1
Supplementary Material for
2
Circum-Arctic mantle structure and long-wavelength topography since the
3
Jurassic
4
Shephard, G. E., Flament, N., Williams, S., Seton, M., Gurnis, M., and Müller, R.D.
5
6
Supplementary Methods
7
Absolute reference frames and Net Lithospheric Rotation (NLR)
8
The hybrid absolute plate reference frame of Seton et al. (2012) (case C2) is
9
based on a moving Indian/Atlantic hotspot model (O’Neill et al., 2005) for times
10
younger than 100 Ma and on a True Polar Wander (TPW)-corrected
11
palaeomagnetic model (Steinberger and Torsvik, 2008) for older times (Table 2).
12
The use of the hybrid absolute plate motion of O’Neill et al. (2005) and
13
Steinberger and Torsvik (2008) implies NLR in excess of 0.4°/Myr between ~40-
14
60, 65-80, 110-115 and 180-215 Ma (Figure S13). NLR is large at present-day in
15
a Pacific hotspot reference frame (~ 0.44°/Myr HS3, Conrad and Behn, 2010)
16
and geologically recent NLR (since ~ 50 Ma) has an overall westward direction
17
with
18
~0.11+_0.03°/Myr) depending on reconstructions (e.g. Ricard et al., 1991;
19
Becker, 2006; Torsvik et al., 2010). While a component of NLR throughout time
20
may be real, increasing uncertainty of the plate reconstruction back in time may
21
result in unrealistically large NLR, especially concerning the velocities of the
22
large plates comprising Panthalassa. Our plate models are constructed with
23
continuously closing plates (Gurnis et al., 2012), which allow us to define global
24
surface velocity fields through time and to calculate the NLR implied by a given
25
reference frame as in Torsvik et al. (2010) and Alisic et al. (2012).
estimated
rates
previously
ranging
between
1.5-9 cm/year
(or
26
27
We used three approaches to minimize NLR from the absolute reference frame in
28
our geodynamic model cases (Tables 2 and S3); (i) computing and removing the
29
NLR from the plate reconstruction (case C3), (ii) including a low-viscosity
30
asthenosphere to decouple the lithosphere from the sub-asthenospheric mantle
31
(cases C2 and C8) and (iii) changing the absolute reference frame by using the
32
finite rotations from the moving hotspot reference frame of Torsvik et al. (2008)
33
rather than that of O’Neill et al. (2005) for ages younger than 70 Ma (models C1,
34
C4, C5 as well as C6-C8). We also change the absolute motion of the Pacific
35
during the Cenozoic by changing the poles of rotation between east and west
36
Antarctica (from Cande et al. [2000] to Granot et al. [2013]). The resultant NLR
37
for this latter absolute plate motion model (C1, C4-C8) is < 0.4°/Myr for all times,
38
although it is slightly more elevated for the last 20 Ma (~ 0.18°/Myr) than the
39
previous reference frame (O’Neill et al., 2005; Steinberger and Torsvik, 2008:
40
~0.12°/Myr; C2, Table 2, Fig. S13).
41
42
In addition to differences in the absolute reference frame we explored different
43
mantle parameters including viscosity profile, initial slab depth, slab dip and
44
basal layer density (Figs. S3, S4, S6-8, S10-15, Table S3). We find that changes in
45
dynamic topography are small and do not affect our main conclusions. Rates of
46
dynamic topography for alternative cases C3-C5 are usually in the order of ±5
47
m/Myr from those of C1 (Table S1, S2), and are compatible with the geological
48
constraints presented in the main text (see Figs. 7e-h). Notably, under Eurasia,
49
alternative cases C3-C5 (Figs. S10) predict a similar two-slab configuration
50
(Mongol-Okhotsk slab to the west and north-eastern Panthalassa slab to the
51
east) to those of C1 but with locations offset by ± 5° longitude (10° to the east for
52
slab (m) in C5, though the use of a depth-dependent viscosity was not ideal, see
53
below). Case C4, illustrates that increasing the slab dip does not significantly
54
change the results.
