Research Highlight: Gabriela Perlingeiro

21 April 2010

To a natural researcher such as Gabriela Perlingeiro, the very existence of a controversy as to whether plume or plate might be responsible for the hot spots across the Fernando de Noronha Ridge in eastern Brazil is sufficient to impel a commitment to settle the issue.

The island of Fernando de Noronha constitutes the eastern end of a chain of volcanic islands, seamounts and atolls, which extends roughly 650km westward along the northeastern margin of Brazil to the continental volcanic field of Mecejana, near Fortaleza.  Geochronological data and plate-tectonic reconstructions for the Atlantic suggest that this volcanism may trace the drift of the South American plate over a plume-fed hotspot currently beneath Fernando de Noronha.  However, global seismic tomography has failed to image a deep mantle plume below Fernando; accordingly other investigators have proposed alternative plume sources or even non-plume, plate-driven models.  

Gabriela, in conjunction with supervisors Prof Vasconcelos, Dr Knesel and Prof Cordani, aims to provide accurate geochronological data sufficient to establish a comprehensive high-resolution history of volcanic activity in space and time along the Ridge to test the competing plate vs plume models of the origin of this volcanic lineament.  The research methodology builds upon recent studies which have demonstrated the superior reliability and precision of a laser incremental-heating method of dating in both oceanic and continental environments. 

Prior indeterminate or incompatible results from different dating techniques may derive from sample-related issues associated with an oceanic environment wherein rock formation is susceptible to interaction with seawater or where deep submarine lavas may not completely degas due to the pressure of the overlying water column.  Laser incremental-heating studies have shown that because single fresh crystals or small unaltered chips of groundmass can be individually targeted and analyzed, the method promises to provide reliable age measurements even for partly altered rocks, allowing precise quantification of age progressions where none were previously detectible.  

For more information, contact Paulo Vasconcelos.