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.
| Language | English |
|---|---|
| Title of host publication | Lithospheric discontinuities |
| Editors | Huaiyu Yuan, Barbara Romanowicz |
| Place of Publication | Hoboken, NJ |
| Publisher | John Wiley & Sons |
| Chapter | 5 |
| Pages | 89-109 |
| Number of pages | 21 |
| ISBN (Electronic) | 9781119249740, 9781119249726, 9781119249733 |
| ISBN (Print) | 9781119249719 |
| DOIs | |
| Publication status | Published - 2019 |
Publication series
| Name | Geophysical Monograph |
|---|---|
| Publisher | John Wiley & Sons |
| Volume | 239 |
Fingerprint
Keywords
- Conductivity
- Craton
- Enrichment
- Fault
- Graphite
- Hydrogen
Cite this
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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 proceeding › Chapter › Research › peer-review
TY - CHAP
T1 - Electrical discontinuities in the continental lithosphere imaged with magnetotellurics
AU - Selway, Kate
PY - 2019
Y1 - 2019
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.
AB - 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.
KW - Conductivity
KW - Craton
KW - Enrichment
KW - Fault
KW - Graphite
KW - Hydrogen
UR - http://www.scopus.com/inward/record.url?scp=85056520196&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/arc/FT150100541
U2 - 10.1002/9781119249740.ch5
DO - 10.1002/9781119249740.ch5
M3 - Chapter
SN - 9781119249719
T3 - Geophysical Monograph
SP - 89
EP - 109
BT - Lithospheric discontinuities
A2 - Yuan, Huaiyu
A2 - Romanowicz, Barbara
PB - John Wiley & Sons
CY - Hoboken, NJ
ER -