In the format provided by the authors and unedited.

1

Supplementary Information

Emergence of silicic continents as the lower crust peels

off on a hot plate-tectonic Earth

Priyadarshi Chowdhury1*, Taras V. Gerya2, Sumit Chakraborty1

1Ruhr-Universität Bochum, Institut für Geologie, Mineralogie & Geophysik,

Univertsitätsstrasse 150, 44801 Bochum, Germany.

2Swiss Federal Institute of Technology Zurich, Department of Earth Sciences,

Sonneggstrasse 5, 8092 Zurich, Switzerland.

Correspondence to: Priyadarshi Chowdhury (priyadarshi.chowdhury@rub.de)

Contents:

Supplementary text for ϕ, ϕTp, ξ

Supplementary text for Figure 3c and 4b

Supplementary Figures 1 to 9

Supplementary Table 1

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NGEO3010

NATURE GEOSCIENCE | www.nature.com/naturegeoscience 1

2

Supplementary text for ϕ, ϕTp, ξ

Parameter ϕ - The recycled volumes for each model are represented by a dimensionless

parameter ϕ (Supplementary Table 1) that is defined as-

𝜙 = {Recycled Volume in the model

Initial continental volume in the model 𝑥 1000}

The total initial volume of continental crust for various combinations of continental

thickness and oceanic plate length are-

Continental

thickness (km)

Oceanic Plate

length (km)

Initial continental

vol. (km3/km)

40 400 141573

40 600 131574

40 1000 117588

35 600 116951

No recycling is observed in models with 300 km long oceanic plate (Supplementary

Table 1) and therefore these models are not used for determining recycling volume/flux.

The definition of parameter ϕ makes the recycled volume independent of the dimension

of the continental plates, which is particularly useful for peeling-off caused recycling.

Model-selection for ϕTp and ξ- ϕTp denotes the average recycling magnitude at each

investigated mantle Tp and is calculated using ϕ’s of the selected representative models

corresponding to each studied mantle Tp. Same model-grouping is used to calculate the

characteristic recycling flux- ξ - at each studied mantle Tp as shown in Figure 4b. The

selected models at each investigated mantle Tp and the underlying rationale are given

below-

3

1275-1375 °C – All crustal-melting enabled models with strong LCC.

1425 °C - Model pprb. We have only a single experiment for this mantle Tp.

1475 °C - Models eprg and eprm.

1525 °C - Models eprd, eprh, eprj and eprl.

See Supplementary Table 1 for the model details. For calculating the ϕTp of

present-day mantle temperature conditions (Tp = 1275-1375 °C), we have only

considered the models in which crustal-melting is enabled (Supplementary Table 1).

Although our experiments show negligible effect of crustal-melting on the recycled

volume, the crustal-melting numerical experiments depict more realistic geodynamic

scenarios. If we include the crustal-melting absent models in the calculation, we obtain

a ϕTp = 5.2 ± 2.9 (n=31, Supplementary Table 1). This value is not significantly different

from our preferred ϕTp = 5.9 ± 3.2 (n=19, Supplementary Table 1) obtained from

crustal-melting enabled models. Furthermore, our models showing peeling-off

recycling due to the presence of weak LCC under present-day mantle Tp yield an

average ϕ = 77.2 ± 7.2 (n=7, Supplementary Table 1). Including this average ϕ for

peeling-off recycling in the calculation of ϕTp for present-day mantle temperature

conditions, requires the knowledge of the relative contribution of break-off recycling :

peeling-off recycling towards the net recycled magnitude. If we assume that

contribution from break-off recycling : peeling-off recycling is 95% : 5%, we obtain a

ϕTp = (0.95 x 5.9) + (0.05 x 77.2) = 9.4 and if the ratio is 90%:10%, then ϕTp = 12.99.

Therefore, our preferred ϕTp = 5.9 ± 3.2 represents the most conservative estimate of

recycling magnitude at present-day collisional orogens. Since the ratio (break-off

recycling : peeling-off recycling) is largely unknown, its introduction using an

arbitrarily chosen value would add unnecessary uncertainties to the ϕTp calculation.

Instead, we prefer to exclude the contribution of peeling-off recycling from ϕTp and

4

work with the limiting conservative estimate, recognizing that there is some

contribution of peeling-off to the overall recycling magnitude. Most significantly, all

of these values are far less than the ϕTp obtained for hotter mantle conditions (~177 and

306 at 1475 °C and 1525 °C Tp respectively; see text). Therefore, any choice of ϕTp for

modern mantle conditions from the range described above would have an insignificant

effect on the major conclusion of our study that recycling declined with the cooling of

the mantle.

