Seafloor photo-geology and sonar terrain modeling at the 9°N overlapping spreading center, East Pacific Rise
Abstract
A fundamental goal in the study of mid-ocean ridges is to understand the relationship
between the distribution of melt at depth and seafloor features. Building on geophysical
information on subsurface melt at the 9°N overlapping spreading center on the East
Pacific Rise, we use terrain modeling (DSL-120A side scan and bathymetry), photo-geology
(Jason II and WHOI TowCam), and geochemical data to explore this relationship. Terrain
modeling identified four distinct geomorphic provinces with common seafloor characteristics
that correspond well to changes in subsurface melt distribution. Visual observations
were used to interpret terrain modeling results and to establish a relative seafloor
age scale, calibrated with radiometric age dates, to identify areas of recent volcanism.
On the east limb, recent eruptions in the north are localized over the margins of
the 4 km wide asymmetric melt sill, forming a prominent off-axis pillow ridge. Along
the southern east limb, recent eruptions occur along a neovolcanic ridge that hugs
the overlap basin and lies several kilometers west of the plunging melt sill. Our
results suggest that long-term southward migration of the east limb occurs through
a series of diking events with a net southward propagation direction. Examining sites
of recent eruptions in the context of geophysical data on melt distribution in the
crust and upper mantle suggests melt may follow complex paths from depth to the surface.
Overall, our findings emphasize the value of integrating information obtained from
photo-geology, terrain modeling, lava geochemistry and petrography, and geophysics
to constrain the nature of melt delivery at mid-ocean ridges. Key Points Terrain modeling
and photogeology show links between eruptions and crustal melt Eruptions above 4-km
wide melt sill occur only above sill's margins Terrain modeling found four provinces
that differ from classic tectonic view of OSC © 2013 The Authors. Geochemistry, Geophysics,
Geosystems published by Wiley Periodicals, Inc. on behalf of American Geophysical
Union.
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https://hdl.handle.net/10161/8325Published Version (Please cite this version)
10.1002/2013GC004858Publication Info
Klein, Emily M; White, Scott M; Nunnery, James Andrew; Mason-Stack, Jessica L; Wanless,
V Dorsey; Perfit, Michael R; ... Ridley, W Ian (2013). Seafloor photo-geology and sonar terrain modeling at the 9°N overlapping spreading
center, East Pacific Rise. Geochemistry, Geophysics, Geosystems, 14(12). pp. 5146-5170. 10.1002/2013GC004858. Retrieved from https://hdl.handle.net/10161/8325.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Emily M. Klein
Professor
Dr. Klein's research focuses on the geochemistry of oceanic basalts, using diverse
tools of major, trace and isotopic analyses. Her research involves sea-going expeditions
to sample and map the ocean floor.

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