Interaction between mantle and crustal detachments: A nonlinear system controlling lithospheric extension

Rosenbaum, G, Regenauer-Lieb, K and Weinberg, RF (2010) Interaction between mantle and crustal detachments: A nonlinear system controlling lithospheric extension. Journal of Geophysical Research B: Solid Earth, 115 11: B11412-1-B11412-16. doi:10.1029/2009JB006696


Author Rosenbaum, G
Regenauer-Lieb, K
Weinberg, RF
Title Interaction between mantle and crustal detachments: A nonlinear system controlling lithospheric extension
Journal name Journal of Geophysical Research B: Solid Earth   Check publisher's open access policy
ISSN 0148-0227
1934-8843
1934-8592
2156-2202
Publication date 2010-11-01
Year available 2010
Sub-type Article (original research)
DOI 10.1029/2009JB006696
Open Access Status DOI
Volume 115
Issue 11
Start page B11412-1
End page B11412-16
Total pages 16
Place of publication Washington, DC, United States
Publisher American Geophysical Union
Language eng
Subject 1908 Geophysics
1910 Oceanography
1107 Forestry
1104 Aquatic Science
2303 Ecology
3104 Condensed Matter Physics
2312 Water Science and Technology
1111 Soil Science
1906 Geochemistry and Petrology
1904 Earth-Surface Processes
1606 Physical and Theoretical Chemistry
2507 Polymers and Plastics
1902 Atmospheric Science
1901 Earth and Planetary Sciences (miscellaneous)
1912 Space and Planetary Science
2505 Materials Chemistry
1911 Palaeontology
Abstract We use numerical modeling to investigate the development of crustal and mantle detachments during lithospheric extension. Our models simulate a wide range of extensional systems with varying values of crustal thickness and heat flow, showing how strain localization in the mantle interacts with localization in the upper crust and controls the evolution of extensional systems. Model results reveal a richness of structures and deformation styles as a response to a self-organized mechanism that minimizes the internal stored energy of the system by localizing deformation. Crustal detachments, here referred as low-angle normal decoupling horizons, are well developed during extension of overthickened (60 km) continental crust, even when the initial heat flow is relatively low (50 mW m (2)). In contrast, localized mantle deformation is most pronounced when the extended lithosphere has a normal crustal thickness (30-40 km) and an intermediate heat flow (60-70 mW m(-2)). Results show a nonlinear response to subtle changes in crustal thickness or heat flow, characterized by abrupt and sometimes unexpected switches in extension modes (e. g., from diffuse extensional deformation to effective lithospheric-scale rupturing) or from mantle-to crust-dominated strain localization. We interpret this nonlinearity to result from the interference of doming wavelengths in the presence of multiple necking instabilities. Disharmonic crust and mantle doming wavelengths results in efficient communication between shear zones at different lithospheric levels, leading to rupturing of the whole lithosphere. In contrast, harmonic crust and mantle doming inhibits interaction of shear zones across the lithosphere and results in a prolonged history of extension prior to continental breakup.
Formatted abstract
We use numerical modeling to investigate the development of crustal and mantle detachments during lithospheric extension. Our models simulate a wide range of extensional systems with varying values of crustal thickness and heat flow, showing how strain localization in the mantle interacts with localization in the upper crust and controls the evolution of extensional systems. Model results reveal a richness of structures and deformation styles as a response to a self-organized mechanism that minimizes the internal stored energy of the system by localizing deformation. Crustal detachments, here referred as low-angle normal decoupling horizons, are well developed during extension of overthickened (60 km) continental crust, even when the initial heat flow is relatively low (50 mW m-2). In contrast, localized mantle deformation is most pronounced when the extended lithosphere has a normal crustal thickness (30-40 km) and an intermediate heat flow (60-70 mW m-2). Results show a nonlinear response to subtle changes in crustal thickness or heat flow, characterized by abrupt and sometimes unexpected switches in extension modes (e.g., from diffuse extensional deformation to effective lithospheric-scale rupturing) or from mantle- to crust-dominated strain localization. We interpret this nonlinearity to result from the interference of doming wavelengths in the presence of multiple necking instabilities. Disharmonic crust and mantle doming wavelengths results in efficient communication between shear zones at different lithospheric levels, leading to rupturing of the whole lithosphere. In contrast, harmonic crust and mantle doming inhibits interaction of shear zones across the lithosphere and results in a prolonged history of extension prior to continental breakup. © 2010 by the American Geophysical Union.
Keyword Metamorphic core complexes
Mid-atlantic ridge
Continental lithosphere
Rock mechanics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article # B11412

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
Official 2011 Collection
 
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Created: Sun, 19 Dec 2010, 10:10:03 EST