Isotopic contrasts, chronology of elemental transfers and high-grade metamorphism: the Sri Lanka Highland granulites, and the Lewisian (Scotland) and Nuk (SW Greenland) gneisses

Liew, T. C.; Milisenda, Claudio C.; Hofmann, A. W.

doi:10.1007/bf01829366

Cited by 29 publications

(2 citation statements)

References 35 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The times indicated in Myrs are the two-stage model ages of core formation assuming the same values for bulk earth parameters given by Halliday (2004) and Wood and Halliday (2005). Data from Doe and Zartman (1979), Davies (1984), Zartman and Haines (1988), Allègre et al (1988), Allègre and Lewin (1989), Kwon et al (1989), Liew et al (1991), Galer and Goldstein (1991), Kramers and Tolstikhin (1997), Kamber and Collerson (1999), and Murphy et al (2003). (Full references in Halliday 2004.)…”

Section: Core Formation Accretion and The Early Earthmentioning

confidence: 96%

Emergence of a Habitable Planet

et al. 2007

View full text Add to dashboard Cite

We address the first several hundred million years of Earth's history. The Moonforming impact left Earth enveloped in a hot silicate atmosphere that cooled and condensed over ∼1,000 yrs. As it cooled the Earth degassed its volatiles into the atmosphere. It took another ∼2 Myrs for the magma ocean to freeze at the surface. The cooling rate was determined by atmospheric thermal blanketing. Tidal heating by the new Moon was a major energy source to the magma ocean. After the mantle solidified geothermal heat became climatologically insignificant, which allowed the steam atmosphere to condense, and left behind a ∼100 bar, ∼500 K CO 2 atmosphere. Thereafter cooling was governed by how quickly CO 2 was removed from the atmosphere. If subduction were efficient this could have K. Zahnle ( ) K. Zahnle et al.taken as little as 10 million years. In this case the faint young Sun suggests that a lifeless Earth should have been cold and its oceans white with ice. But if carbonate subduction were inefficient the CO 2 would have mostly stayed in the atmosphere, which would have kept the surface near ∼500 K for many tens of millions of years. Hydrous minerals are harder to subduct than carbonates and there is a good chance that the Hadean mantle was dry. Hadean heat flow was locally high enough to ensure that any ice cover would have been thin (<5 m) in places. Moreover hundreds or thousands of asteroid impacts would have been big enough to melt the ice triggering brief impact summers. We suggest that plate tectonics as it works now was inadequate to handle typical Hadean heat flows of 0.2-0.5 W/m 2 . In its place we hypothesize a convecting mantle capped by a ∼100 km deep basaltic mush that was relatively permeable to heat flow. Recycling and distillation of hydrous basalts produced granitic rocks very early, which is consistent with preserved >4 Ga detrital zircons. If carbonates in oceanic crust subducted as quickly as they formed, Earth could have been habitable as early as 10-20 Myrs after the Moon-forming impact.

show abstract

Section: Core Formation Accretion and The Early Earthmentioning

confidence: 96%

Emergence of a Habitable Planet

et al. 2007

View full text Add to dashboard Cite

show abstract

“…The times indicated in million years are the twostage model ages of core formation assuming the same values for bulk Earth parameters given in Halliday (2004) and Wood and Halliday (2005). Data from Doe and Zartman (1979), Davies (1984), Zartman and Haines (1988), Allè gre et al (1988), Allè gre and Lewin (1989), Kwon et al (1989), Liew et al (1991), Galer and Goldstein (1991), Kramers and Tolstikhin (1997), Kamber and Collerson (1999), and Murphy et al (2003). These Pb isotope estimates are all significantly longer than the 182 Hf-182 W estimate of 30 My (Kleine et al, 2002;Yin et al, 2002).…”

Section: The Age Of the Earthmentioning

confidence: 91%