For 1475 °C and 1525 °C, we constrained the ϕ only from LCC-eclogitization

models only because they correspond to the ages when a thick (≥ 20 km) completely

mafic (basaltic/gabbroic) LCC might have existed9-12. Recent studies show that the

major phase of felsification of upper continental crust was achieved by the end of

Archean11 while that of bulk continental crust continued till ~2.0-1.5 Ga (ref. 10). This

indicates that an extremely thick (≥20 km) totally mafic lower continental crust is viable

over the time-period when mantle Tp was ≥1475 °C.

Supplementary text for Figure 3c and 4b

In Fig. 3c, the exponential curve fitting is done in MATLAB using the function

‘fit’-(https://www.mathworks.com/examples/curvefitting/mw/curvefit-ex72685292-

fit-exponential-models-using-the-fit-function#1). The calculated r2= 0.94 suggests a

very good fit to the data. The interpolation of ξ values between the experimental data

points (Fig. 4b) is done using a shape preserving interpolation scheme called Piecewise

Cubic Hermite Interpolating Polynomial (PCHIP) in MATLAB-

(https://de.mathworks.com/help/matlab/ref/pchip.html ). This interpolation scheme

5

ensures that the shape of the interpolant is as exact as possible between the experimental

data points. Further, assuming that the ξ-value at ~2.1 Ga to be representative of

recycling flux during the entire late Archean since the onset of global plate-tectonics at

ca. 3 Ga, we have extrapolated the ξ-curve till 3 Ga.

Air / Water

Sediments

Felsic continental crust (FCC)

Mafic continental crust (MCC)

Basalt

Gabbro

Lithospheric Mantle Asthenosphere

Hydrated / weak-zone mantle

Molten Sediments

Molten FCC

Molten MCC

Molten Basalt

Molten Gabbro

1,4

00 k

m

4,000 kma

40 km

8 km

100500900

1,300

1,500

1,700

-5 -1 -5 -1For all lithologies - α = 3 x 10 K , β = 1 x 10 MPa , C =1 MPa

54Parameters for the Flow Laws

Materialρ0

3(kg/m )

64 k(0.00004.P (MPa){ x e }

(W/m/K at T )K

53Hr

3(µW/m )

53HL

(kJ/kg)

65,66Tsolidus

(K, at P Mpa)

65,66Tliquidus

(K, at P Mpa) 54Flow Law

Sediments

Felsic continental

crust (Upper)

Mafic continental

crust (Lower)

Basalt

Gabbro

Lithopshere -

asthenosphere

dry mantle

Hydrated / Weak-

zone wet mantle

3300 (solid)

3200 (solid)

2600 (solid)

2400 (molten)

2700 (solid)

2400 (molten)

2800 (solid)

2400 (molten)

3000 (solid)

2900 (molten)

3000 (solid)

2900 (molten)

0.64+807/(T+77)

0.64+807/(T+77)

0.64+807/(T+77)

1.18+474/(T+77)

1.18+474/(T+77)

0.73+1293/(T+77)

0.73+1293/(T+77)

1.50

1.00

0.25

0.25

0.25

0.022

0.022

300

300

380

380

380

-

-

889 + 17900/(P+54) 2+ 20200/(P+54) at

P<1200 MPa;

831 + 0.06P at

P >1200 MPa

973 - 70400/(P+354) 2+ 77800000/(P+354)

at P<1600 Mpa;

935 + 0.0035P + 20.0000062P at

P >1600 MPa

-

-

{{

1262 + 0.009P

1423 + 0.105P

-

-

Wet Quartzite

V = 8 J/mol/MPa , ω = 0.15a eff

Wet Quartzite

V = 12 J/mol/MPa , ω = 0.15a eff

Wet Quartzite/Plagioclase An75

V = 8 J/mol/MPa , ω = 0.15a eff

Wet Quartzite

V = 8 J/mol/MPa , ω = 0.0a eff

Plagioclase An75

V = 8 J/mol/MPa , ω = 0.6a eff

Dry Olivine

V = 8 J/mol/MPa , ω = 0.6a eff

Wet Olivine

V = 8 J/mol/MPa , ω = 0.6a eff

ρ - Standard density; k -Thermal conductivity; H -Radioactive heat production; H -Latent heat production; ω - effective internal friction coefficient; C - Cohesion; A -Material 0 r L eff D

constant; n -Stress exponent; E -Activation energy; V -Activation volume; α -Thermal expansion coefficient; β - Isothermal compressibility. Physical properties are taken from refs. a a

53-54 and 64-66 (METHODS) as indicated.

