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Dynamics of a chemically pulsing mantle plume

Dynamics of a chemically pulsing mantle plume
Dynamics of a chemically pulsing mantle plume
Upwelling plumes from the deep mantle have an impact on the Earth’s surface for tens to hundreds of millions of years. During the lifetime of a mantle plume, periodic fluctuations in its composition and temperature have the potential to generate changes in the nature and volume of surface volcanism. We constrain the spatial and temporal scale of compositional changes in a plume using high-resolution Pb isotopes, which identify chemical pulses emerging from the Canary Islands hotspot over the last ~15 million years (Myr). Surface volcanism spanning ~400 km along the island chain changes composition systematically and synchronously, representing a replenishment of the plume head by a distinct mantle flavour on timescales of 3-5 Myr. These low-frequency compositional changes are also recorded by individual volcanoes, and comprise a sequence of closely-spaced isotopic trajectories. Each trajectory is maintained for ~1 Myr and is preceded and followed by ~0.3 Myr transitions to magmas with distinct isotope ratios. Relatively sharp transitions between periods of sustained isotopic stability require discrete yet coherent heterogeneities rising at speeds of ~100-200 km Myr−1 and extending for ~150 km vertically in the conduit. The long-term synchronous changes require larger scale isotopic domains extending ~600 km vertically through in the plume stem. These observations demonstrate that plumes can chemically “pulse” over short and long-timescales reflecting the characteristics and recycling history of the deep mantle.
Canary Islands, Pb isotopes, Tenerife, geochemistry, magmatic evolution, mantle plume, temporal and spatial volcanism
0012-821X
1-14
Taylor, Rex N
094be7fd-ef61-4acd-a795-7daba2bc6183
Davila-Harris, Pablo
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Branney, Michael J.
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Farley, E.M. Ruth
d36101b8-3aae-42e8-9c0a-fccd7df81abf
Gernon, Thomas M.
658041a0-fdd1-4516-85f4-98895a39235e
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080
Taylor, Rex N
094be7fd-ef61-4acd-a795-7daba2bc6183
Davila-Harris, Pablo
091d8c6a-62f7-44b9-9b09-9a6f1f1411aa
Branney, Michael J.
6b83ec2e-b523-49ad-b47a-6e659c0ffd49
Farley, E.M. Ruth
d36101b8-3aae-42e8-9c0a-fccd7df81abf
Gernon, Thomas M.
658041a0-fdd1-4516-85f4-98895a39235e
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080

Taylor, Rex N, Davila-Harris, Pablo, Branney, Michael J., Farley, E.M. Ruth, Gernon, Thomas M. and Palmer, Martin R. (2020) Dynamics of a chemically pulsing mantle plume. Earth and Planetary Science Letters, 537, 1-14, [116182]. (doi:10.1016/j.epsl.2020.116182).

Record type: Article

Abstract

Upwelling plumes from the deep mantle have an impact on the Earth’s surface for tens to hundreds of millions of years. During the lifetime of a mantle plume, periodic fluctuations in its composition and temperature have the potential to generate changes in the nature and volume of surface volcanism. We constrain the spatial and temporal scale of compositional changes in a plume using high-resolution Pb isotopes, which identify chemical pulses emerging from the Canary Islands hotspot over the last ~15 million years (Myr). Surface volcanism spanning ~400 km along the island chain changes composition systematically and synchronously, representing a replenishment of the plume head by a distinct mantle flavour on timescales of 3-5 Myr. These low-frequency compositional changes are also recorded by individual volcanoes, and comprise a sequence of closely-spaced isotopic trajectories. Each trajectory is maintained for ~1 Myr and is preceded and followed by ~0.3 Myr transitions to magmas with distinct isotope ratios. Relatively sharp transitions between periods of sustained isotopic stability require discrete yet coherent heterogeneities rising at speeds of ~100-200 km Myr−1 and extending for ~150 km vertically in the conduit. The long-term synchronous changes require larger scale isotopic domains extending ~600 km vertically through in the plume stem. These observations demonstrate that plumes can chemically “pulse” over short and long-timescales reflecting the characteristics and recycling history of the deep mantle.

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More information

Accepted/In Press date: 24 February 2020
e-pub ahead of print date: 9 March 2020
Published date: 1 May 2020
Keywords: Canary Islands, Pb isotopes, Tenerife, geochemistry, magmatic evolution, mantle plume, temporal and spatial volcanism

Identifiers

Local EPrints ID: 438714
URI: http://eprints.soton.ac.uk/id/eprint/438714
ISSN: 0012-821X
PURE UUID: b940ec7a-93c3-42b9-a919-535607bad9ae
ORCID for Thomas M. Gernon: ORCID iD orcid.org/0000-0002-7717-2092

Catalogue record

Date deposited: 23 Mar 2020 17:30
Last modified: 26 Nov 2021 02:55

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Contributors

Author: Rex N Taylor
Author: Pablo Davila-Harris
Author: Michael J. Branney
Author: E.M. Ruth Farley

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