Accretion Dynamics of the Oblique section of the Mid-Atlantic Ridge North of the Kane Transform Fault (23°50’N-25°15’N)

The Mid-Atlantic Ridge (MAR) north of the Kane Transform Fault (MARNOK) provides an 
ideal setting to investigate the interplay between magma supply, faulting, and lithospheric 
structure at a slow-spreading mid-ocean ridge (MOR). Along this section, two orthogonal 
segments and four oblique segments bounded by non-transform discontinuities show 
contrasting accretion styles. Orthogonal segments 1 and 6, located at the southern and 
northern ends of the study area, show symmetrical spreading, and progressive thinning of the 
crust with decreasing distance to the axis (from 8-9 km in ~1.12-Myr old lithosphere to 6-7 km 
on-axis).  These segments also display closely spaced, elongated normal faults, and their 
Mantle Bouguer anomaly (MBA) and Residual Mantle Bouguer anomaly (RMBA) are lower 
than that of the adjacent oblique segments. The lack of axial volcanic ridges in segments 1 
and 6 along with the decreasing crustal thickness towards the axis indicate a reduction in melt 
supply in recent geological time, and possible fluctuations of the magma supply on 
characteristic time scales of ~1.12 Myr in this part of the MAR. 
The oblique segments (Segments 2 to 5) show a mixed tectono-magmatic regime that reflects 
the structural complexity of the MARNOK region. Detachment faults at the inside corners of 
segments 2 and 5 along with thin crust indicate earlier asymmetrical, low-magma accretion 
typical of oblique MAR segments. Present-day magmatism forms discontinuous, sigmoidal, 
and locally focused axial volcanic ridges that resemble those observed on other oblique MOR 
segments such as Mohns ridge, and certain oblique areas of the Southwest Indian Ridge. 
Short, widely spaced faults and irregular volcanic constructions indicate that magma is 
currently contributing to plate separation. Even though the axial volcanic ridges are aligned 
with the strike of orthogonal segments 1 and 6, the melt budget of segments 2–5 does not 
appear sufficient to reorganize these segments into orthogonal spreading.  
Petrological observations reveal that melt–rock interaction is pronounced in tectonically 
dominated MARNOK domains. This result along with structural and gravity, observations 
indicating transient, localized melt focusing occurs within the MARNOK mantle. These 
findings support observations from other slow and ultraslow ridges showing that magmatic 
accretion is highly variable and controlled by mantle fertility, detachment-related cooling, and 
intermittent melt supply. Overall, the results indicate that crustal formation in the MARNOK 
region is shaped not simply by spreading rate, but by the combined influence of obliquity, melt 
availability, faulting, and thermal structure. This integrated tectono-magmatic framework 
provides new insight into how slow-spreading lithosphere evolves north of the Kane Transform 
Fault and highlights the rapid temporal and spatial variability that characterizes magmatic and 
tectonic processes at the Mid-Atlantic Ridge.