55
56
In addition to C1-C5 and in the interests of illustrating the main suite of
57
parameters tested (see also Flament et al., 2014) we present an extended set of
58
eight cases (C1-C8) in Figs. S14 and S15. These figures illustrate our
59
investigation of the effect of rheological parameters on lower mantle structure
60
and our selection of a set of parameters for C1 by visual comparison between
61
predicted mantle temperature and seismic tomography along arbitrary cross-
62
sections. For example, C6 and C8 both include a linear increase in viscosity for
63
the lower mantle; looking under Eurasia (Fig. S15) in case C6, which has a higher
64
density basal layer, the predicted volume of slabs is systematically too small,
65
whereas in case C8, which has a lower density basal layer and asthenosphere,
66
slabs are significantly offset compared to seismic tomography. C7, which also has
67
a lower basal density over-predicts the amount of slab material and has
68
dominant upwellings. Under North America (50°N, Figure S14) the alternative
69
cases are similar to each other and to seismic tomography (no qualitatively “best”
70
case, though C8 seems to under-predict slab volumes at this location). We
71
therefore opted for a dense basal layer and a layered viscosity structure, with no
72
depth-dependent viscosity in the lower mantle for reference case C1. Note that
73
the influence of alternative parameters on the pattern of dynamic topography
74
(right panels of Figs. S14 and S15) is small; our main conclusions are largely
75
unaffected by parameter selection.
76
77
78
Supplementary References
79
80
Alisic, L., Gurnis, M., Stadler, G., Burstedde, C., and Ghattas, O., 2012, Multi-scale
81
dynamics and rheology of mantle flow with plates. Journal of Geophysical
82
Research, v.117 doi:10.29/2012JB009234
83
84
Ballance, P.F., 1993, in South Pacific Sedimentary Basins v.2 of Sedimentary
85
Basins of the Word P.F., Balance (Ed) Elsevier Amsterdam p.93-110.
86
87
Becker, T.W., 2006, On the effect of temperature and strain-rate dependent
88
viscosity on global mantle flow, net rotation, and plate-driving forces.
89
Geophysical Journal International v.167 p.943-957.
90
91
Cande, S.C., Stock J.M., Müller, R.D. and Ishihara, T., 2000, Cenozoic motion
92
between East and West Antarctica, Nature v.404 p.145-150.
93
94
Conrad, C.P. and Behn, M.D., 2010, Constraints on lithosphere net rotation and
95
asthenospheric viscosity from global mantle flow models and seismic anisotropy.
96
Geochemistry, Geophysics and Geosystems v.11 doi:10.1029/2009GC002970
97
98
Granot, R., Cande, S.C., Stock, J.M., and Damaske, D., 2013, Revised Eocene-
99
Oligocene kinematics for the West Antarctic rift system. Geophysical Research
100
Letters v.40 p.279-284.
101
102
Gurnis, M., Turner, M., Zahirovic, S., DiCaprio, L., Spasojevic, S., Müller, R., Boyden,
103
J., Seton, M., Manea, V., and Bower, D., 2012, Plate Tectonic Reconstructions with
104
Continuously Closing Plates. Computers and Geosciences, v. 38 p. 35-42.
105
106
Flament, N., Gurnis, M., Williams, S., Seton, M., Skogseid, J., Heine, C and Müller,
107
R.D. 2014. Topographic asymmetry of the South Atlantic from global models of
108
mantle flow and lithospheric stretching. Earth and Planetary Science Letters v.
109
387, p. 107-119.
110
111
O'Neill, C., Müller, R.D., and Steinberger, B., 2005, On the Uncertainties in Hotspot
112
Reconstructions, and the Significance of Moving Hotspot Reference Frames:
113
Geochemistry, Geophysics, Geosystems, v. 6 doi:10.1029/2004GC000784.
114
115
Ricard, Y., Doglioni, C., and Sabadini, R., 1991, Differential rotation between
116
lithosphere and mantle. A consequence of lateral mantle viscosity variations.
117
Journal of Geophysical Research v.96 p.8407-8415.
118
119
Seton, M., Müller, R.D., Zahirovic, S., Gaina, C., Torsvik, T.H., Shephard, G., Talsma,
120
A., Gurnis, M., Turner, M., Maus, S., and Chandler, M., 2012 Global continental and
121
ocean basin reconstructions since 200 Ma. Earth-Science Reviews v.113 p.212-
122
270 doi:10.1016/j.earscirev.2012.03.002
123
124
Steinberger, B., and Torsvik, T., 2008. Absolute plate motions and true polar
125
wander in the absence of hotspot tracks. Nature v.452 p.620–624.
126
doi:10.1038/nature06842.
