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Abstract Volcanic seamount chains on the flanks of mid‐ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate withoutin situsampling and is further hampered by Ar40/Ar39dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast‐spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and tectonic rotation. Near‐bottom compressed high‐intensity radiated pulse, bathymetric, and sidescan sonar data collected with the autonomous underwater vehicleSentryare used to test the hypothesis that seamount volcanism is age‐progressive along the seamount chain. Although sediment on seamount flanks is likely to be reworked by gravitational mass‐wasting and current activity, bathymetric relief andSentryvehicle heading analysis suggest that sedimentary accumulations on seamount summits are likely to be relatively pristine. Sediment thickness on the seamounts' summits does not increase linearly with nominal crustal age, as would be predicted if seamounts were constructed proximal to the EPR axis and then aged as the lithosphere cooled and subsided away from the ridge. The thickest sediments are found at the center of the chain, implying the most ancient volcanism there, rather than on seamounts furthest from the EPR. The nonlinear sediment thickness along the 8°20’N seamounts suggests that volcanism can persist off‐axis for several million years.
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Models for the evolution of seamounts
SUMMARY Seamounts are volcanic constructs that litter the seafloor. They are important for understanding numerous aspects of marine science, such as plate tectonics, the volcanic melt budget, oceanic circulation, tsunami wave diffraction, tidal energy dissipation and mass wasting. Geometrically, seamounts come in many sizes and shapes, and for the purpose of modelling them for morphological, gravimetric or isostatic studies it is convenient to have simple analytical models whose properties are well known. Here, we present a family of seamount models that may be used in such studies, covering both the initial construction phase and later mass-wasting by sectoral collapses. We also derive realistic axisymmetric density variations that are compatible with observed first-order structure from seismic tomography studies.
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- Award ID(s):
- 1953499
- PAR ID:
- 10371570
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Geophysical Journal International
- Volume:
- 231
- Issue:
- 3
- ISSN:
- 0956-540X
- Page Range / eLocation ID:
- p. 1898-1916
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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