Petrology-based modeling of mantle melt electrical conductivity and joint interpretation of electromagnetic and seismic results

A. Pommier, Edward Garnero

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The presence of melt in the Earth's interior depends on the thermal state, bulk chemistry, and dynamics. Therefore, the investigation of the physical and chemical properties of melt is a probe of the planet's structure, dynamics, and potentially evolution. Here we explore melt properties by interpreting geophysical data sets sensitive to the presence of melt (electromagnetic and seismic) with considerations of petrology and, in particular, peridotite partial melting. We present a petrology-based model of the electrical conductivity of fertile and depleted peridotites during partial melting. Seismic and magnetotelluric (MT) studies do not necessarily agree on melt fraction estimates, a possible explanation being the assumptions made about melt chemistry as part of MT data interpretation. Melt fraction estimates from electrical anomalies usually assume a basaltic melt phase, whereas petrological knowledge suggests that the first liquids produced have a different chemistry, and thus a different conductivity. Our results show that melts produced by low-degree peridotite melting (< 15 vol %) are up to 5 times more conductive than basaltic liquids. Such conductive melts significantly affect bulk rock conductivity. Application of our electrical model to magnetotelluric results suggests melt fractions that are in good agreement with seismic estimates. With the aim of a simultaneous interpretation of electrical and seismic data, we combine our electrical results with seismic velocity considerations in a joint model of partial melting. Field electrical and seismic anomalies can be explained by ∼1 vol % melt beneath Hawaii and ∼1-8 vol % melt beneath the Afar Ridge.

Original languageEnglish (US)
Pages (from-to)4001-4016
Number of pages16
JournalJournal of Geophysical Research: Solid Earth
Volume119
Issue number5
DOIs
StatePublished - 2014

Fingerprint

Petrology
petrology
Magnetotellurics
electrical conductivity
Earth mantle
Melting
melt
electromagnetism
mantle
electrical resistivity
modeling
melting
peridotite
chemistry
Liquids
Planets
Chemical properties
estimates
partial melting
anomalies

Keywords

  • electrical conductivity
  • electromagnetic
  • partial melt
  • peridotite
  • seismology

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

@article{4fbcf03eceda4abd849eef528fc7f502,
title = "Petrology-based modeling of mantle melt electrical conductivity and joint interpretation of electromagnetic and seismic results",
abstract = "The presence of melt in the Earth's interior depends on the thermal state, bulk chemistry, and dynamics. Therefore, the investigation of the physical and chemical properties of melt is a probe of the planet's structure, dynamics, and potentially evolution. Here we explore melt properties by interpreting geophysical data sets sensitive to the presence of melt (electromagnetic and seismic) with considerations of petrology and, in particular, peridotite partial melting. We present a petrology-based model of the electrical conductivity of fertile and depleted peridotites during partial melting. Seismic and magnetotelluric (MT) studies do not necessarily agree on melt fraction estimates, a possible explanation being the assumptions made about melt chemistry as part of MT data interpretation. Melt fraction estimates from electrical anomalies usually assume a basaltic melt phase, whereas petrological knowledge suggests that the first liquids produced have a different chemistry, and thus a different conductivity. Our results show that melts produced by low-degree peridotite melting (< 15 vol {\%}) are up to 5 times more conductive than basaltic liquids. Such conductive melts significantly affect bulk rock conductivity. Application of our electrical model to magnetotelluric results suggests melt fractions that are in good agreement with seismic estimates. With the aim of a simultaneous interpretation of electrical and seismic data, we combine our electrical results with seismic velocity considerations in a joint model of partial melting. Field electrical and seismic anomalies can be explained by ∼1 vol {\%} melt beneath Hawaii and ∼1-8 vol {\%} melt beneath the Afar Ridge.",
keywords = "electrical conductivity, electromagnetic, partial melt, peridotite, seismology",
author = "A. Pommier and Edward Garnero",
year = "2014",
doi = "10.1002/2013JB010449",
language = "English (US)",
volume = "119",
pages = "4001--4016",
journal = "Journal of Geophysical Research: Atmospheres",
issn = "2169-897X",
publisher = "Wiley-Blackwell",
number = "5",

}

TY - JOUR

T1 - Petrology-based modeling of mantle melt electrical conductivity and joint interpretation of electromagnetic and seismic results

AU - Pommier, A.

AU - Garnero, Edward

PY - 2014

Y1 - 2014

N2 - The presence of melt in the Earth's interior depends on the thermal state, bulk chemistry, and dynamics. Therefore, the investigation of the physical and chemical properties of melt is a probe of the planet's structure, dynamics, and potentially evolution. Here we explore melt properties by interpreting geophysical data sets sensitive to the presence of melt (electromagnetic and seismic) with considerations of petrology and, in particular, peridotite partial melting. We present a petrology-based model of the electrical conductivity of fertile and depleted peridotites during partial melting. Seismic and magnetotelluric (MT) studies do not necessarily agree on melt fraction estimates, a possible explanation being the assumptions made about melt chemistry as part of MT data interpretation. Melt fraction estimates from electrical anomalies usually assume a basaltic melt phase, whereas petrological knowledge suggests that the first liquids produced have a different chemistry, and thus a different conductivity. Our results show that melts produced by low-degree peridotite melting (< 15 vol %) are up to 5 times more conductive than basaltic liquids. Such conductive melts significantly affect bulk rock conductivity. Application of our electrical model to magnetotelluric results suggests melt fractions that are in good agreement with seismic estimates. With the aim of a simultaneous interpretation of electrical and seismic data, we combine our electrical results with seismic velocity considerations in a joint model of partial melting. Field electrical and seismic anomalies can be explained by ∼1 vol % melt beneath Hawaii and ∼1-8 vol % melt beneath the Afar Ridge.

AB - The presence of melt in the Earth's interior depends on the thermal state, bulk chemistry, and dynamics. Therefore, the investigation of the physical and chemical properties of melt is a probe of the planet's structure, dynamics, and potentially evolution. Here we explore melt properties by interpreting geophysical data sets sensitive to the presence of melt (electromagnetic and seismic) with considerations of petrology and, in particular, peridotite partial melting. We present a petrology-based model of the electrical conductivity of fertile and depleted peridotites during partial melting. Seismic and magnetotelluric (MT) studies do not necessarily agree on melt fraction estimates, a possible explanation being the assumptions made about melt chemistry as part of MT data interpretation. Melt fraction estimates from electrical anomalies usually assume a basaltic melt phase, whereas petrological knowledge suggests that the first liquids produced have a different chemistry, and thus a different conductivity. Our results show that melts produced by low-degree peridotite melting (< 15 vol %) are up to 5 times more conductive than basaltic liquids. Such conductive melts significantly affect bulk rock conductivity. Application of our electrical model to magnetotelluric results suggests melt fractions that are in good agreement with seismic estimates. With the aim of a simultaneous interpretation of electrical and seismic data, we combine our electrical results with seismic velocity considerations in a joint model of partial melting. Field electrical and seismic anomalies can be explained by ∼1 vol % melt beneath Hawaii and ∼1-8 vol % melt beneath the Afar Ridge.

KW - electrical conductivity

KW - electromagnetic

KW - partial melt

KW - peridotite

KW - seismology

UR - http://www.scopus.com/inward/record.url?scp=84902436378&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84902436378&partnerID=8YFLogxK

U2 - 10.1002/2013JB010449

DO - 10.1002/2013JB010449

M3 - Article

VL - 119

SP - 4001

EP - 4016

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

SN - 2169-897X

IS - 5

ER -