17 22Wet Quartzite - A = 1.97 x 10 Pa.s, n = 2.3, E - 154000 J/mol Plagioclase An - A = 4.80 x 10 Pa.s, n = 3.2, E - 238000 J/mol D a 75 D a

16 20Dry Olivine - A = 3.98 x 10 Pa.s, n = 3.5, E - 532000 J/mol Wet Olivine - A = 5.01 x 10 Pa.s, n = 4.0, E - 470000 J/molD a D a

b Physical properties of lithologies used in the 2D numerical experiments

Supplementary Figure 1. Numerical model architecture. See Methods for details. a, Compositional morphology of the

full model domain. Enlarged blue box shows the geometry of the continent-ocean passive margin and the weak-layer

prescribed for subduction initiation. Pink box shows the oceanic crust morphology. All mechanical boundaries satisfy free-

slip boundary condition. Dark blue lines are isotherms with numbers indicating temperature in °C. Colour code for different

materials is shown. b, Table showing the physical properties of lithologies used in 2D numerical experiments.

6

11.82 Myr 14.03 Myr

13.37 Myr 28.75 Myr

8.71 Myr 29.40 Myr

20.13 Myr 21.60 Myr

1,900 2,300 2,700 (km)

1,900 2,300 2,700 (km)

40

0 k

mOceanic-plate Cooling Age

Thinner continental crust

Subduction Velocity

Oceanic-plate Length

slab-break-off within oceanic plate

90

km

75 km

100

500

900

1,300

a

c

e

g

b

d

f

h

Supplementary Figure 2. Parametric study of break-off recycling under present-day mantle T . cf. with the reference p

model in Fig. 1. a-b, 40-Myr (pcaa) and 100-Myr (pckk) old oceanic plate. c-d, Thinner (35 km) continents with 40-Myr

(rcab) and 80-Myr (rcfb) old oceanic plate. e-f, 7 cm/yr (pcdd) and 2 cm/yr (dcaa) convergence rate. g-h, 300-km (pccc) &

1000-km (pcqq) long oceanic plate. Blue boxes (75 km x 90 km) enlarge the recycled volumes for visual comparison. Dark

blue lines are isotherms. Dotted red lines indicate the depth of no-return. See Supplementary Table 1 for model details.

7

a

b

c

d

e

f

11.54 Myr 76.09 Myr

36.11 Myr 109.96 Myr

113.32 Myr66.17 Myr

14.47 Myr

12.94 Myr

27.23 Myr

27.61 Myr

14.57 Myr

126.61 Myr

1,500 km5

00

km

Slabbreak-off

Slabbreak-off

Slab break-off

No peeling-off

Drip-off

Drip-off

Very limited peeling-off; orogenic arrest

Extensive double-sided peeling-off

No peeling-off

No peeling-off

Stronger peeling-off

100500

900

1,300

1,500

100500

9001,300

1,500

100500

9001,300

1,500

100500

9001,300

1,500

100500

9001,300

1,500

1,700

100500

9001,300

1,500

1,700

1275 °C Mantle Tp

1325 °C Mantle Tp

1375 °C Mantle Tp

1425 °C Mantle Tp

1475 °C Mantle Tp

1525 °C Mantle Tp

Supplementary Figure 3. Influence of mantle T on the recycling dynamics . a, b, and c, Models with 1275 °C (pcff), p

1325 °C (impa) and 1375 °C (ppra) mantle T respectively, all showing only break-off recycling. d, e, and f, Models with p

increasingly higher mantle T of 1425°C (pprb), 1475 °C (pprc) and 1525°C (pprd) respectively, showing increasing degree p

of peeling-off. Compare the temporal and spatial extent of peeling-off. Dark blue lines are isotherms with numbers

indicating temperature in °C. Dotted red lines indicate the depth of no-return. See Supplementary Table 1 for model

details.

