in the northern Atlantic), magmatic processes dominate.
Seismic imaging has revealed an axial magma chamber
beneath the Lucky Strike Volcano (37
18
0 N) at the
Mid-Atlantic Ridge (Singh et al., 2006), similar to that
imaged along fast-spreading ridges but limited in space
to 7 km along the axis. The architecture of slow-spread
crust typically changes along axis toward segment ends,
where it is more heterogeneous, with a mixture of
Crustal Accretion, Figure 1 Sketches of end-member crustal accretion models (modified from Kelemen et al., 1997). (a) Gabbro
glacier model. (b) Sheeted sill model of in situ formation of the lower crust by on-axis sill intrusions.
Crustal Accretion, Figure 2 (a) Simplified, interpreted, axis-parallel section through slow-spread crust (modified from Cannat et al.,
1995). (b) Sketch of crustal accretion controlled by detachment faulting (modified from Escartı ´n and Canales, 2011).
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