Distribution of seamounts in the North Atlantic

The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges

“…The most recent investigation of off-axis seamounts in the North Atlantic was by Epp and Smoot (1989), who hypothesized that seamounts are only built where plume material is injected at the ridge axis. From their study, Epp and Smoot (1989) concluded that no seamounts are formed at the ridge axis between the Kane and Atlantis Fracture…”

“…Volcanism leading to the formation of the seamounts on the flanks of the East Pacific Rise is thought to be separate from that occurring at the ridge axis (Scheirer and Macdonald, 1995). In comparison, seamounts in the Atlantic are observed both at the axis of the slow-spreading Mid-Atlantic Ridge (MAR) and on its flanks (e.g., Litvin and Rudenko, 1973;Batiza et al, 1989;Epp and Smoot, 1989;Cann, 1990, 1992;Sempere et al, 1993). Surprisingly little is known about how volcanoes generated at the MAR are modified by faulting as crust is uplifted from the ridge axis to the crest of the rift mountains.…”

“…Even less is known about abundances, size distributions, and spatial locations of any volcanic remnants. Furthermore, there are few studies (Batiza et al, 1989;Epp and Smoot, 1989) comparable to those in the Pacific to provide information about the construction of off-axis volcanoes in the slowly spreading crust of the Atlantic, despite its importance to understanding how magma is supplied spatially and temporally to the crust during its formation and evolution.…”

Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

“…This pattern may be controlled by focusing of mantle upwelling and magmatic accretion near segment midpoints, as has been suggested by geodynamic experiments [Whitehead et al, 1984] The off-axis population of seamounts on the MAR has been little studied and is poorly understood. A study of classified U.S. Navy bathymetry by Epp and Smoot [1989] suggested that no seamounts with relief greater than ---100 m would be found off axis in the North Atlantic south of---30øN. A study of the rift valley and ridge flanks in the South Atlantic at 26øS by Batiza et al [ 1989] documented 50 off-axis seamounts with heights >50 m on ---1-7 Ma crust and 38 seamounts on crust younger than ---1 Ma.…”

“…At fast spreading ridges such as the East Pacific Rise (EPR), near-circular submarine volcanoes (seamounts) are found only rarely at the rise axis but are abundant on the rise flanks [e.g., Searle, 1983 tle is known about off-axis volcanism [e.g., Batiza et al, 1989;Epp and Smoot, 1989], despite its importance to understanding spatial and temporal supply of magma to the crust during its formation and evolution. Moreover, the processes that modify axial seamounts as they are transported to the ridge flanks are poorly understood, and the resulting abundances, size distributions, and locations of the volcanic edifice remnants have not been quantified.…”