The real 1%: Volatiles in planetary accretion and the rapid development of habitability

Lindy Elkins-Tanton DTM, Carnegie Institution

Elkins-Tanton What period of time are we talking about? 542 542 Ediacaran 630 First appearance of Ediacaran Fauna Major ice ages

Neo- First appearance of metazoans and glacial deposits

proterozoic 13 850 First appearance of δ C anomalies

1000

Environment stability; ‘Rodinian’ reducing deep oceans

1500 Mesoproterozoic

First appearance of sulphidic 1780 marine deposits

Proterozoic Supercontinent formation ‘Columbian’ (Columbia/Nuna) 2000 2060 End of LJE / Start of shungite deposition ‘Jatulian’/ Lomagundi-Jatuli isotopic excursion ‘Eukaryian’ 13 2250 First appearance of +ve δ C anomalies +/or breakout magmatism

Paleoproterozoic ‘Oxygenian’ Glaciations; rise in atmospheric O2 2420 First appearance of glacial deposits 2500 Deposition of BIF; waning continental growth 2630 First appearance of Hamersley BIF ‘Methanian’ Major crustal growth and recycling First appearance of continental flood 2780 13 basalts and/or +ve δ C kerogen values ‘Pongolan’ Basin deposition on stable continents 3000 3020 First appearance of terrestrial basins Archean Growth of stable continental nuclei; ‘Vaalbaran’ oldest macroscopic evidence for life

3490 First appearance of macroscopic 3500 fossils (stromatolites) First preserved sedimentary rocks, ‘Isuan’ with chemical traces of life

3810 Earth's oldest supracrustal rocks Oldest preserved pieces of continental crust

Paleoarchean ‘Acastan’ 4000 4030 Earth’s oldest rocks (Acasta Gneiss)

Rapid crust formation and recycling; continued heavy meteorite bombardement

‘Jack Hillsian’ or ‘Zirconian’ Earth’s oldest crustal material 4404 (detrital zircons) Accretion of giant Moon-forming 4500 ‘Chaotian’ impact event 4568 Formation of the solar system Van Kranendonk

Fig16.29 542 Ediacaran Ediacaran 630 First appearance of Ediacaran Fauna Major ice ages

Neo- Cryogenian First appearance of metazoans and glacial deposits

proterozoic 13 850 First appearance of δ C anomalies

1000

Environment stability; ‘Rodinian’ reducing deep oceans

1500 Mesoproterozoic

First appearance of sulphidic 1780 marine deposits

Proterozoic Supercontinent formation ‘Columbian’ (Columbia/Nuna) 2000 2060 End of LJE / Start of shungite deposition ‘Jatulian’/ Lomagundi-Jatuli isotopic excursion ‘Eukaryian’ 13 2250 First appearance of +ve δ C anomalies +/or breakout magmatism

Paleoproterozoic ‘Oxygenian’ Glaciations; rise in atmospheric O2 2420 First appearance of glacial deposits 2500 Siderian Deposition of BIF; waning continental growth 2630 First appearance of Hamersley BIF ‘Methanian’ Major crustal growth and recycling Neoarchean First appearance of continental flood 2780 13 basalts and/or +ve δ C kerogen values ‘Pongolan’ Basin deposition on stable continents 3000 3020 First appearance of terrestrial basins Archean Growth of stable continental nuclei; ‘Vaalbaran’ oldest macroscopic evidence for life Mesoarchean

3490 First appearance of macroscopic 3500 fossils (stromatolites) First preserved sedimentary rocks, ‘Isuan’ with chemical traces of life

3810 Earth's oldest supracrustal rocks Oldest preserved pieces of continental crust

Paleoarchean ‘Acastan’ 4000 4030 Earth’s oldest rocks (Acasta Gneiss)

Rapid crust formation and recycling; continued heavy meteorite bombardement

‘Jack Hillsian’ or ‘Zirconian’ Earth’s oldest crustal material 4404 (detrital zircons) Accretion of giant Moon-forming Hadean 4500 ‘Chaotian’ impact event 4568 FirstFormation solids inof thethe protoplanetarysolar system disk

Fig16.29

Van Kranendonk How do rocky planets obtain atmospheres?

1. Capture of nebular gases

2. Degassing from the interior

3. Later surface impacts What material are we working with? Lodders (2003) Data from Jarosewich (1990) Data from Jarosewich (1990) What processes make planets? Elkins-Tanton (2012) Ann.Rev. 1693: Leibniz suggests in his book Protogaea that the Earth was once molten

Gottfried Wilhelm Leibniz Bibliothek, Hannover Planets retain volatiles during accretion

• Moon, Mars, Mercury

• Water, carbon, …, helium!

NASA Elkins-Tanton. Some volatiles inside, some volatiles outside. The maximum water capacities of mantle minerals vary widely

Elkins-Tanton Maximum bulk water content retained in planetary mantle

Elkins-Tanton H O 2 Kind of meteorite: Dominant atmospheric specie

CM: H2O CI: H2O

LL: H2 H: H2

EH: H2 L: H2

CV: CO2 EL: CO Carbon Current day: N2 N2 Species Earliest degassed atmospheres vary with oxidation state, and all are a long way from current day

DATA from Schaefer and Fegley (2010), Hashimoto et al. (2007), Elkins-Tanton and Seager (2008) New York Times (2008) Life (1952) 0.7 H chondrites Carbonaceous chondrites Achondrites 0.6 L chondrites Enstatite chondrites

0.5 30 km deep ocean LL chondrites 0.4

0.3 Water [wt%] Water

0.2

0.1 5 km deep ocean

0.0 0.0 0.1 0.2 0.3 0.4 Carbon[wt%] Earth starting with 100 ppm bulk water produces dense atm that collapses upon cooling into global ocean 100s m deep Elkins-Tanton ; Data from Jarosewich (1990) Elkins-Tanton (2012) Ann.Rev. Elkins-Tanton (2010)