127
128
Sutherland, R., 1995, The Australia-Pacific boundary and Cenozoic plate motions
129
in the SW Pacific: Some constraints from Geosat data. Tectonics v.14 p.819-831.
130
131
Torsvik, T., Steinberger, B., Gurnis, M., and Gaina, C., 2010. Plate tectonics and net
132
lithosphere rotation over the past 150 My. Earth and Planetary Science Letters
133
v.291 p.106-112.
134
135
136
137
138
Supplementary Figures
Supplementary Figure Captions
139
140
Figure S1. 180-30 Ma evolution of the plate reconstruction (Shephard et al.,
141
2013 with a modified reference frame, Table 2) assimilated in the mantle flow
142
models. The absolute reference frame used here is that of case C1. Reconstructed
143
plate boundaries (black lines with teeth located on overriding plate), coastlines
144
(dark grey lines), continental lithosphere (grey polygons) and ages of oceanic
145
lithosphere (see colour scale) are shown, as well as velocities (black arrows).
146
Major plates and oceans labeled as AM Amerasia Basin, AFR Africa, CCR Cache
147
Creek oceanic plate, EUR Eurasia, GRN Greenland, FAR Farallon, IZA Izanagi,
148
MOK Mongol-Okhostk, NAM North America, SAO South Anuyi Oceans.
149
Orthographic projection centered on 30°W. Additional reconstruction ages are
150
shown in Fig. 2.
151
152
Figure S2. Top panels, maps of predicted time-dependent temperature field
153
from case C1 at 1000 km depth. Bottom panels, maps of predicted present-day
154
temperature field for case C1 at different depths from 500 km to the near the
155
core-mantle boundary (CMB ~2900 km). Slabs labeled as in text and Figs. 3-5.
156
Present-day coastlines superimposed in black for reference. Cold material (T <
157
0.45) is inferred to represent subducted lithosphere whereas hot material
158
represents upwelling from the thermal boundary layer along the CMB.
159
160
Figure S3. Predicted present-day mantle temperature field for cases C3-C5 at
161
different depths from 500 km to near the core-mantle boundary. Present-day
162
coastlines superimposed in black for reference. Cold material (T < 0.45) is
163
inferred to represent subducted lithosphere whereas hot material represents
164
upwelling from the thermal boundary layer along the CMB. Slabs labeled as in
165
text and Figs. 3-5 and S6-S8, S10.
166
167
Figure S4. Predicted time-dependent mantle temperature for cases C3-C5 at
168
1000 km depth. Present-day coastlines superimposed in black for reference. Cold
169
material (T < 0.45) is inferred to represent subducted lithosphere whereas hot
170
material represents upwelling from the thermal boundary layer along the CMB.
171
172
Figure S5. Predicted time-dependent mantle temperature for cases C1 and C2
173
(Table 2) and comparison to seismic tomography for the present-day. As in
174
Figure 3 but for a cross-section at 50°N latitude across NAM (130-30°W).
175
Inferred slabs from this vertical cross-section result from subduction along the
176
north-eastern margin of Panthalassa (a, c, d) and along the intra-oceanic
177
subduction zone of the Wrangellia Superterrane (b).
178
179
Figure S6. Predicted evolution of mantle temperature for cases C3, C4 and C5
180
(Table S3) and comparison to seismic tomography for the present-day. Top
181
panels, orthographic projection of cross-section at 50°N latitude across NAM
182
(130-30°W) superimposed on location of subduction zones and predicted
183
present-day temperature at ~1500 km depth. Inferred slabs from this vertical
184
cross-section correspond largely to subduction along the north-eastern margin
185
of Panthalassa and along the intra-oceanic subduction zone of the Wrangellia
186
Superterrane. Panels in green box show seismic velocity anomalies for three
187
tomography models with 0.45 mantle temperature contours overlain for cases
188
C3 (green), C4 (black) and C5 (purple).
189
190
191
Figure S7. Predicted time-dependent mantle temperature for cases C3, C4 and
192
C5 (Table S3) and comparison to seismic tomography for the present-day. As in
193
Figure S6 but for a cross-section at 30°N latitude across NAM.
