4th Swiss Geoscience Meeting, Bern 2006 The rift-to-drift transition in the southern North Atlantic: A stuttering start of the MORB engine?

• Main Authors: Oliver Jagoutz, Othmar Müntener, Gianreto Manatschal, Daniela Rubatto, Igor M. Villa
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Newfoundland; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.492.823; http://geoscience-meeting.scnatweb.ch/sgm2006/SGM06_abstracts/08_OS_Min_Pet/Jagoutz_Olivier_Talk.pdf

It is generally accepted that rupturing of continents is followed by localized seafloor spreading at mid ocean ridges (MOR), which are considered, on geological time scales, to be symmetric and steady state. The continuity of this process is documented by the correspondence of crustal accretion ages and magmatic ages. While these processes are well studied at present-day MOR, little is known about how stable these systems are during their embryonic stage. Even though our understanding of the mechanisms associated with extension and rifting of continents improved significantly in the last decade (Whitmarsh et al., 2001) the processes that ultimately start the MOR basalt (MORB) engine and the switch from rifting to drifting are still poorly constrained. One of the most striking results of ODP drilling along the Iberia-Newfoundland conjugate margins was the scarcity of effusive magmatism and only minor volumes of intrusive rocks (Russell and Whitmarsh, 2003) even in areas with undisputed oceanic magnetic anomalies (Srivastava et al., 2000). This observation is in conflict with numerical melting models that generally predict large volumes of MORB type melt. The genetic and temporal relationships of alkaline and