Abstract

Magmatic activity tends to concentrate at tectonic plate boundaries. At rapidly convergent margins, such as the Andes, intense magmatic activity is coeval with strong tectonic shortening, and some volcanoes and magmatic intrusions have been emplaced near active compressional structures, usually major thrust faults. In order to understand the links between magmatic systems and compressional deformation structures in the upper crust, we describe the structure of an active volcano (Tromen, Argentina) and an exhumed intrusion (Boulder Batholith, U.S.A.) emplaced during compressional deformation. In those examples, magmatic systems and thrust faults exhibit geometrical and chronological relationships. We also present results of experimental modelling of magma emplacement during compression. The comparison between geological examples and experiments show close similarities. That suggests that the presence of magma influences the deformation pattern in the brittle crust. The influence of deep magma bodies is also to be explored at the scale of the whole crust during the development of active margins.

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