New 40Ar/39Ar age and geochemical data from seamounts in the Canary and Madeira volcanic provinces: support for the mantle plume hypothesis.

Geldmacher, Jörg , Hoernle, Kaj , van den Bogaard, Paul, Duggen, Svend and Werner, Reinhard (2005) New 40Ar/39Ar age and geochemical data from seamounts in the Canary and Madeira volcanic provinces: support for the mantle plume hypothesis. Earth and Planetary Science Letters, 237 (1-2). pp. 85-101. DOI 10.1016/j.epsl.2005.04.037.

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The role of mantleplumes in the formation of intraplate volcanic islands and seamount chains is being increasingly questioned. Particular examples are the abundant and somewhat irregularly distributed island and seamount volcanoes off the coast of northwest Africa. New40Ar / 39Ar ages and Sr–Nd–Pb isotope geochemistry of volcanic rocks from seamounts northeast of the Madeira Islands (Seine and Unicorn) and northeast of the Canary Islands (Dacia and Anika), however, provide support for the plumehypothesis. The oldest ages of shield stage volcanism from Canary and Madeiravolcanic provinces confirm progressions of increasing age to the northeast. Average volcanicage progression of ∼1.2 cm/a is consistent with rotation of the African plate at an angular velocity of ∼0.20° ± 0.05 /Ma around a common Euler pole at approximately 56° N, 45° W computed for the period of 0–35 Ma. A Euler pole at 35° N, 45° W is calculated for the time interval of 35–64 Ma. The isotope geochemistry further confirms that the Madeira and Canary provinces are derived from different sources, consistent with distinct plumes having formed each volcanic group. Conventional hotspot models, however, cannot easily explain the up to 40 m.y. long volcanic history at single volcanic centers, long gaps in volcanic activity, and the irregular distribution of islands and seamounts in the Canary province. A possible explanation could involve interaction of the Canarymantleplume with small-scale upper mantle processes such as edge-driven convection. Juxtaposition of plume and non-plume volcanism could also account for observed inconsistencies of the classical hotspot concept in other volcanic areas.

Document Type: Article
Keywords: Canary and Madeira islands; East Atlantic volcanism; African plate motion; Hotspot; 40Ar/39Ar age dating; Isotope geochemistry; Volcanism
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2005.04.037
ISSN: 0012-821X
Date Deposited: 03 Dec 2008 16:50
Last Modified: 21 Dec 2016 09:03

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