Publication Date:
2016-01-10
Description:
The newly developed Al-in-olivine geothermometer was used to find the olivine-Cr-spinel crystallisation temperatures of a suite of picrites spanning the spatial and temporal extent of the North Atlantic Igneous province (NAIP), which is widely considered to be the result of a deep-seated mantle plume. Our data confirm that start-up plumes are associated with a pulse of anomalously hot mantle over a large spatial area before becoming focused into a narrow upwelling. We find that the thermal anomaly on both sides of the province at Baffin Island/West Greenland and the British Isles at ∼61 Ma across an area ∼2000 km in diameter was uniform, with Al-in-olivine temperatures up to ∼300°C above that of average mid-ocean ridge basalt (MORB) primitive magma. Furthermore, by combining our results with geochemical data and existing geophysical and bathymetric observations, we present compelling evidence for long-term (〉10 7 year) fluctuations in the temperature of the Iceland mantle plume. We show that the plume temperature fell from its initial high value during the start-up phase to a minimum at about 35 Ma, and that the mantle temperature beneath Iceland is currently increasing. This article is protected by copyright. All rights reserved.
Electronic ISSN:
1525-2027
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
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