Seismic evidences of recurrent volcanism across the North Brazilian and the Fernando de Noronha ridges – Brazilian Equatorial Atlantic Ocean

Abstract

ABSTRACT. This study, based on the interpretation of LEPLAC (the Brazilian Continental Shelf Survey Project) deep seismic lines (~16.0 s twtt), reveals for the first time across the Brazilian Equatorial Atlantic Ocean seismic evidences that buried portions of individual volcanic edifices of the North Brazilian and the Fernando de Noronha volcanic ridges are laterally coupled with a series of volcanic wedges. Our analyses evidence that these magmatic occurrences are presented as layered volcanic bodies as wide as 80 km and as thick as 1.2 s (twtt) close to the volcanic edifices. Volcanic wedges occur as layered prograding bodies stemming directly from the major volcanic edifices of both ridges. Seismic analyses also reveal that numerous layered volcanic accumulations associated to a same individual volcanic edifice may occur along variable stratigraphic levels. These occurrences indicate that the evolution of the North Brazilian and the Fernando de Noronha volcanic ridges is followed by a long history of recurrent volcanic activities that may have possibly been synchronous in distinct volcanic edifices distant apart.

Keywords: seamounts, guyots, volcanic seismic facies, volcanostratigraphy, intraplate volcanic ridges.