Hostname: page-component-5c6d5d7d68-txr5j Total loading time: 0 Render date: 2024-08-30T15:05:46.421Z Has data issue: false hasContentIssue false
  • English
  • Français

Analogue scale models of pluton emplacement during transpression in brittle and ductile crust

Published online by Cambridge University Press:  07 October 2019

Keith Benn ,
Francis Odonne ,
Sharon K. Y. Lee  and
Ken Darcovich
Keith Benn
Affiliation:
Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, University of Ottawa, Ottawa, Ontario K1N6N5, Canada e-mail:KBENN@uottawa.ca
Francis Odonne
Affiliation:
Equipe de Petrophysique et Tectonique (UMR CNRS 5563), Université Paul-Sabatier, 31400 Toulouse, France
Sharon K. Y. Lee
Affiliation:
Department of Earth Sciences, University of Ottawa, Ottawa, Ontario K1N6N5, Canada
Ken Darcovich
Affiliation:
National Research Council of Canada ICPET, Ottawa, Ontario K1A0R6, Canada
Get access Rights & Permissions [Opens in a new window]

Abstract

ABSTRACT:

Analogue experiments were used to investigate pluton emplacement during transpression in a layered crust. Models consisted of (1) a silicone gum-PbO suspension as analogue magma, (2) a silicone gum-Pb suspension as a basal ductile layer, and (3) an overlying sand pack representing brittle crust. The models were transpressed at 3 mm/hr causing the extrusion of the analogue magma from a progressively closing slot, and its emplacement into the ductile layer. The thicknesses of the layers were critical in controlling the shapes of intrusions and the structures that developed in the brittle overburden. Thicker sand packs led to flattened, symmetrical laccolith-shaped intrusions and the nucleation of one oblique thrust in the sand pack above the extremity of the intrusion. Thinner sand packs led to thicker, asymmetrical laccolith-like intrusions with uplift of the overburden on an oblique thrust, and the formation of a shallow graben in the extrados of a bending fold. Reducing the thickness of the basal ductile layer resulted in a larger number of shear zones in the sand pack, and structural geometries approaching those produced in experiments involving only a brittle analogue crust and no ductile layer. Shear zones in the sand pack were localised by intrusions, and also played a key role in displacing analogue brittle crust to make space for intrusions. The results suggest that tectonic forces may play an important role in displacing blocks of crust during pluton emplacement in transpressional belts. They also suggest that pluton shapes, and the geometries and kinematics of emplacement-related shear zones and faults, may depend on the depth of emplacement. In nature, depending on the structural level exposed in the map plane, faults and shear zones that helped make space for emplacement may not appear to be spatially associated with the pluton.

