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Impact of the Juan Fernandez ridge on the Pampean flat subduction inferred from full waveform inversion
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  • Yajian Gao,
  • Xiaohui Yuan,
  • Benjamin Heit,
  • Frederik Tilmann,
  • Dirk Philip van Herwaarden,
  • Solvi Thrastarson,
  • Andreas Fichtner,
  • Bernd Dieter Schurr
Yajian Gao
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)

Corresponding Author:yjgao@gfz-potsdam.de

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Xiaohui Yuan
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
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Benjamin Heit
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
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Frederik Tilmann
Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ)
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Dirk Philip van Herwaarden
ETH Zurich, Switzerland
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Solvi Thrastarson
ETH Zurich, Switzerland
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Andreas Fichtner
ETH Zurich, Switzerland
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Bernd Dieter Schurr
Deutsches GeoForschungsZentrum GFZ
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Abstract

A new seismic velocity model for the south Central Andes is derived from full waveform inversion, covering the Pampean flat and adjacent Payenia steep subduction segments. Strong focused crustal low-velocity anomalies indicate partial melts in the Payenia segment along the volcanic arc, whereas weaker low-velocity anomalies covering a wide zone in Pampean possibly indicates remnant melts in the past. Thinning and tearing of the flat Nazca slab below the Pampean is inferred by gaps in the high-velocity slab along the inland projection of the Juan-Fernandez-Ridge. A high-velocity anomaly in the upper mantle below the flat slab is interpreted as a relic Nazca slab segment, which indicates an earlier slab break-off during the flattening process, triggered by the buoyancy of the Juan-Fernandez-Ridge. In Payenia, large-scale low-velocity anomalies atop and below the re-steepened Nazca slab are associated with the re-opening of the mantle wedge and sub-slab asthenospheric flow, respectively.
16 Nov 2021Published in Geophysical Research Letters volume 48 issue 21. 10.1029/2021GL095509