Compiled potential field data and seismic surveys across the Eastern Brazilian continental margin integrated with new magnetometric profiles and stratigraphic configuration for Trindade Island, South Atlantic, Brazil

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ABSTRACTThis work discusses the regional geological and geophysical datasets (potential field data coupled with seismic lines) available across the Eastern Brazilian Continental Margin and addresses tectonic models that have been applied to the geological interpretation of the Vitória-Trindade Chain (VTC). New magnetic data acquired in the Trindade Island is combined with compiled petrological data and geological maps to propose a stratigraphic column with radiometric control for the volcanic sequences. The gravity and magnetic anomaly maps were integrated with regional seismic profiles extending from the continental platform towards the oceanic crust, showing the geomorphology of the Abrolhos Volcanic Complex (AVC) and the VTC. A detailed geological mapping of the Trindade Island was complemented by magnetometric profiles acquired on the island. The magmatic episodes identified in the Trindade Island within different volcano-stratigraphic sequences are, geochronologically, dated by 40Ar/39Ar method as Late Neogene to Quaternary (Pliocene/Upper Pleistocene) and indicate intrusive and extrusive igneous rocks formed on the Mesozoic (Cretaceous) oceanic crust. Models for the emplacement of these volcanic rocks on much older oceanic crust include hotspots and leaking fracture zones. The presence of flat tops as observed in the volcanic banks and seamounts along the Vitória-Trindade volcanic chain indicate abrasion of much higher volcanic edifices that now form the isolated islands in the Trindade-Martin Vaz Archipelago. Geological mapping and detailed magnetometric surveys suggest different rock properties for distinct volcanic episodes that formed the Trindade Island. The remarkable pattern of magnetic anomalies trending NE-SW in the deep-water region of the Espírito Santo Basin, eastwards of the AVC, suggests that the linear chain of volcanic edifices in the VTC may be associated with mantle anomalies caused by a hotspot or plume that was influenced by the E-W direction of leaking transform fracture zones.Abbreviation: Abrolhos Volcanic Complex (AVC); Vitória-Trindade Chain (VTC)