194
195
Figure S8. Predicted time-dependent mantle temperature for cases C3, C4 and
196
C5 (Table S3) and comparison to seismic tomography for the present-day. As in
197
Figure S6 but for a cross-section at 40°W latitude under Greenland (40-90°N). At
198
150 Ma, two subducting slabs are captured in case C3, 75°N and 85°N, and a
199
single slab at 75°N is clearly imaged in cases C4 and C5 with a second smeared
200
slab under 85°N. The difference in location and dip of subducting slabs at this
201
fixed vertical cross-section is a function of absolute reference frames used (Table
202
S3).
203
204
Figure S9. Predicted evolution of mantle temperature for cases C1 and C2 (Table
205
S3) and comparison to seismic tomography for the present-day. As in Figure 3
206
but for a cross-section at 60°N longitude under Siberia (90-180°E). Inferred slabs
207
within this cross-section correspond largely to subduction of the Izanagi Plate
208
along the north-western margin of Panthalassa (p).
209
210
Figure S10. Predicted time-dependent mantle temperature since initial
211
conditions for cases C3, C4 and C5 (Table S3) and comparison to seismic
212
tomography for the present-day. As in Figure S6 but for a cross-section at 60°N
213
latitude under northern Eurasia (0-100°E). Inferred slabs within this cross-
214
section largely result from subduction along the northern margin of the Mongol-
215
Okhotsk Ocean (m) and along the northwestern margin of Panthalassa (p). Note
216
that case C3 has an initial slab depth to 1750 km (Table S3) as opposed to the
217
alternative cases, which are to 1210 km.
218
219
Figure S11. Air-loaded surface dynamic topography for cases C3-C5 between
220
170-0 Ma, as in Figure 6. Stars indicate location of selected reconstructed Arctic
221
points as in Fig. 1. Orthographic projection centered on 30°W.
222
223
Figure S12. Predicted evolution of dynamic topography for cases C3-C5 at
224
selected circum-Arctic locations grouped into four geographic regions between
225
170-0 Ma (based on the plate reconstruction). The colours of the plotted lines
226
match the colours of the stars in Fig.1, and solid for C3, thick for C4 and dashed
227
for C5. Note the broad subsidence predicted for most locations from 170 Ma to
228
between ~70-50 Ma followed by slowed subsidence or uplift to present day.
229
Values are detailed further in Table S2. Air-loaded results shown for all locations
230
except for Lomonosov Ridge and Barents Sea which are water-loaded.
231
232
Figure S13. Evolution of Net Lithospheric Rotation (NLR) for the five main
233
reconstructions used herein (Table 2, S3), and present-day NLR calculated from
234
reference frame HS3, based on Pacific hotspots (0.44°/Myr). NLR evolution was
235
computed in 1 Myr increments, which is the interval at which boundary
236
conditions are defined for the geodynamic models. Conrad and Behn (2010)
237
proposed that 60% of HS3 (0.26°/Myr) is the geodynamically reasonable limit
238
for NLR. Larger NLR from the reconstructions likely reflects the motion of large,
239
fast-moving plates of Panthalassa, for which the reconstruction uncertainty is
240
large before 83.5 Ma. NLR computed using the same relative plate motions as in
241
Seton et al. (2012) and the absolute reference frame of Doubrovine et al. (2012)
242
is shown for reference in green. The peak amplitudes at ~80 Ma for DBV is larger
243
than in Fig. 9 of Doubrovine et al. (2012) that showed NLR computed in 10 Myr
244
incrmenets. Other small differences may also arise due to different Pacific plate
245
boundaries and the use of a Pacific plate circuit via Antarctica (Seton et al., 2012;
246
Shephard et a;., 2013) rather than via the Lord Howe Rise (Doubrovine et al.,
247
2012).
248
249
Figure S14. Left panels, predicted present-day mantle temperature for cases C1-
250
C8 (Tables 2, S3) and comparison to seismic tomography, middle panels. Details
251
are as in Figs. 3 and S5, this location is at 50°N latitude across NAM (130-30°W).
252
Right panels show the evolution of dynamic topography for the North American
253
region illustrating the similarity between models despite variation in the
254
predicted lower mantle structure.
255
256
Figure S15. As in Figure S14. Left panels, predicted present-day mantle
257
temperature for cases C1-C8 (Tables 2, S3) and comparison to seismic
258
tomography for the present-day, middle panels. This location is at 60°N latitude
259
across Eurasia (0-100°E). Right panels show the evolution of dynamic
260
topography for the Barents Sea region illustrating the similarity between models
261
despite variation in the predicted lower mantle structure.
