Thermal history of the Earth and its petrological expression

Herzberg, Claude; Condie, Kent C.; Korenaga, Jun

doi:10.1016/j.epsl.2010.01.022

Cited by 933 publications

(788 citation statements)

References 124 publications

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Section: (F) Cycle Time Of the Mantlementioning

confidence: 96%

“…The equivalent heat flux per unit area was of the order of 0.1 W m −2 [49], modestly higher than the present global mantle heat flow of approximately 0.07 W m −2 . Herzberg et al [49] prefer a mantle thermal history where the internal temperature at the end of vigorous initial Hadean convection was 50-150 K hotter than present. The internal temperature then increased to a maximum of 150-250 K hotter than present at around 3 Ga. Globally averaged tectonic rates would have been slower than present ones during this Hadean and Archaean epoch.…”

Section: (F) Cycle Time Of the Mantlementioning

confidence: 96%

“…Furthermore, most of the mantle was probably already frozen on the adiabat of the slurry epoch. Only modest cooling (at most a few hundred kelvins) of the mantle on average is allowed between approximately 10 Myr after the Moon-forming impact and the approximately 3.8 Ga age in the Archaean for which petrologists are able to infer mantle temperatures by studying komatiite lavas [48,49]. The hottest Archaean komatiites were probably the product of mantle plumes, indicating that Archaean mantle temperatures were heterogeneous.…”

Section: (F) Cycle Time Of the Mantlementioning

confidence: 99%

“…The net effect would have been the reduction of the average temperature of the mantle towards that of foundered lid material. In this scenario, radioactivity then heated the Hadean mantle from this minimum state to a maximum in the mid-Archaean [49].…”

Section: (A) Shallow Geochemical Processesmentioning

confidence: 99%

“…[48,49]). Evidence of heterogeneous mantle temperatures is then provided by Archaean igneous rocks, but there are no relevant Hadean data [48][49][50].…”

Section: (C) Freezing Of Deep Mantlementioning

confidence: 99%

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Terrestrial aftermath of the Moon-forming impact

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Zahnle

Lupu

2014

Phil. Trans. R. Soc. A.

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Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO 2 , formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m −2 . The duration of this runaway greenhouse stage was limited to approximately 10 Myr by the internal energy and tidal heating, ending with a partially crystalline uppermost mantle and a solid deep mantle. At this point, the crust was able to cool efficiently and solidified at the surface. After the condensation of the water ocean, approximately 100 bar of CO 2 remained in the atmosphere, creating a solar-heated greenhouse, while the surface cooled to approximately 500 K. Almost all this CO 2 had to be sequestered by subduction into the mantle by 3.8 Ga, when the geological record indicates the presence of life and hence a habitable environment. The deep CO 2 sequestration into the mantle could be explained by a rapid subduction of the old oceanic crust, such that the top of the crust would remain cold and retain its CO 2 . Kinematically, these episodes would be required to have both fast subduction (and hence seafloor spreading) and old crust. Hadean oceanic crust that formed from hot mantle would have been thicker than modern crust, and therefore only old crust underlain by cool mantle lithosphere could subduct. Once subduction started, the basaltic crust would turn into dense eclogite, increasing the rate of subduction. The rapid subduction would stop when the young partially frozen crust from the rapidly spreading ridge entered the subduction zone.

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Section: (F) Cycle Time Of the Mantlementioning

confidence: 96%

Section: (F) Cycle Time Of the Mantlementioning

confidence: 96%

Section: (F) Cycle Time Of the Mantlementioning

confidence: 99%

Section: (A) Shallow Geochemical Processesmentioning

confidence: 99%

“…[48,49]). Evidence of heterogeneous mantle temperatures is then provided by Archaean igneous rocks, but there are no relevant Hadean data [48][49][50].…”

Section: (C) Freezing Of Deep Mantlementioning

confidence: 99%

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Terrestrial aftermath of the Moon-forming impact

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Zahnle

Lupu

2014

Phil. Trans. R. Soc. A.

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Implications of a long‐lived basal magma ocean in generating Earth's ancient magnetic field

Ziegler

Stegman

2013

Geochem Geophys Geosyst

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[1] Observations of Earth's magnetic field extending back to 3.45 billion years ago indicate that generation by a core dynamo must be sustained over most of Earth's history. However, recent estimates of thermal and electrical conductivity of liquid iron at core conditions from mineral physics experiments indicate that adiabatic heat flux is approximately 15 TW, nearly three times larger than previously thought, exacerbating difficulties for driving a core dynamo throughout Earth history by convective core cooling alone. Here, we explore the geomagnetic consequences of a basal magma ocean layer in the lowermost mantle, hypothesized to exist in the early Earth and perhaps surviving until well after the Archean. While the modern, solid lower mantle is an electromagnetic insulator, electrical conductivities of silicate melts are known to be higher, though as yet they are unconstrained for lowermost mantle conditions. We consider a range of possible electrical conductivities and find that for the highest electrical conductivities considered, a long-lived basal magma ocean could be a primary dynamo source region. This would suggest the proposed three magnetic eras observed in paleomagnetic data originate from distinct sources for dynamo generation: from 4.5 to 2.45 Ga within a basal magma ocean, from 2.25 to 0.4 Ga within a superadiabatically cooled liquid core, and from 0.4 Ga to present within a quasi-adiabatic core that includes a solidifying inner core.Components: 6,241 words, 3 figures.

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Physics of crustal fracturing and chert dike formation triggered by asteroid impact, ∼3.26 Ga, Barberton greenstone belt, South Africa

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Lowe

2014

Geochem. Geophys. Geosyst.

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Archean asteroid impacts, reflected in the presence of spherule beds in the 3.2-3.5 Ga Barberton greenstone belt (BGB), South Africa, generated extreme seismic waves. Spherule bed S2 provides a field example. It locally lies at the contact between the Onverwacht and Fig Tree Groups in the BGB, which formed as a result of the impact of asteroid (possibly 50 km diameter). Scaling calculations indicate that very strong seismic waves traveled several crater diameters from the impact site, where they widely damaged Onverwacht rocks over much of the BGB. Lithified sediments near the top of the Onverwacht Group failed with opening-mode fractures. The underlying volcanic sequence then failed with normal faults and opening-mode fractures. Surficial unlithified sediments liquefied and behaved as a fluid. These liquefied sediments and some impact-produced spherules-filled near-surface fractures, today represented by swarms of chert dikes. Strong impact-related tsunamis then swept the seafloor. P waves and Rayleigh waves from the impact greatly exceeded the amplitudes of typical earthquake waves. The duration of extreme shaking was also far longer, probably hundreds of seconds, than that from strong earthquakes. Dynamic strains of 10 23 occurred from the surface and downward throughout the lithosphere. Shaking weakened the Onverwacht volcanic edifice and the surface layers locally moved downhill from gravity accommodated by faults and open-mode fractures. Coast-parallel opening-mode fractures on the fore-arc coast of Chile, formed as a result of megathrust events, are the closest modern analogs. It is even conceivable that dynamic stresses throughout the lithosphere initiated subduction beneath the Onverwacht rocks.

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Thermal history of the Earth and its petrological expression

Cited by 933 publications

References 124 publications

Terrestrial aftermath of the Moon-forming impact

Terrestrial aftermath of the Moon-forming impact

Implications of a long‐lived basal magma ocean in generating Earth's ancient magnetic field

Physics of crustal fracturing and chert dike formation triggered by asteroid impact, ∼3.26 Ga, Barberton greenstone belt, South Africa

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