8

38.75 Myr

2.02 Myr

33.68 Myr

1.92 Myr

29.78 Myr

65.38 Myr

5.95 Myr

6.30 Myr

43.25 Myr

1,000 2,5001,500 2,000 1,000 2,5001,500 2,000

1,000 2,5001,500 2,000

1,000 2,5001,500 2,000

50

0 k

m5

00

km

1,000 3,0002,000

50

0 k

m (km) (km)

(km)

(km)

(km)

75

0 k

m

10 Myr oceanic plate, 1475 °C Mantle T , strong LCC (An )p 75

20 Myr oceanic plate, 1475 °C Mantle T , strong LCC (An ) p 75

20 Myr oceanic plate, 1525 °C Mantle T , strong LCC (An ) p 75

1000 km - 80 Myr oceanic plate, 1525 °C Mantle T , strong LCC (An ) p 75

10 Myr oceanic plate, 1475 °C Mantle T , weak LCC (WQ)pa

c

d

b

e

410 km

660 km

410 km

660 km

410 km

660 km

100500

9001,300

1,500

1,700

100500

9001,300

1,500

1,700

100500

9001,300

1,500

1,700

100500

9001,300

1,500

1,700

100 500900 1,300

1,500

1,700

Supplementary Figure 4. Recycling after shallow slab break-offs under hotter mantle conditions. Models, either with

≤ 20-Myr-old oceanic plate and strong LCC (a, c, and d, models ppre, pprg and pprh respectively) or with 1000-km-long

oceanic plate (e, model ppri) show no peeling-off after shallow break-off. Only weak LCC model with 10-Myr-old oceanic

plate (b, model wpre) shows peeling-off after shallow break-off. Dark blue lines are isotherms with numbers indicating

temperature in °C. Dotted red lines indicate the depth of no-return. See Supplementary Table 1 for model details.

9

7.19 Myr

11.17 Myr

20.94 Myr

48.35 Myr

7.51 Myr

40.86 Myr

50.38 Myr

73.98 Myr

1,000 2,5001,500 2,000 (km)

50

0 k

m

Slabbreak-off

Onset of Peeling-off

Onset of Peeling-off

Slab break-off

c Crustal melting (reworking) scenarios

1,000 2,5001,500 2,000 (km)

a 80-Myr-old oceanic plate b 20-Myr-old oceanic plate

drip-off

Crustal meltingand

relamination

(deeper) LCC and (shallower) UCC, sediments melting

mafic crust melting

new crust

1650 km 1950 km

200 k

m

200 k

m

1500 km 1900 km

00

2000 km1600 km

200 k

m0

500900

1,3001,500

1,700

100500

9001,300

1,500

1,700

100

viscousnecking

recycledLCC

9001200

9001200

9001200

Supplementary Figure 5. Influence of LCC eclogitization on peeling-off recycling under hotter mantle conditions.

Evolution of models with 80-Myr-old (a, eprd) and 20-Myr-old (b, eprh) oceanic plates at 1525 °C mantle T ; primarily p

varying in the slab break-off depth. Crustal melting facilitates the peeling-off initiation. Dark blue lines are isotherms with

numbers indicating temperature in °C. Dotted red lines indicate the depth of no-return. c, Enlarged figures show massive

melting of pre-existing crust and sediments leading to crustal growth. Note that LCC melts at greater depths while UCC and

sediments preferentially, melt at shallower depths. Margin-color of the figures corresponds to the color of the boxes within

panel (a) and (b). See Supplementary Table 1 for model details.

10

1,000 1,500 2,000 2,500 (km)

1,000 1,500 2,000 2,500 (km)

50

0 k

m

log η Map (Pa.s)10

Slab break-off

whole plate subductionand slab break-offs

Peeling-off Front

Slab break-off

Peeling-off

Slab break-off

3Density Map (kg.m )

a Higher radioactive heat generation (H ) ; felsic UCC ; 1525 °C Mantle Tr p

b Higher H ; Mafic and strong UCC ; 1525 °C Mantle Tr p c Higher H ; Mafic and weak UCC ; 1525 °C Mantle Tr p

UCC-LCCboundary

MOHOUCC-LCCboundary

MOHO

6.67 Myr

7.16 Myr

20.33 Myr

20.33 Myr

20.33 Myr 22.77 Myr

22.77 Myr

22.77 Myr

7.76 Myr

26.39 Myr

100500

9001,300

1,500

100500

9001,300

1,500

1,700

1,700

19 20 21 22 23 24 25

100500

9001,300

1,500

1,700

2.4 2.8 3.2 3.6 4.0 4.22.6 3.0 3.4 3.8

3x 10

Supplementary Figure 6. Influence of higher radioactive heat generation (H ) and mafic UCC on recycling under r

hotter mantle conditions. a, model eprl with 2.25x and 1.5x higher crustal- and mantle- H respectively, at 1525 °C mantle r

