@article {lundin_magmatism_2017, title = {Magmatism and extension rates at rifted margins}, journal = {Petroleum Geoscience}, volume = {24}, number = {4}, year = {2017}, month = {sep}, pages = {379{\textendash}392}, abstract = {Rifted margins are commonly classified as either magma-rich or magma-poor. Magma-poor margins are often implicitly related to ultraslow{\textendash}slow extension. Conversely, therefore, magma-rich margins should represent more rapid extension. Although supported by numerical modelling, these relationships are based on limited data and depend on a perhaps spurious comparison between continental margins and spreading ridges. Three case studies from the Atlantic margins are therefore presented here as a local, by no means complete, examination of this concept.Extension rates for magma-poor margins are mainly derived from offshore Iberia, while the best documented rates on magma-rich margins are probably those in the NE Atlantic. Particularly for the NE Atlantic, there is a dependence on the initial oceanic spreading rate as pre-break-up rates are very difficult to quantify. Our two southerly examples, the Central Atlantic and southern South Atlantic, are both magma-rich in parts and have been described as opening during ultraslow{\textendash}slow plate separation. Both would therefore seem to contradict the positive {\textquoteleft}rate-magmatism{\textquoteright} correlation. However, on closer examination, a wide range of initial extension rates are actually possible. This is largely due to poor constraints on break-up ages. The assumption that break-up is synchronous with flood basalt extrusion is flawed, and may have caused initial extension rates to have been significantly underestimated. Additionally, averaging between widely spaced oceanic magnetic anomalies allows for a wide range of extension rates. New, well-constrained ages and event chronologies from critical areas of conjugate margins are needed to determine whether this relationship has global validity.}, issn = {1354-0793}, doi = {10.1144/petgeo2016-158}, url = {https://doi.org/10.1144/petgeo2016-158}, author = {Lundin, Erik R. and Dor{\'e}, Anthony G. and Redfield, Thomas F.} }