Publication Date:
2021-01-27
Description:
A variety of atypical plume-like structures and focused upwellings that are not rooted in the lower mantle
have recently been discussed, and seismological imaging has shown ubiquitous small-scale convection in the
uppermost mantle in regions such as the Mediterranean region, the western US, and around the western
Pacific. We argue that the three-dimensional return flow and slab fragmentation associated with complex
oceanic subduction trajectories within the upper mantle can generate focused upwellings and that these may
play a significant role in regional tectonics. The testable surface expressions of this process are the outsidearc
alkaline volcanism, topographic swell, and low-velocity seismic anomalies associated with partial melt.
Using three-dimensional, simplified numerical subduction models, we show that focused upwellings can be
generated both ahead of the slab in the back-arc region (though ~five times further inward from the trench
than arc-volcanism) and around the lateral edges of the slab (in the order of 100 km away from slab edges).
Vertical mass transport, and by inference the associated decompression melting, in these regions appears
strongly correlated with the interplay between relative trench motion and subduction velocities. The upward
flux of material from the depths is expected to be most pronounced during the first phase of slab descent into
the upper mantle or during slab fragmentation. We discuss representative case histories from the Pacific and
the Mediterranean where we find possible evidence for such slab-related volcanism.
Description:
Published
Description:
54-68
Description:
3.3. Geodinamica e struttura dell'interno della Terra
Description:
JCR Journal
Description:
reserved
Keywords:
subduction
;
magmatism
;
upper mantle convection
;
geodynamic modeling
;
04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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