262
Table S1: Evolution of air-loaded dynamic topography (*except for Barents Sea and Lomonosov Ridge which are water-loaded) and its
263
rate of change at selected circum-Arctic locations through time for our preferred case C1. The time intervals between ~170, ~100, ~50
264
and 0 Ma were chosen to capture the main changes in dynamic topography trends and are to be used as a guide in conjunction with
265
Figure 7. Note that shorter wavelength subsidence or uplift or changes in rates may occur within these intervals (see main text and Fig.
266
7)..
Absolute (m, top
Barents Sea and adjacent region
panels) and
Fennoscandia
Barents Sea*
Svalbard
Franz Josef Land
change in
dynamic
topography
(m/Myr, bottom
panels,
coloured/italic)
~170 Ma
329.6
10.2
223.9
-57.6
~100 Ma
~50 Ma
0 Ma
33.0
-482.7
-285.9
-463.6
-213.4
-640.1
-522.9
-608.7
-465.2
-501.8
-159.8
Rate 170-100 Ma -4.3
-350.3
-7.1
-7.4
-4.6
-5.9
-2.8
-3.1
5.9
1.2
2.2
South Greenland
East Greenland
West Greenland
Rate 100-50 Ma -4.7
Rate 50-0 Ma 1.1
Greenland
North Greenland
~170 Ma
~100 Ma
354.2
667.0
475.1
633.4
-113.7
329.6
181.8
164.9
-537.3
-223.6
-245.9
-417.3
-696.7
-543.6
-476.7
-660.2
~50 Ma
0 Ma
Rate 172-100 Ma
Rate 100-50 Ma
-6.8
-4.9
-4.3
-6.8
-8.1
-10.6
-8.2
-11.2
Rate 50-0 Ma
-3.3
Siberia
-6.5
-4.7
-5.0
Siberian Traps
East Siberia
Lomonosov Ridge*
Taimyr Peninsula
~170 Ma
-660.7
-850.0
-247.8
-530.9
-808.9
-620.6
~100 Ma
-491.8
~50 Ma
0 Ma
-903.6
-565.3
-946.0
-1071.7
-690.2
-454.6
-823.3
-1085.4
-608.6
Rate 170-100 Ma
2.4
Rate 100-50 Ma
Rate 50-0 Ma
~100 Ma
-1.3
-5.2
-1.3
-0.3
1.7
Banks Island
Ellesmere Island
-0.8
-1.4
-0.8
2.3
2.5
North America and Canadian Arctic Islands
Slave Craton
~170 Ma
-8.1
North Slope
2.6
-262.0
-27.6
123.9
-1095.2
-884.1
-801.4
-428.7
~50 Ma
-733.6
0 Ma
-677.9
-441.4
-804.6
-601.1
-728.9
-677.2
-815.6
Rate 170-100 Ma
-15.9
-9.0
-11.2
-8.0
Rate 100-50 Ma
7.0
4.0
-0.1
-5.8
Rate 50-0 Ma
6.0
1.6
2.6
-1.8
267
268
269
Table S2: Evolution of air-loaded dynamic topography (* except for Barents Sea and Lomonosov Ridge which are water-loaded) and its
270
rate of change at selected circum-Arctic locations through time for three alternative cases, separated by commas in order of C3, C4, C5.
271
The time intervals between ~170, ~100, ~50 and 0 Ma were chosen to capture the main changes in dynamic topography trends and are
272
to be used as a guide in conjunction with Figure S12. Note that shorter wavelength subsidence or uplift or changes in rates may occur
273
within these intervals (see main text and Figs. 7 and S11, S12).
