Premium
Physical models of magmatic intrusion during thrusting
Author(s) -
Galland Olivier,
De Bremond d'Ars Jean,
Cobbold Peter R.,
Hallot Erwan
Publication year - 2003
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2003.00512.x
Subject(s) - geology , crust , sill , petrology , intrusion , brittleness , tectonics , context (archaeology) , thrust , magma , geochemistry , seismology , volcano , paleontology , physics , thermodynamics
To investigate how magma rises through the brittle upper crust in a context of compressional tectonics, we have performed experiments on scaled physical models. Powdered silica (having a cohesion of 300 Pa and an angle of internal friction of 38°) was used to represent brittle crust. A vegetable oil (with a Newtonian viscosity of 10 −2 Pa·s at 50 °C) was used to represent magma. A moving piston shortened the models in a box, while oil was injected steadily at the base. On cooling to room temperature, the oil solidified. The resulting intrusions were thin sills, dykes and laccoliths. Their shapes and emplacement modes depended on the ratio R between rates of shortening and injection. From shapes and orientations of intrusions, we infer that hydraulic fracturing was one mechanism of emplacement. Unconsolidated intrusions strongly influenced thrust formation. On the basis of our experiments, we suggest that magmas in orogenic belts can rise along thrust faults.