Evolution of a fold-thrust belt deforming a unit with pre-existing linear asperities: Insights from analog models |
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| Institution: | 1. University of Oxford, Oxford, UK;2. Saudi Aramco, Dhahran, Saudi Arabia;1. Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, SO14 3ZH, UK;2. Department of Earth Science, University of Bergen, P.O. Box 7800, 5020 Bergen, Norway;1. Instituto Dom Luiz, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal;2. Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal;3. School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia;4. Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands;5. Department of Earth Sciences, Durham University, Science Labs, Durham DH1 3LE, UK;6. IPMA (Portuguese Institute for the Sea and Atmosphere), Division of Marine Geology and Georesources, Portugal;1. Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz, Iran;2. Exploration Directorate of the National Iranian Oil Company (NIOC), Tehran, Iran;3. Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan, China;1. Laboratorio de Modelado Geológico, Instituto de Estudios Andinos “Don Pablo Groeber” (IDEAN), Departamento de Ciencias Geológicas, FCEN, Universidad de Buenos Aires, BsAs C1428EGA, Argentina;2. School of Ocean and Earth Science and Technology, University of Hawaii, 1680 East-West Rd., Honolulu, HI 96822, USA;3. Schoolof Earth and Space Exploration, Arizona State University, Tempe, AZ, USA;4. Department of Geosciences, University of Massachusetts, Amherst, MA 01002, USA;5. Geodetic Science, Ohio State University, Columbus, OH, USA |
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| Abstract: | Heterogeneity, whether geometric or rheologic, in crustal material undergoing compression affects the geometry of the structures produced. This study documents the thrust fault geometries produced when discrete linear asperities are introduced into an analog model, scaled to represent bulk upper crustal properties, and compressed. Varying obliquities of the asperities are used, relative to the imposed compression, and the resultant development of thrust fault traces and branch lines in map view is tracked. Once the model runs are completed, cross-sections are created and analyzed. The models show that asperities confined to the base layer promote the clustering of branch lines in the surface thrusts. Strong clustering in branch lines is also noted where several asperities are in close proximity or cross. Slight reverse-sense reactivation of asperities cut through the sedimentary sequence is noted in cross-section, where the asperity and the subsequent thrust belt interact. The model results are comparable to the situation in the Dinaric Alps, where pre-existing faults to the SW of the NE Adriatic Fault Zone contribute to the clustering of branch lines developed in the surface fold-thrust belt. These results can therefore be used to evaluate the evolution of other basement-involved fold-thrust belts worldwide. |
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| Keywords: | Analog model Fault reactivation Fold-thrust belt Pre-existing fault Dinaric Alps |
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