Effects of continents on Earth cooling: Thermal blanketing and depletion in radioactive elements

Grigné, Cécile; Labrosse, S.

doi:10.1029/2000gl012475

Cited by 65 publications

(53 citation statements)

References 13 publications

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“…It is well known that thick continental lithosphere has a thermal blanketing effect on the mantle below which result in higher mantle temperatures (e.g. Guillou and Jaupart, 1995;Grigne and Labrosse, 2001) if the rate of heat generation is greater than the rate of heat loss. More generally, beneath large continents the mode of convection locally behaves more like stagnant-lid convection, rather than plate tectonics.…”

Section: Discussionmentioning

confidence: 99%

Seismic anisotropy, mantle fabric, and the magmatic evolution of Precambrian southern Africa

Silver

2004

South African Journal of Geology

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The observed seismic anisotropy of the southern African mantle from both shear-wave splitting and surface wave observations provides important constraints on modes of mantle deformation beneath this ancient continent. We find that the mantle anisotropy beneath southern Africa is dominated by deformational events in Archean times occurring within the lithosphere, rather than present-day processes in the sublithospheric mantle. Consequently, the distribution and magnitude of anisotropy provide valuable data to constrain the mantle's role in the tectonic evolution of this region.

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Section: Discussionmentioning

confidence: 99%

Seismic anisotropy, mantle fabric, and the magmatic evolution of Precambrian southern Africa

Silver

2004

South African Journal of Geology

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“…Even the present value is poorly known. Ideally, it would be desirable to couple a model such as presented here to one for heat transfer across the mantle, either parameterized (eg Stevenson et al, 1983;Mollett, 1984;Grigné and Labrosse, 2001;Nimmo et al, 2004) or fully dynamical (eg. Nakagawa and Tackley, 2010).…”

Section: Thermal Evolution Modelsmentioning

confidence: 99%

Thermal evolution of the core with a high thermal conductivity

Labrosse

2015

Physics of the Earth and Planetary Interiors

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The rate at which heat is extracted across the core mantle boundary (CMB) is constrained by the requirement of dynamo action in the core. This constraint can be computed explicitly using the entropy balance of the core and depends on the thermal conductivity, whose value has been revised upwardly. A high order model (fourth degree polynomial of the radial position) for the core structure is derived and the implications for the core cooling rate and thermal evolution obtained, using the recent values of the thermal conductivity. For a thermal conductivity increasing with depth as proposed by some of these recent studies, a CMB heat flow equal to the isentropic value (13.25TW at present) leads to a 700 km thick layer at the top of the core where a downward convective heat flow is necessary to maintain an isentropic and well mixed average state. Considering a CMB heat flow larger than the well mixed isentropic value leads to an inner core less than 700 Myr old and the thermal evolution of the core is largely constrained by the conditions for dynamo action without an inner core. Analytical calculations for that period show that a CMB temperature larger than 7000 K must have prevailed 4.5 Gyr ago if the geodynamo has been driven by thermal convection for that whole time. This raises questions regarding the onset of the geodynamo and its continuous operation for the last 3.5 Gyr. Implications regarding the evolution of a basal magma ocean are also considered.

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“…Contrary to oceanic lithosphere, continental lithosphere is not directly subducted by mantle downwellings and behaves as a floating body of finite thermal conductivity overlying a convective system (Elder, 1967;Whitehead, 1976;Gurnis, 1988;Lenardic and Kaula, 1995;Jaupart et al, 1998;Grigné and Labrosse, 2001;Trubitsyn et al, 2006). Even if atmospheric temperature can be considered as a fixed temperature condition at the top of continents, it does not apply to their bottom parts (i.e., at the subcontinental lithosphere-asthenosphere boundary) since heat production within continents create temperature differences at depths.…”

Section: Mantle Convection and Heat Loss Beneath The Lithospherementioning

confidence: 99%

Reservoir Definition

Ledru¹,

Frottier

2010

Geothermal Energy Systems

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Effects of continents on Earth cooling: Thermal blanketing and depletion in radioactive elements

Abstract: Abstractfor present time, continental growth must begin at least 3 Gy ago and steady-state for continental area must be reached for at least 1.5 Gy in our cooling model.

Cited by 65 publications

References 13 publications

Seismic anisotropy, mantle fabric, and the magmatic evolution of Precambrian southern Africa

Seismic anisotropy, mantle fabric, and the magmatic evolution of Precambrian southern Africa

Thermal evolution of the core with a high thermal conductivity

Reservoir Definition

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