Title: The <sup>40</sup>Ar/<sup>39</sup>Ar age dating of the Madeira Archipelago and hotspot track (eastern North Atlantic)
Abstract:The 40 Ar/ 39 Ar ages for 35 volcanic rocks and 14 C ages for two charcoal samples from the Madeira Archipelago and Ampère Seamount (eastern North Atlantic) are presented. The volcanic evolution of Ma...The 40 Ar/ 39 Ar ages for 35 volcanic rocks and 14 C ages for two charcoal samples from the Madeira Archipelago and Ampère Seamount (eastern North Atlantic) are presented. The volcanic evolution of Madeira can be divided into a voluminous shield stage (>4.6–0.7 Ma) and a subsequent low‐volume posterosional stage (<0.7–0 Ma). Volcanism during the shield stage originated from a two‐armed rift system, composed of the E–W oriented Madeira rift arm and the N–S oriented Desertas rift arm. Average growth rates for the submarine (5500 km 3 /Ma) and subaerial (100–150 km 3 /Ma) shield stages on Madeira are among the lowest found for ocean island volcanoes. It is proposed that Madeira represents the present location of a >70 Myr old hotspot which formed Porto Santo Island (11.1–14.3 Ma), Seine, Ampère (31 Ma), Corral Patch and Ormond (65–67 Ma [ Féraud et al. , 1982, 1986]) Seamounts, and the Serra de Monchique (70–72 Ma [ McIntyre and Berger, 1982]) complex in southern Portugal. Age and spatial relationships result in a calculated absolute African plate motion above the hotspot of 1.2 cm/yr around a rotation pole located at 43°36′N/ 24°33′W.Read More