A unified continental thickness from seismology and diamonds suggests a melt-defined plate
A unified continental thickness from seismology and diamonds suggests a melt-defined plate
Thick, rigid continents move over the weaker underlying mantle, although geophysical and geochemical constraints on the exact thickness and defining mechanism of the continental plates are widely discrepant. Xenoliths suggest a chemical continental lithosphere ~175 kilometers thick, whereas seismic tomography supports a much thicker root (>250 kilometers) and a gradual lithosphere-asthenosphere transition, consistent with a thermal definition. We modeled SS precursor waveforms from continental interiors and found a 7 to 9% velocity drop at depths of 130 to 190 kilometers. The discontinuity depth is well correlated with the origin depths of diamond-bearing xenoliths and corresponds to the transition from coarse to deformed xenoliths. At this depth, the xenolith-derived geotherm also intersects the carbonate-silicate solidus, suggesting that partial melt defines the plate boundaries beneath the continental interior.
lithosphere-asthenosphere boundary, continents, partial melt
580-583
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Tharimena, Saikiran, Rychert, Catherine and Harmon, Nicholas
(2017)
A unified continental thickness from seismology and diamonds suggests a melt-defined plate.
Science, 357 (6351), .
(doi:10.1126/science.aan0741).
Abstract
Thick, rigid continents move over the weaker underlying mantle, although geophysical and geochemical constraints on the exact thickness and defining mechanism of the continental plates are widely discrepant. Xenoliths suggest a chemical continental lithosphere ~175 kilometers thick, whereas seismic tomography supports a much thicker root (>250 kilometers) and a gradual lithosphere-asthenosphere transition, consistent with a thermal definition. We modeled SS precursor waveforms from continental interiors and found a 7 to 9% velocity drop at depths of 130 to 190 kilometers. The discontinuity depth is well correlated with the origin depths of diamond-bearing xenoliths and corresponds to the transition from coarse to deformed xenoliths. At this depth, the xenolith-derived geotherm also intersects the carbonate-silicate solidus, suggesting that partial melt defines the plate boundaries beneath the continental interior.
Text
Tharimena_et_al_2017_Science(accepted)
- Accepted Manuscript
More information
Accepted/In Press date: 21 June 2017
e-pub ahead of print date: 10 August 2017
Keywords:
lithosphere-asthenosphere boundary, continents, partial melt
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Local EPrints ID: 413029
URI: http://eprints.soton.ac.uk/id/eprint/413029
ISSN: 0036-8075
PURE UUID: 1c6d1911-a360-404d-855c-2cb8e017c183
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Date deposited: 14 Aug 2017 16:30
Last modified: 16 Mar 2024 04:29
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