Field reconnaissance of the Anti-Atlas coastline, Morocco: Fluvial and marine evidence for Late Cenozoic uplift |
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| Authors: | Rob Westaway Ali Aït Hssaine Tuncer Demir Anthony Beck |
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| Institution: | aThe Open University, Abbots Hill, Gateshead NE8 3DF, UK;bDepartment of Geography, Ibn Zohr University, Agadir, Morocco;cDepartment of Geography, Harran University, 63300 Şanlıurfa, Turkey;dDepartment of Geography, Durham University, South Road, Durham DH1 3LE, UK |
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| Abstract: | The available evidence regarding the disposition and chronology of Pliocene–Pleistocene fluvial terraces, coastal rock flats, raised beaches and lacustrine sediments adjoining the Anti-Atlas coastline of Morocco has been reviewed and supplemented by additional information from our own field reconnaissance. It is thus suggested that the study region has experienced uplift by  130 m since the Mid-Pliocene climatic optimum ( 3.1 Ma), by 90 m since the latest Pliocene ( 2 Ma), and by 45 m since the Mid-Pleistocene Revolution ( 0.9 Ma). Each of these phases of uplift correlates with a phase of global climate change known independently, and it is thus inferred that the observed uplift is being driven by climate through mechanisms such as erosional isostasy and the associated induced lower-crustal flow. Numerical modelling of the observed uplift history indicates that the mobile lower-crustal layer in the study region is 9 km thick, with a temperature at its base of 500 °C. The base of this mobile layer is inferred to be at 24 km depth, the deepest crust consisting of a layer of mafic underplating that does not flow under ambient conditions. The principal landform in the study region, the coastal rock platform at 60 m a.s.l., thus formed during a succession of interglacial marine highstands in the late Early Pleistocene when uplift rates were low. Although control on the ages of young sediments and landforms is currently extremely limited, being dependent on regional correlation schemes rather than on absolute dating, the study region fits the pattern, emerging worldwide, that climate change is driving the systematic growth of topographic relief evident during the Late Cenozoic. |
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| Keywords: | Morocco Anti-Atlas Pliocene Pleistocene uplift fluvial terraces marine terraces |
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