Document Detail

Modelling the rheology of MgO under Earth's mantle pressure, temperature and strain rates.
MedLine Citation:
PMID:  22237109     Owner:  NLM     Status:  In-Process    
Plate tectonics, which shapes the surface of Earth, is the result of solid-state convection in Earth's mantle over billions of years. Simply driven by buoyancy forces, mantle convection is complicated by the nature of the convecting materials, which are not fluids but polycrystalline rocks. Crystalline materials can flow as the result of the motion of defects--point defects, dislocations, grain boundaries and so on. Reproducing in the laboratory the extreme deformation conditions of the mantle is extremely challenging. In particular, experimental strain rates are at least six orders of magnitude larger than in nature. Here we show that the rheology of MgO at the pressure, temperature and strain rates of the mantle is accessible by multiscale numerical modelling starting from first principles and with no adjustable parameters. Our results demonstrate that extremely low strain rates counteract the influence of pressure. In the mantle, MgO deforms in the athermal regime and this leads to a very weak phase. It is only in the lowermost lower mantle that the pressure effect could dominate and that, under the influence of lattice friction, a viscosity of the order of 10(21)-10(22) pascal seconds can be defined for MgO.
Patrick Cordier; Jonathan Amodeo; Philippe Carrez
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-01-11
Journal Detail:
Title:  Nature     Volume:  481     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  177-80     Citation Subset:  IM    
Université Lille 1, Unité Matériaux et Transformations, UMR CNRS 8207, F-59650 Villeneuve d'Ascq, France.
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Comment In:
Nature. 2012 Jan 12;481(7380):153-4   [PMID:  22237104 ]

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