Plutonic processes in transitional oceanic plateau crust: Structure, age and emplacement of the South Rallier du Baty laccolith, Kerguelen Islands - Géoarchitecture : Territoires, Urbanisation, Biodiversité, Environnement Accéder directement au contenu
Article Dans Une Revue Terra Nova Année : 2020

Plutonic processes in transitional oceanic plateau crust: Structure, age and emplacement of the South Rallier du Baty laccolith, Kerguelen Islands

Construction des plutons dans une croûte océanique transitionnelle : structure, âge et mise en place du laccolithe de Rallier du Baty Sud, Iles Kerguelen

Résumé

The syenitic rocks of South Rallier du Baty Intrusive Complex (SRBIC) represent in- trusions into the oceanic plateau basalts of the south-western Kerguelen Islands. The SRBIC was previously interpreted as a typical ring complex due to magma emplace- ment with cauldron subsidence. Our new structural and geochronological data reveal that it is a laccolith built between 11.6 and 7.9 Ma by successive injections of magma sheets around the crust–mantle boundary, with an average injection rate between 0.8 and 1.4 × 10−4 km3/year. These results establish strong similarities between the SRBIC, the only recorded example of a felsic laccolith in an oceanic intraplate setting, and many continental plutons emplaced in various geodynamic setting. The SRBIC thus has the characteristics of a continental plutonic complex emplaced in an oceanic plateau crust. We postulate the critical parameter relevant to causing such similari- ties and plutonic magmatism is crustal thickness.
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Dates et versions

hal-03024359 , version 1 (25-11-2020)

Identifiants

Citer

Léandre Ponthus, Michel de Saint Blanquat, Damien Guillaume, Marc Le Romancer, Norman Pearson, et al.. Plutonic processes in transitional oceanic plateau crust: Structure, age and emplacement of the South Rallier du Baty laccolith, Kerguelen Islands. Terra Nova, 2020, 32 (6), pp.408-414. ⟨10.1111/ter.12471⟩. ⟨hal-03024359⟩
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