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Geodynamics and Basin Studies
New article in Nature

New article in Nature Communications

Researchers from the Department of Earth Science of the University of Bergen explain in a paper published in Nature Communications how exhumed mantle domes form at magma-poor continental margins and at ultra-slow mid-oceanic spreading systems controlled by frictional shear zones.

Researchers from the Department of Earth Science of the University of Bergen explain in a paper published in Nature Communications how exhumed mantle domes form at magma-poor continental margins and at ultra-slow mid-oceanic spreading systems controlled b
2-D forward geodynamic modeling of the exhumed mantle domain of the conjugate distal Galicia-Flemish Cap magma-poor rifted passive margins. This image shows the structure of the exhumed mantle domains as interpreted along the conjugate Galicia-Flemish Cap margins based on 2-D geophysical data (top and middle panels), compared with results from 2-D geodynamic modelling of a-magmatic mantle exhumation with long offset brittle normal detachment faults at the seafloor (bottom panel).
Photo:
Theunissen and Huismans, Nature Communication, 2022

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Title: Mantle exhumation at magma-poor rifted margins controlled by frictional shear zones

Abstract:

The transition zone from continental crust to the mature mid-ocean ridge spreading centre of the Iberia-Newfoundland magma-poor rifted margins is mostly composed of exhumed mantle characterized by highs and domes with varying elevation, spacing and shape. The mechanism controlling strain localization and fault migration explaining the geometry of these peridotite ridges is poorly understood. Here we show using forward geodynamic models that multiple out-of-sequence detachments with recurring dip reversal form during magma-poor rifting and mantle exhumation as a consequence of the strength competition between weak frictional-plastic shear zones and the thermally weakened necking domain beneath the exhuming footwall explaining geometry of these peridotite ridges. Model behaviour also shows that fault types and detachments styles vary with spreading rate and fault strength and confirm that these results can be compared to other magma poor passive margins such as along Antarctica-Australia and to ultra-slow mid-ocean spreading systems as the South-West Indian Ridge.    

See Theunissen and Huismans, Nature Communications, 2022 (Doi: 10.1038/s41467-022-29058-1)