quaternary). Due to the estimated hydrocarbon potential of this basin, exploratory activities have been intensified in the last decades, based on the acquisition of a significant amount of geophysical data which allowed a better comprehension of the basin's geology. Previous studies related to this basin were mainly oriented to the stratigraphy, structural framework, and petroleum systems comprehension. This research is focused on the thermal evolution of the Punta del Este Basin and its correlation with the crustal geological structure. For this purpose, a heat flow model was developed in order to understand thermal evolution through geological time. A 2D heat flow modelling based on pseudo wells was carried out to research and reconstruct the paleo heat flow. Bottom-hole temperatures (BHTs), seabed heat flow measurements, and Moho discontinuity depth interpretations have been employed in the reconstruction of heat flow evolution through time. A structural analysis based on seismic interpretation allowed to identify the Moho discontinuity and define four crustal domains in the study area: proximal (unattenuated crust), necking, hyperextended (stretched and thinned transition crust), and oceanic crust. The thermal model shows a strong correlation between heat flow and crustal thickness. In this way, the proximal domain develops low heat flow values while the distal sector shows higher values, due to the strong influence of the rifting event in crust thinning.