T . Slab break-off depth decreases due to higher H (cf. with Supplementary Fig. 5a). b-c, Models amcb and amce with p r

stronger and weaker mafic dominated UCC, respectively at 1525 °C mantle T . Crustal H is 2.25x higher while mantle H is p r r

1.5x higher. Density and viscosity maps for the last compositional panel are shown. Arrows indicate the velocity field. Dark

blue lines are isotherms with numbers indicating temperature in °C. Dotted red lines indicate the depth of no-return. See

Supplementary Table 1 for model details.

11

a

b

c

d

f

g

h

i

e j

8.12 Myr

11.11 Myr

16.54 Myr

23.81 Myr

21.93 Myr

24.43 Myr

25.66 Myr

31.05 Myr

Compositional Map

1,000 1,500 2,000 2,500 (km)

1,000 1,500 2,000 2,500 (km)

1475 °C Mantle Tp1275 °C Mantle Tp

50

0 k

m

log η Map (Pa.s)10

Crustal decoupling and

uprise

Mantle inflow

Coherent andcontinous Peeling-off

LCC

LCC melting

LCC Peeling-off

Development of Peeling-off Front

Decoupling within LCC

Slab break-off

Break-off recycling

Crustal melting

19 20 21 22 23 24 25

31.05 Myr 23.81 Myr

100500900

1,300

1,500

100500

9001,300

1,500

1,700

Supplementary Figure 7. Recycling involving weak LCC at present-day and hotter mantle conditions. Evolution at

1275°C mantle T (wdhh) shows decoupling of subducted continental crust from SCLM (a), followed by slab roll-back (b). p

Mantle inflow along the subduction channel (c) triggers the SCLM+LCC peeling-off (d). No slab break-off occurs. Evolution

at 1475 °C mantle T (wprc) shows shallow slab break-off (f) and crustal melting (g) resulting in the peeling-off (h-i). Inset p

(in panel g) shows melting induced indentation within the LCC. e-f, show viscosity maps for panels (d) and (i), respectively.

Dark blue lines are isotherms with numbers indicating temperature in °C. Dotted red lines indicate the depth of no-return.

See Supplementary Table 1 for model details.

12

j

0

0.4

0.8

1.2

1.6

10%

30%

50%

70%

chosenaverage

a b c d

e

i

k

f g h

33

Recy

cled V

olu

me (

x10

km

/km

)

33

Recy

cled V

olu

me (

x10

km

/km

)

pcaapcbb

pcddpcff pcjj

600

400

600

400

600

400

600

400

600

400

600

1000

1000

40

60

80

40

60

100

80

40

80

40

80

40

60

80

40

60

80 2 5 7 2 5 72 5 7 5

10 5

10 5

10

0

0.5

1.0

1.5

0

5

10

15

40

80

100

80

100

80

100 5 7

10 5 7

10

80

20

eprd

eprl

0

15

30

45

Mantle T

(°C

)p

Recyclin

g fl

ux ξ

-1

(100 M

yr

)

Age (Ga)

1,600

1,500

1,400

1,300

0.0

0.1

0.2

0.3

0.4

0.5

0.5 1 1.5 20 2.5 3 3.5 4

present-day range

0.00

0.02

0.04

0.06

0 200 400 600

Age (Ga)

0.5 1 1.5 20 2.5 3 3.5 4

0

5

10

15

20

25

30

35

Cum

mula

tive r

ecycle

d

3volu

me (

bill

ion k

m)

10%

30%

50%

70%chosenaverage

ξavgξmodel

OPL - Oceanic plate length (km)OPA - Oceanic plate cooling-age (Myr)NSV - Net subduction velocity (cm/yr)H - Radioactive heat generation.r

Recycle

d v

olu

me

3dis

trib

ution (

bill

ion k

m)

dca

a*

pca

a*

pcd

d*

dca

ap

caa

pcd

d

dcb

b*

pcf

f*p

chh

*

rca

arc

ab

rcjj

rcjb

rcfb

rcff

pca

a*

pcj

j*p

cff*

pck

k

dca

a*

dcb

b*

pca

ap

cjj

pcf

f

pcp

pp

cqq

rca

arc

jbrc

ff

rca

brc

jjrc

fb

pca

ap

cbb

pcd

d*

pcf

f*

pch

h*

pcg

g*

pce

e*

pci

i*

pca

a*

pcb

b*

pcf

fp

cqq

pcp

p

wdhh

wdee

wdaa

wdgg

wdff

wdbb

wdaa#

wdaa

wdbb

wdee

wdff

wdhh

wdgg

eprh

eprd

2.2

5x

hig

he

r cr

ust

al H

r

Norm

al cr

ust

al H

r

Present M-T ; p

Melting vs Non-meltingPresent M-T ; OPL (km)p Present M-T ; OPA (Myr)p Present M-T ; NSV (cm/yr)p

