Electrical discontinuities in the continental lithosphere imaged with magnetotellurics

Research output: Chapter in Book/Report/Conference proceedingChapterResearchpeer-review

Abstract

Magnetotelluric (MT) models reveal the continental lithosphere to be extremely electrically complex. In this chapter, I have combined experimental conductivity data on typical lithospheric minerals with estimates of standard lithospheric compositions to produce forward models of the predicted electrical structures of hypothetical, "typical" lithospheres. These models show consistently high (> 105 ohm · m) resistivities in the upper crust, compositionally dependent lower crustal resistivities between 102 and 104 ohm · m, and lithospheric mantle resistivities that decrease with depth and lie between 105 and 102 ohm · m. Most models predict a resistivity discontinuity at the crust-mantle boundary but often this may not be resolved by MT data. A review of MT models from the continental lithosphere shows that many reveal electrical discontinuities that are not predicted by these models of standard lithospheres. In the upper crust, fluids and conductive minerals, such as graphite or sulfides, are likely causes of conductive anomalies. In the lower crust and upper mantle, amphibole may be an important additional cause of conductors. With increasing temperature, high hydrogen contents can also produce conductive anomalies in the mantle. MT models reveal many features in the continental lithosphere that are not predicted by seismic or geochemical models, including large-volume conductors in tectonically stable lithospheric mantle, lateral conductivity discontinuities extending for tens of kilometers, and narrow conductors that penetrate the crust and mantle. Serious efforts to understand these features in the context of their conductivity causes and tectonic settings will significantly advance our understanding of the composition and evolution of the continental lithosphere.

LanguageEnglish
Title of host publicationLithospheric discontinuities
EditorsHuaiyu Yuan, Barbara Romanowicz
Place of PublicationHoboken, NJ
PublisherJohn Wiley & Sons
Chapter5
Pages89-109
Number of pages21
ISBN (Electronic)9781119249740, 9781119249726, 9781119249733
ISBN (Print)9781119249719
DOIs
Publication statusPublished - 2019

Publication series

NameGeophysical Monograph
PublisherJohn Wiley & Sons
Volume239

Fingerprint

continental lithosphere
Minerals
discontinuity
Amphibole Asbestos
Graphite
Sulfides
electrical resistivity
Hydrogen
mantle
Temperature
conductivity
upper crust
lithosphere
minerals
anomaly
crust-mantle boundary
tectonics
mineral
sulfides
tectonic setting

Keywords

  • Conductivity
  • Craton
  • Enrichment
  • Fault
  • Graphite
  • Hydrogen

Cite this

Selway, K. (2019). Electrical discontinuities in the continental lithosphere imaged with magnetotellurics. In H. Yuan, & B. Romanowicz (Eds.), Lithospheric discontinuities (pp. 89-109). (Geophysical Monograph; Vol. 239). Hoboken, NJ: John Wiley & Sons. https://doi.org/10.1002/9781119249740.ch5
Selway, Kate. / Electrical discontinuities in the continental lithosphere imaged with magnetotellurics. Lithospheric discontinuities. editor / Huaiyu Yuan ; Barbara Romanowicz. Hoboken, NJ : John Wiley & Sons, 2019. pp. 89-109 (Geophysical Monograph).
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Selway, K 2019, Electrical discontinuities in the continental lithosphere imaged with magnetotellurics. in H Yuan & B Romanowicz (eds), Lithospheric discontinuities. Geophysical Monograph, vol. 239, John Wiley & Sons, Hoboken, NJ, pp. 89-109. https://doi.org/10.1002/9781119249740.ch5

Electrical discontinuities in the continental lithosphere imaged with magnetotellurics. / Selway, Kate.

Lithospheric discontinuities. ed. / Huaiyu Yuan; Barbara Romanowicz. Hoboken, NJ : John Wiley & Sons, 2019. p. 89-109 (Geophysical Monograph; Vol. 239).

Research output: Chapter in Book/Report/Conference proceedingChapterResearchpeer-review

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N2 - Magnetotelluric (MT) models reveal the continental lithosphere to be extremely electrically complex. In this chapter, I have combined experimental conductivity data on typical lithospheric minerals with estimates of standard lithospheric compositions to produce forward models of the predicted electrical structures of hypothetical, "typical" lithospheres. These models show consistently high (> 105 ohm · m) resistivities in the upper crust, compositionally dependent lower crustal resistivities between 102 and 104 ohm · m, and lithospheric mantle resistivities that decrease with depth and lie between 105 and 102 ohm · m. Most models predict a resistivity discontinuity at the crust-mantle boundary but often this may not be resolved by MT data. A review of MT models from the continental lithosphere shows that many reveal electrical discontinuities that are not predicted by these models of standard lithospheres. In the upper crust, fluids and conductive minerals, such as graphite or sulfides, are likely causes of conductive anomalies. In the lower crust and upper mantle, amphibole may be an important additional cause of conductors. With increasing temperature, high hydrogen contents can also produce conductive anomalies in the mantle. MT models reveal many features in the continental lithosphere that are not predicted by seismic or geochemical models, including large-volume conductors in tectonically stable lithospheric mantle, lateral conductivity discontinuities extending for tens of kilometers, and narrow conductors that penetrate the crust and mantle. Serious efforts to understand these features in the context of their conductivity causes and tectonic settings will significantly advance our understanding of the composition and evolution of the continental lithosphere.

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BT - Lithospheric discontinuities

A2 - Yuan, Huaiyu

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PB - John Wiley & Sons

CY - Hoboken, NJ

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Selway K. Electrical discontinuities in the continental lithosphere imaged with magnetotellurics. In Yuan H, Romanowicz B, editors, Lithospheric discontinuities. Hoboken, NJ: John Wiley & Sons. 2019. p. 89-109. (Geophysical Monograph). https://doi.org/10.1002/9781119249740.ch5