Skip to Main Content
Book Chapter

Upper and lower crustal evolution during lithospheric extension: numerical modelling and natural footprints from the European Alps

By
Anna Maria Marotta
Anna Maria Marotta
1
Università degli Studi di Milano
,
Dipartimento di Scienze della Terra ‘A. Desio’, Sezione di Geofisica, Via Cicognara 7, I-20129 Milano
,
Italy
Search for other works by this author on:
Maria Iole Spalla
Maria Iole Spalla
2
Università degli Studi di Milano
,
Dipartimento di Scienze della Terra ‘A. Desio’, Sezione di Geologia and CNR-IDPA, Via Mangiagalli 34, I-20133 Milano
,
Italy
Search for other works by this author on:
Guido Gosso
Guido Gosso
2
Università degli Studi di Milano
,
Dipartimento di Scienze della Terra ‘A. Desio’, Sezione di Geologia and CNR-IDPA, Via Mangiagalli 34, I-20133 Milano
,
Italy
Search for other works by this author on:
Published:
January 01, 2009

Abstract

When continental rifting does not develop on a stable continental lithosphere, geodynamic interpretation of igneous and metamorphic records, as well as structural and sedimentary imprints of rifting-related lithospheric extension, can be highly ambiguous since different mechanisms can be responsible for regional HT–LP metamorphism. This is the case of the European Alps, where the exposure of Variscan structural and metamorphic imprints within the present-day Alpine structural domains indicates that before the Pangaea break-up, the continental lithosphere was thermally and mechanically perturbed by Variscan subduction and collision. To reduce this ambiguity, we use finite-element techniques to implement numerical geodynamic models for analysing the effects of active extension during the Permian–Triassic period (from 300 to 220 Ma), overprinting a previous history of Variscan subduction-collision up to 300 Ma. The lithosphere is compositionally stratified in crust and mantle and its rheological behaviour is that of an incompressible viscous fluid controlled by a power law. Model predictions of lithospheric thermal state and strain localization are compared with metamorphic data, time interval of plutonic and volcanic activity and coeval onset of sedimentary environments. Our analysis confirms that the integrated use of geological data and numerical modelling is a valuable key for inferring the pre-orogenic rifting evolution of a fossil passive margin. In the specific case of the European Alps, we show that a relative high rate of active extension is required, associated for example with a far extensional field, to achieve the fit with the maximal number of tectonic units. Furthermore, in this case only, thermal conditions allowing partial melting of the crust accompanying gabbroic intrusions and HT–LP metamorphism are generated. The concordant set of geological events that took place from Permian to Triassic times in the natural Alpine case is justified by the model and is coherent with the progression of lithospheric thinning, later evolving into the appearance of oceanic crust.

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Special Publications

Extending a Continent: Architecture, Rheology and Heat Budget

U. Ring
U. Ring
University of Canterbury, New Zealand
Search for other works by this author on:
B. Wernicke
B. Wernicke
California Institute of Technology, USA
Search for other works by this author on:
Geological Society of London
Volume
321
ISBN electronic:
9781862395695
Publication date:
January 01, 2009

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal