Gravitational potential stresses and stress field of passive continental margins: Insights from the south-Norway shelf |
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| Authors: | Christophe Pascal Sierd APL Cloetingh |
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| Institution: | 1. Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany;2. Australian School of Petroleum, The University of Adelaide, SA 5005, Australia;3. Institute of Crustal Dynamics, China Earthquake Administration, 100085 Beijing, China;4. Geophysical Institute, Karlsruhe Institute of Technology KIT, Hertzstr. 16, 76187 Karlsruhe, Germany;5. Landesforschungszentrum Geothermie, Karlsruhe Institute of Technology KIT, Adenauerring 20b, 76131 Karlsruhe, Germany;6. Geothermal Engineering GmbH, Baischstr. 8, 76133 Karlsruhe, Germany;7. Institute of Applied Geosciences, Technical University Darmstadt, Schnittspahnstr. 9, 64287 Darmstadt, Germany;8. Institute of Earth and Environmental Science, Potsdam University, Karl-Liebknechtstr. 24-25, 14476 Potsdam, Germany;9. Department of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305, USA;1. University of Lisbon, Lisbon, Portugal;2. Swiss Federal Institute of Technology (ETH-Zürich), Zurich, Switzerland;3. University of São Paulo, São Paulo, Brazil;4. Federal University of Rio Grande do Norte, Natal, Brazil;1. Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia;2. V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia;3. Institute of Geology and Geophysics, Chinese Academy of Sciences, 19, Beitucheng West Road, Beijing, 100029, China |
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| Abstract: | It is commonly assumed that the stress state at passive margins is mainly dominated by ridge push and that other stress sources have only a limited temporal and/or spatial influence. We show, by means of numerical modelling, that observed variations in lithosphere structure and elevation from a margin towards continental interiors may also produce significant gravitational potential stresses competing with those induced by ridge push forces. We test this hypothesis on an actual case where abundant geological and geophysical datasets are available, the shelf of southern Norway and adjacent southern Norwegian mountains (or Southern Scandes). The modelling results are consistent with the main features of three key-observables: (1) undulations of the truncated geoid (reflecting variations in gravitational potential energy in the lithosphere), (2) significant stress rotations both offshore and onshore and (3) the seismicity pattern of southern Norway. The contribution of the Southern Scandes to the regional stress pattern appears to be far more significant than previously anticipated. In addition, the modelling provides a physical explanation for the enigmatic seismicity of southern Norway. Gravitational potential stresses arising from variations in the lithospheric structure between a passive margin and its continental borderlands, can exert a significant control on the dynamic evolution of the margin in concert with ridge push. |
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