Present M-T ; p

OPA (Myr)Present M-T ; p

NSV (cm/yr)Hotter M-T ; p

OPA (Myr)Hotter M-T ; p

Hr

Strong LCC

Strong LCC with LCC-eclogitization

Weak LCC

Strong LCC and no crustal melting

Johnson et al. (ref. 16)

Herzberg et al. (ref. 17)

Mantle T investigated p

in this study

Mantle T vs. Earth’s age, p

redrawn after-

Supplementary Figure 8. Plots of the variations in recycling magnitude (a-h), evolution of recycling flux (i) and net

recycled volumes (j-k) with the age of Earth. Histograms for strong LCC models showing negligible effect of crustal

melting on break-off recycling (a) but generally increasing recycling with increasing oceanic plate length (b), oceanic plate

cooling age (c) and subduction velocity (d). Weak LCC models show that oceanic plate age increases the recycled volume

(e), whereas subduction velocity has no correlation (f). Models with LCC eclogitization under hotter mantle conditions show

no significant change in recycling magnitude with increasing oceanic plate cooling age (g) and radioactive heat generation

(h). See Supplementary Table 1 for model details. i, The recycling flux ξ is linked with the Earth's age through the existing

mantle T - Earth's age relations [redrawn after the permission from Elsevier for Herzberg et. al. (ref. 17; p doi:10.1016/j.epsl.

2010.01.022 and Macmillan Publishers Ltd: Nature Geoscience for Johnson et al. (ref. 16; doi:10.1038/ngeo2019)]. Green

13

14

and orange dots (and lines) show ξ-calculation using two different orogenic durations (see text and Fig. 4). Inset shows the

enlarged ξ-evolution from 200 Ma till present-day. j-k, Plot showing the distribution of recycled volume and the evolution of

cumulative recycled volume with the age of Earth for different orogenic continental volume %, respectively.

1,500 km

50

0 k

m

a

b

c

d

e

f

g

12

75

°C

Ma

ntle

Tp

13

25

°C

Ma

ntle

Tp

1375 °

C M

an

tle T

p1425 °

C M

antle

Tp

1475 °

C M

antle

Tp

1525 °

C M

antle

Tp

1525 °

C M

antle

Tp

LC

C E

clogiti

zatio

n

log η (Pa.s)10

2520 21 2219 23 24

14.27 Myr

12.94 Myr

11.54 Myr

36.11 Myr

27.23 Myr

112.58 Myr

48.35 Myr

Slab break-off

Slab break-off

Limited peeling-off

Stronger peeling-off

Extensive double-sidedpeeling-off

Extensive peeling-off

Slab break-off

Supplementary Figure 9. Viscosity maps

showing the evolving orogenic-recycling

dynamics with mantle T for strong LCC. p

a, model pcff with 1275 °C mantle T . b, model p

impa with 1325 °C mantle T . c, model ppra with p

1375 °C mantle T . d, model pprb with 1425 °C p

mantle T . e, model pprc with 1475 °C mantle T . p p

f, model pprd with 1525 °C mantle T . g, LCC p

eclogitization enabled model eprd with 1525 °C

mantle T . Arrows indicate the velocity field. p

Corresponding compositional maps are shown

in Supplementary Fig. 3. See Supplementary

Table 1 for model details.

