The Open UniversitySkip to content
 

Evidence for recycled Archaean oceanic mantle lithosphere in the Azores plume

Schaefer, Bruce F.; Turner, Simon; Parkinson, Ian; Rogers, Nick and Hawkesworth, Chris (2002). Evidence for recycled Archaean oceanic mantle lithosphere in the Azores plume. Nature, 420(6913) pp. 304–307.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1038/nature01172
Google Scholar: Look up in Google Scholar

Abstract

The compositional differences between mid-ocean-ridge and ocean-island basalts place important constraints on the form of mantle convection1, 2. Also, it is thought that the scale and nature of heterogeneities within plumes and the degree to which heterogeneous material endures within the mantle might be reflected in spatial variations of basalt composition observed at the Earth's surface. Here we report osmium isotope data on lavas from a transect across the Azores archipelago which vary in a symmetrical pattern across what is thought to be a mantle plume. Many of the lavas from the centre of the plume have lower 187Os/188Os ratios than most ocean-island basalts and some extend to subchondritic 187Os/188Os ratios—lower than any yet reported from ocean-island basalts. These low ratios require derivation from a depleted, harzburgitic mantle, consistent with the low-iron signature of the Azores plume. Rhenium-depletion model ages extend to 2.5 Gyr, and we infer that the osmium isotope signature is unlikely to be derived from Iberian subcontinental lithospheric mantle. Instead, we interpret the osmium isotope signature as having a deep origin and infer that it may be recycled, Archaean oceanic mantle lithosphere that has delaminated from its overlying oceanic crust. If correct, our data provide evidence for deep mantle subduction and storage of oceanic mantle lithosphere during the Archaean era.

Item Type: Journal Article
ISSN: 1476-4687
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 4967
Depositing User: Nick Rogers
Date Deposited: 17 Jul 2006
Last Modified: 02 Dec 2010 19:52
URI: http://oro.open.ac.uk/id/eprint/4967
Share this page:

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk