Continental subduction and exhumation of high-pressure rocks: insights from thermo-mechanical laboratory modelling

AbstractContinental subduction below oceanic plates and associated emplacement of ophiolite sheets remain enigmatic chapters in global plate tectonics. Numerous ophiolite belts on Earth exhibit a far-travelled ophiolite sheet that is separated from its oceanic root by tectonic windows exposing continental crust, which experienced subduction-related high pressure-low temperature metamorphism during obduction. However, the link between continental subduction-exhumation dynamics and far-travelled ophiolite emplacement remains poorly understood. Here we combine data collected from ophiolite belts worldwide with thermo-mechanical simulations of continental subduction dynamics to show the causal link between the extrusion of subducted continental crust and the emplacement of far-travelled ophiolites. Our results reveal that buoyancy-driven extrusion of subducted crust triggers necking and breaking of the overriding oceanic upper plate. The broken-off piece of oceanic lithosphere is then transported on top of the continent along a flat thrust segment and becomes a far-travelled ophiolite sheet separated from its root by the extruded continental crust. Our results indicate that the extrusion of the subducted continental crust and the emplacement of far-travelled ophiolite sheets are inseparable processes.

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Mechanical decoupling of high-pressure crustal units during continental subduction

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2008.11.019 ◽

2009 ◽

Vol 278 (1-2) ◽

pp. 13-25 ◽

Cited By ~ 15

Author(s):

N CARRY ◽

F GUEYDAN ◽

J BRUN ◽

D MARQUER

Keyword(s):

High Pressure ◽

Continental Subduction ◽

Mechanical Decoupling

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Protracted oceanic subduction prior to continental subduction: New Lu-Hf and Sm-Nd geochronology of oceanic-type high-pressure eclogite in the western Dabie orogen

American Mineralogist ◽

10.2138/am.2010.3307 ◽

2010 ◽

Vol 95 (8-9) ◽

pp. 1214-1223 ◽

Cited By ~ 31

Author(s):

H. Cheng ◽

S. A. DuFrane ◽

J. D. Vervoort ◽

E. Nakamura ◽

Y.-F. Zheng ◽

...

Keyword(s):

High Pressure ◽

Dabie Orogen ◽

Continental Subduction

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Extrusion of subducted crust explains the emplacement of far-travelled ophiolites

10.5194/egusphere-egu21-3047 ◽

2021 ◽

Author(s):

Kristóf Porkoláb ◽

Thibault Duretz ◽

Philippe Yamato ◽

Antoine Auzemery ◽

Ernst Willingshofer

Keyword(s):

High Pressure ◽

Continental Crust ◽

Plate Tectonics ◽

Oceanic Lithosphere ◽

Causal Link ◽

Combine Data ◽

Continental Subduction ◽

Ophiolite Emplacement ◽

Oceanic Plates ◽

Tectonic Windows

<p>Continental subduction below oceanic plates and associated emplacement of ophiolite sheets remain enigmatic chapters in global plate tectonics. Numerous ophiolite belts on Earth exhibit a far-travelled ophiolite sheet that is separated from its oceanic root by tectonic windows exposing continental crust, which experienced subduction-related high pressure-low temperature (HP-LT) metamorphism during obduction. However, the link between continental subduction-exhumation dynamics and far-travelled ophiolite emplacement remains poorly understood. We combine data collected from ophiolite belts worldwide with thermo-mechanical simulations of continental subduction dynamics to show the causal link between the extrusion of subducted continental crust and the emplacement of far-travelled ophiolite sheets. Our results reveal that buoyancy-driven extrusion of subducted crust triggers necking and breaking of the overriding oceanic upper plate. The broken-off piece of oceanic lithosphere is then transported on top of the continent along a flat thrust segment and becomes a far-travelled ophiolite sheet separated from its root by the extruded continental crust. Our results indicate that the extrusion of the subducted continental crust and the emplacement of far-travelled ophiolite sheets are inseparable processes.</p>

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