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A global view of the lithosphere-asthenosphere boundary

A global view of the lithosphere-asthenosphere boundary
A global view of the lithosphere-asthenosphere boundary
The lithosphere-asthenosphere boundary divides the rigid lid from the weaker mantle and is fundamental in plate tectonics. However, its depth and defining mechanism are not well known. We analyzed 15 years of global seismic data using P-to-S (Ps) converted phases and imaged an interface that correlates with tectonic environment, varying from 95 ± 4 kilometers beneath Precambrian shields and platforms to 81 ± 2 kilometers beneath tectonically altered regions and 70 ± 4 kilometers at oceanic island stations. High-frequency Ps observations require a sharp discontinuity; therefore, this interface likely represents a boundary in composition, melting, or anisotropy, not temperature alone. It likely represents the lithosphere-asthenosphere boundary under oceans and tectonically altered regions, but it may constitute another boundary in cratonic regions where the lithosphere-asthenosphere boundary is thought to be much deeper.
0036-8075
495-498
Rychert, C.A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Shearer, P.M.
99ca21d2-2afb-423b-a6eb-e3747226afbe
Rychert, C.A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Shearer, P.M.
99ca21d2-2afb-423b-a6eb-e3747226afbe

Rychert, C.A. and Shearer, P.M. (2009) A global view of the lithosphere-asthenosphere boundary. Science, 324 (5926), 495-498. (doi:10.1126/science.1169754).

Record type: Article

Abstract

The lithosphere-asthenosphere boundary divides the rigid lid from the weaker mantle and is fundamental in plate tectonics. However, its depth and defining mechanism are not well known. We analyzed 15 years of global seismic data using P-to-S (Ps) converted phases and imaged an interface that correlates with tectonic environment, varying from 95 ± 4 kilometers beneath Precambrian shields and platforms to 81 ± 2 kilometers beneath tectonically altered regions and 70 ± 4 kilometers at oceanic island stations. High-frequency Ps observations require a sharp discontinuity; therefore, this interface likely represents a boundary in composition, melting, or anisotropy, not temperature alone. It likely represents the lithosphere-asthenosphere boundary under oceans and tectonically altered regions, but it may constitute another boundary in cratonic regions where the lithosphere-asthenosphere boundary is thought to be much deeper.

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Published date: 2009
Organisations: Geology & Geophysics

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Local EPrints ID: 340049
URI: http://eprints.soton.ac.uk/id/eprint/340049
ISSN: 0036-8075
PURE UUID: 2511fae3-cc4b-4370-b860-34019a2596d5

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Date deposited: 08 Jun 2012 08:12
Last modified: 14 Mar 2024 11:18

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Contributors

Author: C.A. Rychert
Author: P.M. Shearer

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