15

Present mantle Tp; Strong LCC (An75)

pcaa* 1275 40 40 600 5 Slab break-off (SB) recycling (CR) 633 4.81 57/43 100/00 6 11.9 -

pcbb* 1275 40 40 400 5 SB led CR 333 2.35 38/62 100/00 0 15.0 -

pccc* 1275 40 40 300 5 SB within oceanic plate; No CR 0 0.00 0 0 0 - -

pcdd* 1275 40 40 600 7 SB led CR 813 6.18 64/36 100/00 0 8.6 -

pcee* 1275 40 40 400 7 SB led CR 333 2.35 39/61 100/00 0 13.6 -

pcff* 1275 40 80 600 5 SB led CR 899 6.83 54/46 100/00 0 14.2 -

pcgg* 1275 40 80 400 5 SB led CR 296 2.09 16/84 100/00 0 25.9 -

pchh* 1275 40 80 600 7 SB led CR 879 6.68 55/45 100/00 0 10.3 -

pcii* 1275 40 80 400 7 SB led CR 443 3.13 17/83 100/00 0 20.2 -

pcjj* 1275 40 60 600 5 SB led CR 729 5.54 57/43 100/00 0 13.1 -

dcaa* 1275 40 40 600 2 SB led CR 568 4.32 55/45 100/00 36 28.6 -

dcbb* 1275 40 80 600 2 SB led CR 778 5.91 49/51 100/00 0 42.2 -

pcaa 1275 40 40 600 5 SB led CR 635 4.83 52/48 100/00 0 11.5 yes

pcbb 1275 40 40 400 5 SB led CR 348 2.46 39/61 100/00 0 15.6 yes

pcdd 1275 40 40 600 7 SB led CR 684 5.20 59/41 100/00 0 8.6 yes

pcff 1275 40 80 600 5 SB led CR 893 6.79 55/45 100/00 0 14.4 yes

pcjj 1275 40 60 600 5 SB led CR 703 5.34 58/42 100/00 4 12.7 yes

pckk 1275 40 100 600 5 SB led CR 1375 10.45 67/33 100/00 489 14.0 yes

dcaa 1275 40 40 600 2 SB led CR 628 4.77 48/52 100/00 41 29.3 yes

pcpp 1275 40 40 1000 5 SB led CR 642 5.46 56/44 100/00 47 12.7 yes

pcqq 1275 40 80 1000 5 SB led CR 718 6.11 51/49 100/00 66 21.5 yes

rcaa 1275 35 40 600 10 SB led CR 531 4.54 66/34 100/00 0 7.1 yes

rcab 1275 35 40 600 5 SB led CR 508 4.34 68/32 100/00 38 13.2 yes

rcff 1275 35 80 600 10 SB led CR 360 3.08 19/81 100/00 0 23.6 yes

rcfb 1275 35 80 600 5 SB led CR 330 2.82 23/77 100/00 0 28.8 yes

rcjj 1275 35 60 600 5 SB led CR 778 6.65 64/36 100/00 0 18.5 yes

rcjb 1275 35 60 600 10 SB led CR 756 6.46 63/37 100/00 0 15.3 yes

rcfc§ 1275 35 80 600 5 SB led CR 278 2.38 22/78 100/00 0 36.0 yes

impa 1325 40 80 600 5 SB led CR 2182 16.58 62/38 100/00 2 12.9 yes

imra 1325 35 80 600 5 SB led CR 904 7.73 75/25 100/00 3 16.9 yes

ppra 1375 40 80 600 5 SB led CR 680 5.17 88/12 100/00 8 40.9 yes

Higher mantle Tp; Strong LCC (An75)

pprb 1425 40 80 600 5 SB; limited peeling-off (drip-offs); CR 1300 9.88 52/48 48/52 40 78.8 yes

pprc 1475 40 80 600 5 SB; peeling-off (drip-offs); CR 1902 14.46 28/72 23/77 60 126.6 -

pprd 1525 40 80 600 5 SB; peeling-off (drip-offs); CR 6421 48.80 008/92 005/95 85 131.8 -

ppre 1475 40 10 600 5 very shallow SB; CR 524 3.98 51/49 100/00 45 72.9 -

pprf 1525 40 10 600 5 very shallow SB; CR 154 1.17 86/14 78/22 36 14.1 -

pprg 1475 40 20 600 5 very shallow SB; CR 243 1.85 100/0 100/00 2 16.9 -

pprh 1525 40 20 600 5 very shallow SB; CR 238 1.81 87/13 78/22 0 65.4 -

ppri 1525 40 80 1000 5 very shallow SB; CR 317 2.70 55/45 100/00 - 43.3 -

Higher mantle Tp; Strong LCC (An75) with eclogitization†

eprd 1525 40 80 600 5 SB; peeling-off (drip-offs); CR 41510 315.49 008/92 001/99 75 81.9 yes

eprg 1475 40 20 600 5 SB; peeling-off (drip-offs); CR 11651 88.55 14/86 002/98 50 104.9 yes

eprh 1525 40 20 600 5 SB; peeling-off (drip-offs); CR 39675 301.54 012/88 00/100 335 103.0 yes

eprj 1525 40 20 1000 5 SB; peeling-off (drip-offs); CR 37696 320.58 16/84 002/98 207 111.5 yes

eprl** 1525 40 80 600 5 SB; peeling-off (drip-offs); CR 37894 288.01 19/81 001/99 8 44.9 yes

eprm** 1475 40 20 600 5 SB; peeling-off (drip-offs); CR 35172 267.32 16/84 001/99 10 55.3 yes

