Centrifuge models simulating magma emplacement during oblique rifting Giacomo Corti a, *,MarcoBonini b , Fabrizio Innocenti a , Piero Manetti c ,GeneneMulugeta d a Dipartimento di Scienze della Terra, Universita ` degli Studi di Pisa, via S. Maria, 53, 56126 Pisa, Italy b Analogue Modelling Laboratory, CNR, Centro Studio Geologia dell’Appennino e delle Catene Perimediterranee, via La Pira, 4, 50121 Firenze, Italy c Dipartimento di Scienze della Terra, Universita ` degli Studi di Firenze, via La Pira, 4, 50121 Firenze, Italy d Hans Ramberg Tectonic Laboratory, Institute of Earth Sciences, Uppsala University, Villavagen 16, 752 36 Uppsala, Sweden Received 8 December 2000; accepted 21 May 2001 Abstract A series of centrifuge analogue experiments have been performed to model the mechanics of continental oblique extension (in the range of 0  to60  ) in the presence of underplated magma at the base of the con- tinentalcrust.Theexperimentsreproducedthemaincharacteristicsofobliquerifting,suchas(1)en-echelon arrangementofstructures,(2)meanfaulttrendsobliquetotheextensionvector,(3)strainpartitioningbetween differentsetsoffaultsand(4)faultdipshigherthaninpurelynormalfaults(e.g.Tron,V.,Brun,J.-P.,1991. Experiments on oblique rifting in brittle-ductile systems. Tectonophysics 188, 71–84). The model results showthatthepatternofdeformationisstronglycontrolledbytheangleofobliquity(),whichdetermines the ratio between the shearing and stretching components of movement. For 435  , the deformation is partitionedbetweenoblique-slipandnormalfaults,whereasfor 545  astrainpartitioningarisesbetween oblique-slipandstrike-slipfaults.Theexperimentalresultsshowthatfor 435  ,thereisastrongcoupling betweendeformationandtheunderplatedmagma:thepresenceofmagmadeterminesastrainlocalisation andareducedstrainpartitioning;deformation,inturn,focusesmagmaemplacement.Magmaticchambers form in the core of lower crust domes with an oblique trend to the initial magma reservoir and, in some cases, an en-echelon arrangement. Typically, intrusions show an elongated shape with a high length/width ratio.Innature,thispatternisexpectedtoresultinmagmaticandvolcanicbeltsobliquetotheriftaxisand arrangeden-echelon,inagreementwithsomeselectednaturalexamplesofcontinentalrifts(i.e.MainEthio- pian Rift) and oceanic ridges (i.e. Mohns and Reykjanes Ridges). # 2001 Elsevier Science Ltd. All rights reserved. 0264-3707/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII:S0264-3707(01)00032-1 Journal of Geodynamics 31 (2001) 557–576 www.elsevier.com/locate/jgeodyn * Corresponding author. Fax: +39-050-500932. E-mail address: corti@dst.unipi.it (G. Corti).