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Poster

The plume head - lithosphere interactions near intracontinental plate boundaries

Abstract : Zones of plum-continental lithosphere interactions (PLI) are often located near intra-plate boundaries, in particular, near the boundaries between younger (e.g., orogenic) plates and older plates (Archean West Africa, Australian craton, Pannonian –Carpathian system). These interactions have important consequences both for tectonic and mineralogical evolution. For example, Archean metallogenic crisises at the boundaries of the West African and Australian cratons coincide with the presumed plum events. Yet, crustal and lithospheric signatures of PLI appear to be strongly influenced by lithosphere rheology and structure, which requires a through account for lithosphere in plum models. We study this problem using a numerical model that incorporates realistic visco-elasto-plastic stratified lithosphere with free a surface. The results show that lateral heterogeneities may have following effects on PLI: (A) horizontal plume head flattening is blocked from one side by cold vertical boundary of the craton, leading to crust – mantle decoupling, stress concentration andfaulting at the cratonic margin; (B) return flow from the plum head results in subvertical down-thrusting of the lithosphere at the cratonic margin providing sharp subvertical “cold” boundaries down to the depths of 400 km; (C) the asymmetric plum head flattening towards the younger plate is followed by simultaneous extension and mantle thinning in the middle of the plate and down-thrusting both at the cratonic border and at the opposite border of the young plate; (D) topographic signatures of the PLI show basin-scale uplifts and subsidences. Rayleigh-Taylor instabilities that develop around the plume head, provide a mechanism for crustal delamination. Lateral flow of mantle lithosphere, from plume head to the base of the craton suggests a new mechanism for crustal growth, where surface magmatism is not required. Lithospheric faulting at cratonic edges and enhanced magmatic activity could explain the apparent plumerelated metallogenic crises, as suggested for West Africa and Australia. PLI can explain a number of key phenomena such as simultaneous occurrence of climax of extension of the young plates/segments and climax of compression in the surrounding belts.
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https://hal-brgm.archives-ouvertes.fr/hal-01133062
Contributeur : Laurent Guillou-Frottier <>
Soumis le : mercredi 18 mars 2015 - 14:33:28
Dernière modification le : jeudi 21 mars 2019 - 14:16:26
Archivage à long terme le : : lundi 22 juin 2015 - 07:08:53

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  • HAL Id : hal-01133062, version 1

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Evgenii Burov, Laurent Guillou-Frottier. The plume head - lithosphere interactions near intracontinental plate boundaries. EGU 2006, General Assembly, Apr 2006, Vienna, Austria. ⟨hal-01133062⟩

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