Higher mantle Tp; Mafic UCC with LCC (An75) eclogitization†

amcba 1525 40 80 600 5 subduction with episodic SB; CR - - - - - - -

amceb 1525 40 80 600 5 SB; peeling-off (drip-offs); CR - - - - - - -

Present mantle Tp; Weak LCC (WQ)

wdaa# 1275 40 40 600 10 no SB; coherent peeling-off; CR 8382 63.71 003/97 00/100 0 40.1 -

wdaa 1275 40 80 600 10 no SB; coherent peeling-off; CR 9597 72.94 011/89 00/100 0 26.7 -

wdbb 1275 40 100 600 10 no SB; coherent peeling-off; CR 10725 81.51 012/88 001/100 0 29.4 -

wdee 1275 40 80 600 7 no SB; coherent peeling-off; CR 10032 76.25 011/89 00/100 17 30.4 -

wdff 1275 40 100 600 7 no SB; coherent peeling-off; CR 11181 84.98 014/86 00/100 42 34.5 -

wdgg 1275 40 100 600 5 no SB; coherent peeling-off; CR 11340 86.19 012/88 00/100 9 37.3 -

wdhh 1275 40 80 600 5 no SB; coherent peeling-off; CR 9869 75.01 012/88 00/100 29 33.6 -

Supplementary Table 1. Model-conditions and results of 2D numerical experiments for orogenic continental recycling.

Net ϕ

Continental recycling (CR) magnitude

Cooling

age (Myr)

Length (km)

UCC/

LCC (%)

Recy.

Vol. (km3/

km)

Sed.

(km3/

km)

used in

ϕT p -ξ

calc

Result break-off /

peeling-off

recy. (%)

t recy

(Myr)

Model

Mantle

Poten.

Temp. (K)

Cont.

thick. (km)

Oceanic plate Net

subduc.

Vel. (cm/a)

16

Higher mantle Tp; Weak LCC (WQ)

wprb 1425 40 80 600 5 SB; coherent peeling-off; CR 13850 105.26 006/94 008/92 28 30.2 -

wprc 1475 40 80 600 5 SB; coherent peeling-off; CR 16093 122.31 006/94 009/91 29 25.5 -

wprd 1525 40 80 600 5 SB; coherent peeling-off; CR 17912 136.14 005/95 007/93 128 36.7 -

wpre 1475 40 10 600 5 SB; coherent peeling-off; CR 15296 116.25 003/97 002/98 442 39.3 -

wprg 1475 40 20 600 5 SB; coherent peeling-off; CR 12565 95.50 004/96 004/96 57 25.6 -

wprh 1525 40 20 600 5 SB; coherent peeling-off; CR 12588 95.67 004/96 003/97 3 19.3 -

* Crustal melting absent§ Thermally 100 km wide ocean-continent transition. In all other models, 200 km width is used.† Gabbroic LCC (3000 kg/m3). In all other models, LCC is mafic continental crust (2800 kg/m3).** Higher radioactive heat (H r ) generation. Crust/sediments H r increased by 2.25x (eprl ) and 1.75x (eprm ). Mantle H r increased by 1.5x.a,b Dominantly mafic UCC (2850 kg/m3) with stronger (An75) rheology in amcb and weaker (WQ) rheology in amce. Recycling fluxes are not calculated for these models.

Net ϕ

Continental recycling (CR) magnitude

Cooling

age (Myr)

Length (km)

UCC/

LCC (%)

Recy.

Vol. (km3/

km)

Sed.

(km3/

km)

used in

ϕT p -ξ

calc

Result break-off /

peeling-off

recy. (%)

t recy

(Myr)

Model

Mantle

Poten.

Temp. (K)

Cont.

thick. (km)

Oceanic plate Net

subduc.

Vel. (cm/a)

17

Supplementary Table 1. Model-conditions and results of 2D numerical experiments for orogenic continental recycling.