Publication Date:
2015-06-03
Description:
Ocean islands, seamounts and volcanic ridges are thought to
form above mantle plumes.Yet, this mechanism cannot explain
many volcanic features on the Pacific Ocean floor1 and some
might instead be caused by cracks in the oceanic crust linked to
the reorganization of plate motions1–3. A distinctive bend in the
Hawaiian–Emperor volcanic chain has been linked to changes
in the direction of motion of the Pacific Plate4,5, movement of
the Hawaiian plume6–8, or a combination of both9. However,
these links are uncertain because there is no independent
record that precisely dates tectonic events that a�ected the
Pacific Plate. Here we analyse the geochemical characteristics
of lava samples collected from the Musicians Ridges, lines
of volcanic seamounts formed close to the Hawaiian–Emperor
bend. We find that the geochemical signature of these lavas
is unlike typical ocean island basalts and instead resembles
mid-ocean ridge basalts. We infer that the seamounts are
unrelated to mantle plume activity and instead formed in an
extensional setting, due to deformation of the Pacific Plate.
40Ar/39Ar dating reveals that the Musicians Ridges formed
during two time windows that bracket the time of formation
of the Hawaiian–Emperor bend, 53–52 and 48–47 million years
ago.We conclude that the Hawaiian–Emperor bendwas formed
by plate–mantle reorganization, potentially triggered by a
series of subduction events at the Pacific Plate margins.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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