thermal evolution of an early magma ocean in interaction ...€¦ · magma ocean: thermal evolution...

Thermal evolution of an early magma ocean in interaction with the atmosphere

T. Lebrun (1), H. Massol (1), E. Chassefière (1), A. Davaille (2), E. Marcq (3), P. Sarda (1), F. Leblanc (3), G. Brandeis (4)

(1) IDES/CNRS/ Univ. Paris Sud, Orsay, France (2) FAST/CNRS/ Univ. Paris Sud, Orsay, France

(3) LATMOS/CNRS/Univ. of Versailles St Quentin, France, (4) IPGP/CNRS/Univ. Paris 7, France

• Water condensation (Earth/Venus/Mars)?"

• Cooling of magma ocean sets the initial conditions for tectonics regime and habitability conditions."

• Duration of the magma ocean phase on the three terrestrial planets? Sequential or continuous?"

• Influence of volatile contents, distance to the Sun, radioactive heating "

" "

Motivation"

This parametric approach complete "existing full 3-D convection numerical

simulations. "

Scheme of the solidifying magma ocean adapted from (Solomatov, 2000).

Magma ocean: Thermal evolution model"

Abe, 1993

Turbulentconvection

Nucleation of new crystals in the descending convective plumes

Heat !ux

RP

Rb

Atmosphere

Rl

Rs

Totally liquid zone

Partially liquid zone

Solid zone

RF

Scheme of the solidifying magma ocean adapted from (Solomatov, 2000).

Magma ocean: Thermal evolution model"

€

Ra =αgΔTl3

κν

Heat conservation

Thermal convection

n=1/3 to 1/5

€

IdTp

dt= Rp

2Fs[ ] +Qr

Atmospheric model"

-1D radiative-convective model

-Massive H20-CO2 atmosphere

-Includes: .Convection in the troposphere .Presence of water clouds .Condensation of water vapour .Pressure contribution of N2 gas

-Thermal IR opacities computed using a k-correlated code

Atmospheric model"

Teff"

T(z) profile with Ts=1400 K, PCO2 = 100 bars and PH2O=300 bars"

After (Marcq, 2011)!

(Ex: Earth inventory)

Coupled Model"

- Volatile exchange between Magma Ocean and atmosphere: Atmosphere in equilibrium with magma ocean liquid

- Heat conservation

- Initial conditions: . Tp=4000°K .no atmosphere .0.014 to 0.14 wt% H20 or CO2 (100<P<1000 bars)

Magma Ocean History"

Magma Ocean History"

0

50

100

150

200

250

Parti

al p

ress

ure

(Bar

)

Totally molten stage

Partially molten stage

"Mush" stage

(c)

1000

3000

2000

6000

4000

Tem

pera

ture

(K)

5000

70004000K

3600K

2800K1800K

1400K

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)

500 1000 1500 2000 2500 3000

3000

2000

1000

4000

5000

6000

7000

0

Tem

pera

ture

(K)

Depth (Km)

4000K3600K

2800K1800K

1400K

(a) (d)

500 1000 1500 2000 2500 30000Depth (Km)

0

50

100

150

200

250

Parti

al p

ress

ure

(Bar

)



"Mush" stage

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)

(f )

0

0.60.70.80.91.0

Liqu

id vo

lum

e fra

ctio

n



"Mush" stage

(b)

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)



"Mush" stage

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)

(e)

0.50.40.30.20.1

0

0.60.70.80.91.0

0.50.40.30.20.1

Liqu

id vo

lum

e fra

ctio

n

Water condensation at the beginning of the mush stage

Influence of atmosphere"No atmosphere" Atmosphere"

Influence of Volatile content"

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)

0

40

60

80

100

Part

ial p

ress

ure

(Bar

)

0100

200

300400500600700

Part

ial p

ress

ure

(Bar

)



"Mush" stage



"Mush" stage

(a)

(b)

20

800900

120

Tim

e (M

yr)

0Initial volatile amount (10 -2 Wt%)

101

100

10-1

5 10 1510-2

1

2

3

H20

CO2

End of Magma ocean sensitive to volatile content

Lebrun et al, JGR Planet, in press

Influence of Distance to the Sun"Ti

mes

(Myr

)

450 Incident solar !ux (Wm-2)

500400300200100 550

101

100

10-1

102

350250150

Distance from the sun (AU)1.55 1.26 1.10 0.98 0.89 0.83 0.77 0.73 0.69 0.66

10-6 10-5 10-4 10-3 10-2 10-1 100 101 102

Time (Myr)

500

0

1000

1500

2000

2500

3000

35004000

Tem

pera

ture

(K)

500

0

1000

1500

2000

2500

3000

3500

4000

Tem

pera

ture

(K)



"Mush" stage

(a)

2500

0

3500

1500

500

1000

3000

2000

Tem

pera

ture

(K)

4000



"Mush" stage



"Mush" stage

(b)

(c)

Venus

Earth

Mars

Water Condensation"

No water

condensation

Water condensation

500 600450 550300 400350

14

2

10

Initi

al H 2

O co

nten

t (10

-2 W

t%)

4

6

8

12

40

30

20

10

0.2

Vapor water condensation time (M

yr)

Distance from the sun (AU)0.89 0.77 0.69 0.630.83 0.73 0.66

Incident solar !ux (Wm-2)

Water Condensation"

No water

condensation

Water condensation

500 600450 550300 400350

14

2

10

Initi

al H 2

O co

nten

t (10

-2 W

t%)

4

6

8

12

40

30

20

10

0.2


yr)



14

2

10

Initi

al CO

2 con

tent

(10 -2

Wt%

)

No water condensation

Water condensation

4

6

8

12

300 500200 400100 600

40

30

20

10

0.2

Distance from the sun (AU)1.55 1.10 0.89 0.77 0.69


yr)

0.63


Water Condensation"

No water

condensation

Water condensation

500 600450 550300 400350

14

2

10

Initi

al H 2

O co

nten

t (10

-2 W

t%)

4

6

8

12

40

30

20

10

0.2


yr)



14

2

10

Initi

al CO

2 con

tent

(10 -2

Wt%

)


Water condensation

4

6

8

12

300 500200 400100 600

40

30

20

10

0.2

Distance from the sun (AU)1.55 1.10 0.89 0.77 0.69


yr)

0.63


300 500200 400100 600

Radi

us o

f the

pla

net (

km)

7000

6000

5000

4000

3000


Water condensation

40

30

20

10

0.2

Distance from the sun (AU)1.55 1.10 0.89 0.77 0.69 0.63


yr)


Perspectives"

Albe

do

0.1

0.3

0.5

0.7

0.9

0.6

0.4

0

0.2

0.8

1.0

Distance from the Sun (AU)1 1.2 1.4 1.6 1.80.2 0.4 0.6 0.8

V E M

Water Condensation No

- Atmosphere delays the end of magma ocean

- Initial CO2 content controls the ability to condensate a water ocean for distance to the Sun greater than 0.66 AU.

-Time to condensate water ocean on Earth ~ 1 Myr Mars ~ 0.1 Myr Venus ~10 Myr

-tend < accretion time => water ocean can escape

-Magma ocean model: rotation, petrology,… -Atmospheric model, initial volatile content -Multiple impact scenario

Conclusions"

thermal evolution of an early magma ocean in interaction ...€¦ · magma ocean: thermal evolution...

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