Nannofossils: the smoking gun for the Canarian hotspot |
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Authors: | Valentin R Troll Frances M Deegan Steffi Burchardt Kirsten Zaczek Juan‐Carlos Carracedo Fiona C Meade Vicente Soler Mario Cachao Jorge Ferreira Abigail K Barker |
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Institution: | 1. Uppsala University, Department of Earth Sciences, Centre for Experimental Mineralogy, Petrology and Geochemistry (CEMPEG), Uppsala, Sweden;2. University of Las Palmas de Gran Canaria, Department of Physics (GEOVOL), Las Palmas de Gran Canaria, Spain;3. Estacion Volcanologica de Canarias, IPNA‐CSIC, La Laguna, Tenerife, Spain;4. University of Lisbon, Faculty of Sciences, Instituto Dom Luiz (Geology), Portugal |
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Abstract: | The origin of volcanism in the Canary Islands has been a matter of controversy for several decades. Discussions have hinged on whether the Canaries owe their origin to seafloor fractures associated with the Atlas Mountain range or to an underlying plume or hotspot of superheated mantle material. However, the debate has recently come to a conclusion following the discovery of nannofossils preserved in the products of the 2011–2012 submarine eruption at El Hierro, which tell us about the age and growth history of the western‐most island of the archipelago. Light coloured, pumice‐like ‘floating rocks’ were found on the sea surface during the first days of the eruption and have been shown to contain fragments of pre‐island sedimentary strata. These sedimentary rock fragments were picked up by ascending magma and transported to the surface during the eruption, and remarkably retained specimens of pre‐island Upper Cretaceous to Pliocene calcareous nannofossils (e.g. coccolithophores). These marine microorganisms are well known biostratigraphical markers and now provide crucial evidence that the westernmost and youngest island in the Canaries is underlain by the youngest sediment relative to the other islands in the archipelago. This finding supports an age progression for the onset of volcanism at the individual islands of the archipeligo. Importantly, as fracture‐related volcanism is known to produce non‐systematic age‐distributions within volcanic alignments, the now‐confirmed age progression corroberates to the relative motion of the African plate over an underlying mantle plume or hotspot as the cause for the present‐day Canary volcanism. |
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