Geophysical characterization and 2D gravimetric modeling: Application to tectonic control of the Vitória-Trindade Ridge (VTR–ES, Brazil)

Abstract

There are numerous inquiries regarding the origin and development of the Vitória-Trindade Ridge (VTR) in eastern Brazil, a major tectonic feature composed of seamounts, guyots, banks, and islands, prompting extensive studies in the region. These investigations aim to create a more precise crustal model to aid in understanding various geological phenomena, such as the separation of South America from Africa, the interaction between continental and oceanic crusts, and the behavior of oceanic fracture zones. These zones may have served as conduits for magma feeding into the ridge and adjacent areas, or the seamounts could have formed due to a fixed mantle plume related to the West-East trend. This study focuses on exploring the tectonic structure of the region, particularly the subsurface of the VTR, utilizing geophysical data modeling techniques. This includes data from topography, gravimetric and magnetic anomalies, and analysis of reflection seismic lines. The research aims to accurately characterize the geological and geophysical context of the continental margin and some igneous features in the offshore region of the Espírito Santo and Bahia states. The anomalous hotspots correlate with pre-existing fracture zones resulting from the Mesozoic rifting of South American and African continents, which due to later tectonic episodes, have masked traces of deep-seated tectonic structures. The integration of geophysical methods, particularly gravimetry and magnetometry, when combined with reflection seismic data and 2D modeling techniques, offer insights into the geodynamic processes involved in the formation of the volcanic ridge. The results obtained showed the interference generated by magmatism in the oceanic crust and the transition zone. The seismic data allowed the visualization of the approximate geometries and interrelationships of some volcanic edifices that are compared with the Davis Bank, located in the central region of the VTR.