Cooling of the Earth

A parameterized convection study of whole versus layered models

Allen K. McNamara, Peter E. Van Keken

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Compositionally layered mantle models have often been invoked in order to explain the geochemistry observed at the Earth's surface, specifically the discrepancy between ocean island basalt and mid-ocean ridge basalt compositions. One disadvantage of layered models is the reduction in cooling efficiency compared to whole-mantle convection as a direct result of the insulating nature of the thermal boundary layer that develops between the two convecting layers. This may pose a significant problem for layered models in which the bottom layer is enriched in heat-producing radioactive elements with respect to the top layer. One may expect that the bottom layer would become superheated over the lifetime of the Earth. We perform this study in order to test whether layered models are thermally feasible. We are interested in discovering whether it was possible, within Earth-like constraints, to produce a bottom layer temperature that remains below the solidus without simultaneously producing a top layer that is too cool. We use parameterized convection to explore a wide parameter range of input values for several layering configurations. We study both a whole mantle convection model and the recently proposed layered convection model, which places the boundary between the layers at 1600-km depth [Kellogg et al., 1999]. We use the present-day heat flow and mantle viscosity as primary constraints and use the resulting average temperature as a test for the feasibility of the models. Our results reveal that for whole mantle convection, a wide parameter range produces results that satisfy our constraints. This is in contrast to the layered convection model in which we find that the parameter range that satisfies constraints is significantly reduced or perhaps, nonexistent.

Original languageEnglish (US)
Article number1027
JournalGeochemistry, Geophysics, Geosystems
Volume1
Issue number11
DOIs
StatePublished - Nov 1 2000
Externally publishedYes

Fingerprint

convection
Earth (planet)
Cooling
cooling
Earth mantle
mantle convection
basalt
Radioactive Elements
mantle
thermal boundary layer
Geochemistry
mid-ocean ridges
solidus
Convection
ocean island basalt
Earth surface
geochemistry
mid-ocean ridge basalt
heat transmission
radioactive isotopes

Keywords

  • convection
  • layered convection
  • mantle
  • parameterized
  • temperature
  • thermal evolution

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Cooling of the Earth : A parameterized convection study of whole versus layered models. / McNamara, Allen K.; Van Keken, Peter E.

In: Geochemistry, Geophysics, Geosystems, Vol. 1, No. 11, 1027, 01.11.2000.

Research output: Contribution to journalArticle

@article{d050668226d64613a35d130ed452f519,
title = "Cooling of the Earth: A parameterized convection study of whole versus layered models",
abstract = "Compositionally layered mantle models have often been invoked in order to explain the geochemistry observed at the Earth's surface, specifically the discrepancy between ocean island basalt and mid-ocean ridge basalt compositions. One disadvantage of layered models is the reduction in cooling efficiency compared to whole-mantle convection as a direct result of the insulating nature of the thermal boundary layer that develops between the two convecting layers. This may pose a significant problem for layered models in which the bottom layer is enriched in heat-producing radioactive elements with respect to the top layer. One may expect that the bottom layer would become superheated over the lifetime of the Earth. We perform this study in order to test whether layered models are thermally feasible. We are interested in discovering whether it was possible, within Earth-like constraints, to produce a bottom layer temperature that remains below the solidus without simultaneously producing a top layer that is too cool. We use parameterized convection to explore a wide parameter range of input values for several layering configurations. We study both a whole mantle convection model and the recently proposed layered convection model, which places the boundary between the layers at 1600-km depth [Kellogg et al., 1999]. We use the present-day heat flow and mantle viscosity as primary constraints and use the resulting average temperature as a test for the feasibility of the models. Our results reveal that for whole mantle convection, a wide parameter range produces results that satisfy our constraints. This is in contrast to the layered convection model in which we find that the parameter range that satisfies constraints is significantly reduced or perhaps, nonexistent.",
keywords = "convection, layered convection, mantle, parameterized, temperature, thermal evolution",
author = "McNamara, {Allen K.} and {Van Keken}, {Peter E.}",
year = "2000",
month = "11",
day = "1",
doi = "10.1029/2000GC000045",
language = "English (US)",
volume = "1",
journal = "Geochemistry, Geophysics, Geosystems",
issn = "1525-2027",
publisher = "American Geophysical Union",
number = "11",

}

TY - JOUR

T1 - Cooling of the Earth

T2 - A parameterized convection study of whole versus layered models

AU - McNamara, Allen K.

AU - Van Keken, Peter E.

PY - 2000/11/1

Y1 - 2000/11/1

N2 - Compositionally layered mantle models have often been invoked in order to explain the geochemistry observed at the Earth's surface, specifically the discrepancy between ocean island basalt and mid-ocean ridge basalt compositions. One disadvantage of layered models is the reduction in cooling efficiency compared to whole-mantle convection as a direct result of the insulating nature of the thermal boundary layer that develops between the two convecting layers. This may pose a significant problem for layered models in which the bottom layer is enriched in heat-producing radioactive elements with respect to the top layer. One may expect that the bottom layer would become superheated over the lifetime of the Earth. We perform this study in order to test whether layered models are thermally feasible. We are interested in discovering whether it was possible, within Earth-like constraints, to produce a bottom layer temperature that remains below the solidus without simultaneously producing a top layer that is too cool. We use parameterized convection to explore a wide parameter range of input values for several layering configurations. We study both a whole mantle convection model and the recently proposed layered convection model, which places the boundary between the layers at 1600-km depth [Kellogg et al., 1999]. We use the present-day heat flow and mantle viscosity as primary constraints and use the resulting average temperature as a test for the feasibility of the models. Our results reveal that for whole mantle convection, a wide parameter range produces results that satisfy our constraints. This is in contrast to the layered convection model in which we find that the parameter range that satisfies constraints is significantly reduced or perhaps, nonexistent.

AB - Compositionally layered mantle models have often been invoked in order to explain the geochemistry observed at the Earth's surface, specifically the discrepancy between ocean island basalt and mid-ocean ridge basalt compositions. One disadvantage of layered models is the reduction in cooling efficiency compared to whole-mantle convection as a direct result of the insulating nature of the thermal boundary layer that develops between the two convecting layers. This may pose a significant problem for layered models in which the bottom layer is enriched in heat-producing radioactive elements with respect to the top layer. One may expect that the bottom layer would become superheated over the lifetime of the Earth. We perform this study in order to test whether layered models are thermally feasible. We are interested in discovering whether it was possible, within Earth-like constraints, to produce a bottom layer temperature that remains below the solidus without simultaneously producing a top layer that is too cool. We use parameterized convection to explore a wide parameter range of input values for several layering configurations. We study both a whole mantle convection model and the recently proposed layered convection model, which places the boundary between the layers at 1600-km depth [Kellogg et al., 1999]. We use the present-day heat flow and mantle viscosity as primary constraints and use the resulting average temperature as a test for the feasibility of the models. Our results reveal that for whole mantle convection, a wide parameter range produces results that satisfy our constraints. This is in contrast to the layered convection model in which we find that the parameter range that satisfies constraints is significantly reduced or perhaps, nonexistent.

KW - convection

KW - layered convection

KW - mantle

KW - parameterized

KW - temperature

KW - thermal evolution

UR - http://www.scopus.com/inward/record.url?scp=0011262668&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0011262668&partnerID=8YFLogxK

U2 - 10.1029/2000GC000045

DO - 10.1029/2000GC000045

M3 - Article

VL - 1

JO - Geochemistry, Geophysics, Geosystems

JF - Geochemistry, Geophysics, Geosystems

SN - 1525-2027

IS - 11

M1 - 1027

ER -