The Quaternary plant fossil record from the volcanic Azores Archipelago (Portugal, North Atlantic Ocean): a review

Abstract

Plant fossils are known from the Azores Islands, yet poorly studied. We present a comprehensive bibliographical review for the archipelago. A first pre-scientific reference dates from late fifteenth century, while the first scientific description was reported in 1821, accounting for trunks in pyroclastic units and silicified plants within hydrothermal deposits. Throughout the second-half of the nineteenth century and the first-half of the twentieth century, prospection by naturalists and geological mapping work, led to the discovery and description of plant fossils in most islands. From the 1970s onwards, the taxonomic interest ceased, and plant fossils were used mainly for ¹⁴C dating. Recently, sediment cores from lakes and peatlands were used for palaeoecological reconstructions and to measure anthropogenic impacts. Generally, plant fossils are younger than 50 ka, although older fossils may exist. Azorean plant fossils include somatofossils of leaves, stems, logs and seeds preserved as impressions, compressions, adpressions, permineralizations, lava tree casts and mummifications. The taphonomy of macrofloral elements is usually related to explosive volcanic activity, while palynological record is associated with lake sediments and peat bogs. The persistence in palaeobotanical and palaeopalynological studies will decisively contribute to disentangle the paleodiversity, palaeoecology, and add crucial information on insular plant phylogeny and biogeography.

Keywords:

• Macaronesia
• Azores Islands
• history of palaeontology
• plant fossils
• taphonomy
• palaeoecology

Acknowledgements

We would like to thank Fernando Pereira, for allowing the access to the fossil collections of the Volcano-speleological Museum, Manuel Steinbauer for field assistance in Terceira, Adriano Pimentel for indicating key outcrops in Faial, Juanma Rubiales for support with charcoal analysis and to Carlos Marques da Silva for constructive comments and discussion that enriched an early draft of this paper. We also want to express our gratitude to the three anonymous reviewers and their invaluable comments that improved this manuscript. CAG-M would like to acknowledge financial support from ARDITI – Regional Agency for the Development of Research, Technology and Innovation, project M1420- 09-5369-FSE-000001- PhD grant and JM to FCT-project UID/GEO/50019/2013-Instituto Dom Luiz.