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Cartwright-Taylor A, Mangriotis MD, Main IG, Butler IB, Fusseis F, Ling M, Andò E, Curtis A, Bell AF, Crippen A, Rizzo RE, Marti S, Leung DDV, Magdysyuk OV. Seismic events miss important kinematically governed grain scale mechanisms during shear failure of porous rock. Nat Commun 2022; 13:6169. [PMID: 36257960 PMCID: PMC9579157 DOI: 10.1038/s41467-022-33855-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
Catastrophic failure in brittle, porous materials initiates when smaller-scale fractures localise along an emergent fault zone in a transition from stable crack growth to dynamic rupture. Due to the rapid nature of this critical transition, the precise micro-mechanisms involved are poorly understood and difficult to image directly. Here, we observe these micro-mechanisms directly by controlling the microcracking rate to slow down the transition in a unique rock deformation experiment that combines acoustic monitoring (sound) with contemporaneous in-situ x-ray imaging (vision) of the microstructure. We find seismic amplitude is not always correlated with local imaged strain; large local strain often occurs with small acoustic emissions, and vice versa. Local strain is predominantly aseismic, explained in part by grain/crack rotation along an emergent shear zone, and the shear fracture energy calculated from local dilation and shear strain on the fault is half of that inferred from the bulk deformation.
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Affiliation(s)
| | | | - Ian G Main
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Ian B Butler
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Florian Fusseis
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Martin Ling
- Independent Electronics Developer, Edinburgh Hacklab, Edinburgh, UK
| | - Edward Andò
- EPFL Center for Imaging, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andrew Curtis
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Andrew F Bell
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Alyssa Crippen
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Roberto E Rizzo
- School of GeoSciences, University of Edinburgh, Edinburgh, UK.,Department of Earth Sciences, University of Florence, Via La Pira 4, 50121, Florence, Italy
| | - Sina Marti
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Derek D V Leung
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Oxana V Magdysyuk
- Beamline I12-JEEP, Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK
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van der Merwe PDW, Cotterill FPD, Kandziora M, Watters BR, Nagy B, Genade T, Flügel TJ, Svendsen DS, Bellstedt DU. Genomic fingerprints of palaeogeographic history: The tempo and mode of rift tectonics across tropical Africa has shaped the diversification of the killifish genus Nothobranchius (Teleostei: Cyprinodontiformes). Mol Phylogenet Evol 2020; 158:106988. [PMID: 33059071 DOI: 10.1016/j.ympev.2020.106988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 09/16/2020] [Accepted: 10/07/2020] [Indexed: 01/04/2023]
Abstract
This paper reports a phylogeny of the African killifishes (Genus Nothobranchius, Order Cyprinodontiformes) informed by five genetic markers (three nuclear, two mitochondrial) of 80 taxa (seven undescribed and 73 of the 92 recognized species). These short-lived annual fishes occupy seasonally wet habitats in central and eastern Africa, and their distribution coincides largely with the East African Rift System (EARS). The fossil dates of sister clades used to constrain a chronometric tree of all sampled Nothobranchius recovered the origin of the genus at ~13.27 Mya. It was followed by the radiations of six principal clades through the Neogene. An ancestral area estimation tested competing biogeographical hypotheses to constrain the ancestral origin of the genus to the Nilo-Sudan Ecoregion, which seeded a mid-Miocene dispersal event into the Coastal ecoregion, followed closely (~10 Mya) by dispersals southward across the Mozambique coastal plain into the Limpopo Ecoregion. Extending westwards across the Tanzanian plateau, a pulse of radiations through the Pliocene were associated with dispersals and fragmentation of wetlands across the Kalahari and Uganda Ecoregions. We interpret this congruence of drainage rearrangements with dispersals and cladogenic events of Nothobranchius to reflect congruent responses to recurrent uplift and rifting. The coevolution of these freshwater fishes and wetlands is attributed to ultimate control by tectonics, as the EARS extended southwards during the Neogene. Geobiological consilience of the combined evidence supports a tectonic hypothesis for the evolution of Nothobranchius.
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Affiliation(s)
| | | | - Martha Kandziora
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
| | - Brian R Watters
- 6141 Parkwood Drive, Nanaimo, British Columbia V9T6A2, Canada
| | - Béla Nagy
- 30, Rue du Mont Ussy, 77300 Fontainebleau, France
| | - Tyrone Genade
- Biomedical Sciences, East Tennessee State University, USA
| | - Tyrel J Flügel
- Department of Geography and Environmental Studies, Stellenbosch University, South Africa
| | - David S Svendsen
- Department of Geography and Environmental Studies, Stellenbosch University, South Africa
| | - Dirk U Bellstedt
- Department of Biochemistry, Stellenbosch University, South Africa.
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