A new collaboration will begin in November when Adrien Bronner, a PhD student at the Institut de Physique du Globe de Strasbourg, joins the team led by Jo Whittaker, on the Southern Surveyor to the Perth Abyssal Plain.
His work is part of a project called “Rift2Ridge” that deals with magnetic data from passive margins (Iberia-Newfoundland, S-Atlantic, S-Australia and Aden margins) and from ultra slow spreading ridges such as the South-West Indian ridge. Adrien's research is focused on the seaward termination of the continent. He is interested in areas where seafloor-spreading anomalies are ill defined and controversial, and he is investigating processes and sources responsible for these anomalies (especially in exhumed mantle domains) in order to better constrain rifting history and continental breakup. For that purpose, he is working in collaboration with people interested in mid-oceanic ridges as well as continental margins. The aim of this project is to better understand processes leading from continental thinning to oceanic
The first part of Adrien's PhD was focused on the Iberia-Newfoundland margins and especially the magnetic signal at the seaward edge of the ocean-continent transition. A model has been proposed based on forward modeling of magnetic anomalies constrained by seismic refraction and drill-hole data. It has been shown that the main anomaly, the J anomaly in the Newfoundland basin (NB) and the Iberia Abyssal Plain (IAP) can be explained by underplated mafic material and surface lava flows produced by a ~112 Ma event of excess magma which finally resulted in crustal breakup and seafloor spreading. Thus, the J anomaly does not correspond to the beginning of the M sequence of seafloor spreading anomalies in the IAP and NB but is interpreted as a “breakup anomaly” which marks the edges of the “true” oceanic crust. This work is currently under review at Nature Geoscience and constitutes the major part of Adrien's PhD research up to now. This working hypothesis developed here has to be tested at different other margins that is why he is really interested in the study of the Perth Abyssal Plain.
