Publikationsdatum:
2020-01-23
Beschreibung:
Deep-Earth convection can be understood by studying
hotspot volcanoes that form where mantle plumes rise up
and intersect the lithosphere, the Earth’s rigid outer layer.
Hotspots characteristically leave age-progressive trails of
volcanoes and seamounts on top of oceanic lithosphere,
which in turn allow us to decipher the motion of these plates
relative to “fixed” deep-mantle plumes, and their (isotope)
geochemistry provides insights into the long-term evolution
of mantle source regions. However, it is strongly suggested
that the Hawaiian mantle plume moved ~15° south between
80 and 50 million years ago. This raises a fundamental question
about other hotspot systems in the Pacific, whether or
not their mantle plumes experienced a similar amount and
direction of motion. Integrated Ocean Drilling Program
(IODP) Expedition 330 to the Louisville Seamounts showed
that the Louisville hotspot in the South Pacific behaved in a
different manner, as its mantle plume remained
more or less fixed around 48°S latitude during that
same time period. Our findings demonstrate that
the Pacific hotspots move independently and
that their trajectories may be controlled by differences
in subduction zone geometry. Additionally,
shipboard geochemistry data shows that, in
contrast to Hawaiian volcanoes, the construction
of the Louisville Seamounts doesn’t involve a
shield-building phase dominated by tholeiitic lavas,
and trace elements confirm the rather homogenous
nature of the Louisville mantle source. Both
observations set Louisville apart from the
Hawaiian-Emperor seamount trail, whereby the
latter has been erupting abundant tholeiites (characteristically
up to 95% in volume) and which exhibit
a large variability in (isotope) geochemistry
and their mantle source components.
Materialart:
Article
,
NonPeerReviewed
Format:
text
DOI:
10.2204/iodp.sd.15.02.2013
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