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Defining Continental Lithosphere as a Layer With Abundant Frozen-In Structures That Scatter Seismic Waves

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Published version
Peer-reviewed

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Article

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Abstract

jats:titleAbstract</jats:title>jats:pWe investigate the structure of the continental lithosphere by combining two approaches: a systematic survey of abrupt changes in seismic properties detected by jats:italicP</jats:italic>‐to‐jats:italicS</jats:italic> converted body waves and an integrated geophysical‐petrological inversion for temperature and density in the upper mantle. We refine the global thermo‐chemical model WINTERC‐G in eastern North America by including detailed regional information on the crust into petrological inversions and combine it with the upper mantle layering beneath eastern North America yielded by anisotropy‐aware receiver‐function analysis. Eastern North America's Archean, Proterozoic and Paleozoic lithospheres show an excellent agreement between the depth to the 1,300°C isotherm that bounds the lithosphere and the depth range where converted waves detect abrupt changes in seismic properties. Boundaries with these abrupt changes reside within the rigid mechanical lithosphere and are uncommon in the convecting mantle beneath it. The boundaries include both impedance increases and decreases with depth, as well as anisotropy changes, and must have developed over the course of the assembly and evolution of the lithosphere. In the asthenosphere below, such heterogeneities appear to have been largely mixed out by convection. The existence of abundant interfaces with diverse origin can account for the commonly observed scattered signals from within the continental lithosphere and presents an alternative to the end‐member concept of the mid‐lithospheric discontinuity as a ubiquitous feature with a uniform origin. Generally, we can define continental lithosphere as a region of conductive heat transport and steep geotherm that is characterized by pervasive internal layering of density, elastic moduli and texture.</jats:p>

Description

Funder: Comunidad Autonoma de Madrid

Keywords

Earth's interior: composition and state, lithosphere, tomography, North America

Journal Title

Journal of Geophysical Research: Solid Earth

Conference Name

Journal ISSN

2169-9313
2169-9356

Volume Title

128

Publisher

American Geophysical Union (AGU)
Sponsorship
National Science Foundation (1735912)
European Space Agency (project 3D Earth)
Science Foundation Ireland (13/CDA/2192, 16/IA/4598)
Atracción de Talento (2018‐T1/AMB/11493)
Spanish Ministry of Science and Innovation (PID2020‐114854GB‐C22)