Skip to Main content Skip to Navigation
Journal articles

Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling

Abstract : Magmatic activity tends to concentrate at plate margins. At divergent margins, extensional tectonics provide steep conduits for magma to reach the surface. At rapidly convergent margins, such as the Andes, one might imagine that horizontal compression prevents the rise of magma. Nevertheless, volcanoes are also common. In order to study the mechanisms by which magma rises in a compressional context, we resorted to laboratory experiments, in which a brittle crust was shortened, while magma was intruding. Our model materials were (1) cohesive fine-grained silica powder, representing brittle crust, and (2) molten low-viscosity vegetable oil, representing magma. In general, horizontal shortening and injection were coeval but independent processes. Thrust faults accommodated the shortening, while overpressured oil formed hydraulic fractures. In those experiments where there was no shortening, injection resulted in a saucer-shaped intrusive body. In the other experiments, where there was shortening, oil formed a basal sill, before rising along thrust faults. Once in place, the sill lubricated the base of the model, so that arcuate thrusts formed at the leading edge of a plateau. Uplift of the plateau promoted further intrusion of oil at depth. In general, the pattern of deformation and intrusion depended on the kinematic ratio R between rates of shortening and injection. The lengths of the basal sill and plateau increased with decreasing R. On the basis of these results, we have reexamined two natural examples of magmatic complexes, which were emplaced in compressional tectonic settings, Tromen volcano in Argentina and the Boulder Batholith of Montana.
Complete list of metadatas

Cited literature [95 references]  Display  Hide  Download

https://hal-insu.archives-ouvertes.fr/insu-00155139
Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, March 30, 2016 - 8:31:28 PM
Last modification on : Thursday, December 12, 2019 - 11:34:13 AM
Long-term archiving on: : Monday, November 14, 2016 - 8:00:17 AM

File

Galland_et_al-2007-Journal_of_...
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Olivier Galland, P.R. Cobbold, Jean de Bremond d'Ars, Erwan Hallot. Rise and emplacement of magma during horizontal shortening of the brittle crust: Insights from experimental modeling. Journal of Geophysical Research : Solid Earth, American Geophysical Union, 2007, 112 (B6), pp.B06402. ⟨10.1029/2006JB004604⟩. ⟨insu-00155139⟩

Share

Metrics

Record views

392

Files downloads

332