In geodynamics lower crustal flow is the mainly lateral movement of material within the lower part of the continental crust by a ductile flow mechanism. It is thought to be an important process during both continental collision and continental break-up.[1]
Rheology
editThe tendency of the lower crust to flow is controlled by its rheology. Ductile flow in the lower crust is assumed to be controlled by the deformation of quartz and/or plagioclase feldspar as its composition is thought to be granodioritic to dioritic. With normal thickness continental crust and a normal geothermal gradient, the lower crust, below the brittle–ductile transition zone, exhibits ductile flow behaviour under geological strain rates. Factors that can vary this behaviour include: water content, thickness, heat flow and strain-rate.
Collisional belts
editIn some areas of continental collision, the lower part of the thickened crust that results is interpreted to flow laterally, such as in the Tibetan plateau,[2] and the Altiplano in the Bolivian Andes.[3]
References
edit- ^ Brune, S.; Heine, C.; Pérez-Gussinyé, M.; Sobolev, S.V. (2014). "Rift migration explains continental margin asymmetry and crustal hyper-extension". Nature Communications. 5: 4014. Bibcode:2014NatCo...5.4014B. doi:10.1038/ncomms5014. PMC 4059923. PMID 24905463.
- ^ Chen, L.; Capitanio, F.A.; Liu, L.; Gerya, T.V. (2017). "Crustal rheology controls on the Tibetan plateau formation during India-Asia convergence". Nature Communications. 8: 15992. Bibcode:2017NatCo...815992C. doi:10.1038/ncomms15992. PMC 5524925. PMID 28722008.
- ^ Husson, L.; Sempere, T. (2003). "Thickening the Altiplano crust by gravity-driven crustal channel flow". Geophysical Research Letters. 30 (5): 1243. Bibcode:2003GeoRL..30.1243H. doi:10.1029/2002GL016877.
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