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Gang Lu
October 29, 2021 @ 12:00 pm - 1:00 pm
Potential temperature and depth-dependent extension control melt volume at Atlantic volcanic margins
Breakup volcanism along rifted passive margins is highly variable in time and space. The
factors controlling magmatic activity during continental rifting and breakup are not resolved
and controversial. Here we use numerical models to investigate melt generation at rifted
margins with contrasting rifting styles corresponding to those observed in natural systems.
Our results demonstrate a surprising correlation of enhanced magmatism with margin width.
This relationship is explained by depth-dependent extension, during which the lithospheric
mantle ruptures earlier than the crust, and is confirmed by a semi-analytical prediction of
melt volume over margin width. The results presented here show that the effect of increased
mantle temperature at wide volcanic margins is likely over-estimated, and demonstrate that
the large volumes of magmatism at volcanic rifted margin can be explained by depthdependent
extension and very moderate excess mantle potential temperature in the order of
50–80 °C, significantly smaller than previously suggested.