Keywords

experimentplutonsstructuresyntectonic
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 91 , Issue 1-2: Fourth Hutton Symposium: The Origin of Granites and Related Rocks , 2000 , pp. 111 - 121
Copyright
Copyright © Royal Society of Edinburgh 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anma, R. & Sokoutis, D. 1997. Experimental pluton shapes and tracks above subduction zones. In Bouchez, J. L., Hutton, D.H.W. & Stephens, W. E. (eds) Granite: from segregation of melt to emplacement fabrics, 319–34. Dordrecht: Kluwer Academic Publishers.Google Scholar
Benn, K., Home, R. J., Kontak, D. J., Pignotta, G. & Evans, N. G. 1997. Syn-Acadian emplacement model for the South Mountain Batholith, Meguma Terrane, Nova Scotia: Magnetic fabric and structural analyses. Geological Society of America Bulletin 109, 1279–93.Google Scholar
Benn, K., Odonne, F. & de Saint Blanquat, M. 1998. Pluton emplacement during transpression in brittle crust: new views from analogue experiments. Geology 36, 1079–82.Google Scholar
Benn, K., Roest, W. R., Rochette, P., Evans, N. G. & Pignotta, G. S. 1999a. Geophysical and structural signatures of syntectonic batholith construction: the South Mountain Batholith, Meguma Terrane, Nova Scotia. Geophysical Journal International 136, 144–58.Google Scholar
Benn, K., Odonne, F. & de Saint Blanquat, M. 1999b. Pluton emplacement during transpression in brittle crust: new views from analogue experiments: Reply. Geology 27, 671.Google Scholar
Brown, M. & Solar, G. S. 1998. Granite ascent and emplacement during contractional deformation in convergent orogens. Journal of Structural Geology 20, 1365–93.Google Scholar
Brown, M. & Solar, G. S. 1999. The mechanism of ascent and emplacement of granite magma during transpression: a syntectonic granite paradigm. Tectonophysics 312, 1–33.Google Scholar
Byerlee, J. 1978. Friction of rocks. Pure and Applied Geophysics 116, 615–26.Google Scholar
Castro, A. 1987. On granitoid emplacement and related structures. A review. Geologische Rundschau 76, 101–24.Google Scholar
Collins, W. J. & Sawyer, E. W. 1996. Pervasive granitoid magma transfer through the lower-middle crust during non-coaxial compressive deformation. Journal of Metamorphic Geology 14, 565–79.Google Scholar
Cruden, A. R. & Launeau, P. 1994. Structure, magnetic fabric and emplacement of the Archean Lebel Stock, SW Abitibi Greenstone Belt. Journal of Structural Geology 16, 677–91.Google Scholar
Davidson, C., Schmid, S. M. & Hollister, L. S. 1994. Role of melt during deformation in the deep crust. Terra Nova 6, 133–42.Google Scholar
Davy, P., Hansen, A., Bonnet, E. & Zhang, S. Z. 1995. Localization and fault growth in layered brittle-ductile systmes: implications for deformations of the continental lithosphere. Journal of Geophysical Research 100, 6281–94.Google Scholar
Dehls, J. F., Cruden, A. R. & Vigneresse, J. L. 1998. Fracture control of late-Archean pluton emplacement in the northern Slave Province, Canada. Journal of Structural Geology 20, 1145–54.Google Scholar
Dixon, J. M. & Simpson, D. G. 1987. Centrifuge modelling of laccolithic intrusion. Journal of Structural Geology 9, 87–103.Google Scholar
Grout, F. F. 1945. Scale models of structures related to batholiths. American Journal of Science 243, 260–84.Google Scholar
Guineberteau, B., Bouchez, J.-L. & Vigneresse, J.-L. 1987. The Mortagne granite pluton (France) emplaced by pull-apart along a shear zone: Structural and gravimetric arguments and regional implication. Geological Society of America Bulletin 99, 763–70.Google Scholar
Hogan, J. P., Price, J. D. & Gilbert, M. C. 1998. Magma traps and driving pressure—consequences for pluton shape and emplacement in an extensional regime. Journal of Structural Geology 20, 1155–68.Google Scholar
Horsfield, W. T. 1977. An experimental approach to basementcontrolled faulting. Geologie en Mijnbouw 56, 363–70.Google Scholar
Hubbert, M. K. 1937. Theory of scale models as applied to the study of geologic structures. Bulletin of the Geological Society of America 48, 1459–20.Google Scholar
Hutton, D. H. W. 1988. Granite emplacement mechanisms and tectonic controls: inferences from deformation studies. Transactions of the Royal Society of Edinburgh: Earth Sciences 79, 245–55.Google Scholar
Johnson, A. M. & Pollard, D. D. 1973. Mechanics of growth of some laccolithic intrusions in the Henry Mountains, Utah, I: field observations, Gilbert's model, physical properties and flow of the magma. Tectonophysics 18, 261–309.Google Scholar
Krantz, R. W. 1991. Measurements of friction coefficients and cohesion for faulting and fault reactivation in laboratory models using sand and sand mixtures. Tectonophysics 188, 203–7.Google Scholar
Paterson, S. R., Fowler, T. K. Jr. & Miller, R. B. 1996. Pluton emplacement in arcs: a crustal-scale exchange process. Transactions of the Royal Society of Edinburgh: Earth Sciences 87, 115–123.Google Scholar
Pavlis, T. L. 1996. Fabric development in syn-tectonic intrusive sheets as a consequence of melt-dominated flow and thermal softening of the crust. Tectonophysics 253, 1–31.Google Scholar
Petford, N. 1996. Dykes or diapirs? Transactions of the Royal Society of Edinburgh: Earth Sciences 87, 105–14.Google Scholar
Pitcher, W. S. & Bussell, M. A. 1977. Structural control of batholithic emplacement in Peru: a review. Journal of the Geological Society, London 133, 249–56.Google Scholar
Pollard, D. D. & Johnson, A. M. 1973. Mechanics of growth of some laccolithic intrusions in the Henry Mountains, Utah, II: bending and failure of overburden layers and sill formation. Tectonophysics 18, 311–54.Google Scholar
Ramberg, H. 1970. Model studies in relation to intrusion of plutonic bodies. In Newall, G. & Rast, N. (eds) Mechanism of igneous intrusion, 261–86. Liverpool: Gallery Press.Google Scholar
Ramberg, H. 1981. Gravity, Deformation and the Earth's Crust. London: Academic Press.Google Scholar
Robin, P.-Y. & Cruden, A. R. 1994. Strain and vorticity patterns in ideally ductile transpression zones. Journal of Structural Geologv 16, 447–66. Roman-Berdiel, T., Gapais, D. & Brun, J.-P. 1995. Analogue models of laccolith formation. Journal of Structural Geology 17, 1337–46. Roman-Berdiel, T., Gapais, D. & Brun, J.-P. 1997. Granite intrusion along strike-slip shear zones in experiment and nature. American Journal of Science 297, 651–78.Google Scholar
Sanford, A. R. 1959. Analytical and experimental study of simple geological structures. Bulletin of the Geological Society of America 70, 19–52.Google Scholar
Sawyer, E. W. 1994. Melt segregation in the continental crust. Geology 22, 1019–22.Google Scholar
Scaillet, B., Holtz, F. & Pichavant, M., 1997. Rheological properties of granitic magmas in their crystallization range. In Bouchez, J.-L., Hutton, D. H. W. & Stephens, W. E. (eds) Granite: from segregation of melt to emplacement fabrics, 11–29. Dordrecht: Kluwer Academic Publishers.Google Scholar
Tommasi, A., Vauchez, A., Fernandes, L. A. D. & Porcher, C. C. 1994. Magma-assisted strain localization in an orogen-parallel transcurrent shear zone of southern Brazil. Tectonics 13, 421–37.Google Scholar
Vendeville, B., Cobbold, P. R., Davy, P., Brun, J.-P. & Choukroune, P. 1987. Physical models of extensional tectonics at various scales. In Coward, M. P., Dewey, J. F. & Hancock, P. L. (eds) Continental extensional tectonics, 95–107. Geological Society Special Publication 28, 95–107.Google Scholar
Vigneresse, J.-L. 1988. Forme et volume des plutons granitiques. Bulletin de la Societe geologique de France 8, 897–906.Google Scholar
Vigneresse, J.-L. 1995. Control of granite emplacement by regional deformation. Tectonophysics 249, 173–86.Google Scholar
Yoshinobu, A. S. & Schmidt, K. L. 1999. Pluton emplacement during transpression in brittle crust: new views from analogue experiments: Comment. Geology 27, 670.Google Scholar