A thin elastic core can control large-scale patterns of lithosphere shortening |
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| Authors: | FO Marques YY Podladchikov |
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| Institution: | 1. Institute of Petrology and Structural Geology, Faculty of Science, Charles University, Albertov 6, 12843 Prague, Czech Republic;2. Institute of Geology and Paleontology, Faculty of Science, Charles University, Albertov 6, 12843 Prague, Czech Republic;1. Universidade de Lisboa, 1749-016 Lisboa, Portugal;2. Department of Earth Sciences, Carleton University, Ottawa, ON K1S 5B6, Canada;3. Jadavpur University, Kolkata, India;1. Department of Geology, Faculty of Sciences, University of Isfahan, P. O. Code: 81746-73441 Isfahan, Iran;2. Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Villav?gen 16, SE-752 36 Uppsala, Sweden |
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| Abstract: | Peak lithospheric strength should reside in the rocks that, under the applied stress, cannot either creep (due to low temperature) or break (due to high confining pressure). The greatest resistance comes from dry olivine/pyroxene-rich upper mantle/lowermost crust at Moho conditions (400–600 °C and > 1 GPa). We have conducted laboratory experiments to investigate the importance of the unbreakable core of the lithosphere in between its brittle and ductile parts and conclude that it can control the large-scale lithospheric deformation pattern under shortening. Regardless of the thickness of the unbreakable core, it acts as a restraining layer that is easily flexed but is unstretchable. This eliminates large scale brittle faulting or homogeneous thickening as available shortening modes and results in irregular wrinkling of the unbreakable layer. We discuss geodynamic implications of our laboratory experiments and advocate studies of large scale buckling of the lithosphere as a relevant shortening mode. |
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