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Comment
. 2015 Nov 24;112(47):14410-1.
doi: 10.1073/pnas.1519765112. Epub 2015 Nov 12.

Penciling in details of the Hadean

Christopher H House  1
Affiliations
Comment

Penciling in details of the Hadean

Christopher H House. Proc Natl Acad Sci U S A. .
No abstract available

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Conflict of interest statement

The author declares no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Summary of the few carbon isotopic (δ13C) and redox constraints we have for the Earth’s earliest carbon cycle. In the upper left is the newly reported carbon isotopic value for a graphite inclusion in a 4.1 Ga Hadean zircon (−24 ± 4‰). This remarkable graphite provides a new constraint on the global carbon cycle in the Hadean. Also shown are Precambrian diamonds (bimodal at −5‰ and −25‰) and Early Archean microbial biomass (scattered around −25%). The Hadean zircon hosting the graphite comes from a continental crust setting, shown as thick and dark brown. Typically, continental crust forms in magma chambers above a subducting slab of oceanic crust, shown here in black. Finally, various measures of redox suggest that the Earth’s present upper mantle is mildly reducing and has been such for >3.8 billion y. (Inset) Similar constrains for magmatic carbon found in lunar rocks (around −20‰) and Martian meteorites (around −20‰). Both the Moon and Mars appear to have highly reducing mantles. (Inset image adapted from ref. .)
See this image and copyright information in PMC

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References

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