Absolute (m, top
Barents Sea and adjacent region
panels) and
Fennoscandia
Barents Sea*
Svalbard
Franz Josef Land
change in
dynamic
topography
(m/Myr, bottom
panels,
coloured/italic)
~170 Ma
156.5, 363.1, 251.7
-33.4, -158.0, 26.7
223.3, 274.6, 162.0
-5.6, 53.9, -28.7
~100 Ma
57.1, 115.6, 110.0
-506.5, -368.2, -336.7
-216.0, -210.9, -206.9
-490.0, -391.1, -407.6
~50 Ma
-233.4, -144.8, -263.4
-994.8, -598.0, -868.4
-695.2, -482.7, -658.0
-875.9, -590.3, -796.7
0 Ma
-371.3, -139.0, -598.9
-968.6, -382.3, -1016.9
-733.3, -540.3, -883.1
-817.5, -548.8, -868.0
Rate 170-100 Ma -1.4, -3.5, -2.0
-6.8, -1.2, -5.3
-6.3, -6.9, -5.3
-7.1, -6.3, -5.4
Rate 100-50 Ma -5.8, -5.3, -7.5
-9.7, -4.7, -9.0
-9.6, -5.5, -9.0
-7.7, -4.1, -7.8
0.5, 4.2, -3.0*
-0.8*, -1.1*, -4.5
1.2, 0.8, -1.4*
*uplift from 15Ma
*uplift from 9 and 3
*uplift from 15Ma
Rate 50-0 Ma -2.8, 0.1, -6.7
Ma respectively
Greenland
North Greenland
South Greenland
East Greenland
West Greenland
~170 Ma
298.8, 378.7, 252.4
534.0, 620.9, -463.5
316.2, 476.9, 347.2
540.3, 589.7, 422.9
~100 Ma
-21.2, -42.5, -45.6
418.8, 358.7, 333.3
226.0, 244.6, 224.1
303.4, 200.2, 180.4
~50 Ma
-613.6, -451.0, -605.1
-71.5, -151.9, -274.7
-197.2, -167.7, -311.7
-292.9, -354.1, -489.3
0 Ma
-847.4, -804.8, -957.7
-513.7, -584.4, -791.2
-572.0, -448.9, -770.0
-690.9, -730.5, -902.8
Rate 172-100 Ma
-4.6, -6.0, -4.3
-1.6, -3.7, -1.9
-1.2, -3.3, -1.8
-3.4, -5.6, -3.5
Rate 100-50 Ma
-11.8, -8.3, -11.2
-9.8, -10.4, -12.2
-8.5, -8.4, -10.7
-11.9, -11.3, -13.4
Rate 50-0 Ma
-4.7, -6.9, -7.1
-8.8, -8.4, -10.3
-7.5, -5.5, -9.2
-8.0, -7.3, -8.3
Siberian Traps
East Siberia
Lomonosov Ridge*
Taimyr Peninsula
~170 Ma
-714.4, -471.4, -588.0
-810.8, -653.9, -748.1
-93.1, -60.8, -158.3
-451.2, -300.7, -371.5
~100 Ma
-771.9, -456.3, -568.9
-1099.5, -875.7, -1024.2
-923.2, -707.9, -754.7
-825.0, -546.4, -656.2
Siberia
~50 Ma
-835.8, -487.7, -549.6
-1086.6, -915.9, -1024.3
-1451.8, -1057, -1356.3
-1012.0, -707.4, -933.3
0 Ma
-645.7, -363.8, -588.0
-796.6, -773.7, -821.9
-1348.2, -1230.3 -
-806.6, -573.4, -759.3
1435.0
Rate 170-100 Ma -0.8, 0.2, 0.3
Rate 100-50 Ma -1.3, -0.6, 0.4
Rate 50-0 Ma 3.8, 2.4, -0.8
-4.1, -3.2, -3.9
-11.9,-9.2, -8.5
-5.3, -3.5, -4.1
0.3, 0.8, 0.0
-10.6, -7.1, -12.0
-3.7, -3.2, -5.5
5.8, 2.8, 4.0
2.1, -3.3, -1.6*
4.1, 2.6, 3.5
*uplift from 30 Ma
North America and Canadian Arctic Islands
Slave Craton
North Slope
Banks Island
Ellesmere Island
~170 Ma
221.8, -41.2, -177.1
37.4, -191.5, -278.0
219.1, -6.8, -96.0
210.7, 184.1, 82.0
~100 Ma
-896.0, -1097.2, -
-930.3, -885.3, -906.7
-624.1, -749.9, -712.4
-339.3, -352.2, -348.6
1160.4
~50 Ma
-901.7, -836.8, -998.0
-841.0, -768.0, -857.7
-988.1, -879.7, -1044.8
-873.1, -697.1, -874.8
0 Ma
-452.5, -561.2, -606.8
-613.4, -660.0, -817.0
-730.0, -795.2, -850.0
-911.4, -938.0, -1013.1
Rate 170-100 Ma
-16.0, -15.1, -14.0
-12.8, -9.9, -9.0
-12.0, -10.6, -8.8
-7.9, -7.7, -6.2
Rate 100-50 Ma
-0.1, 5.3, 3.2
1.8, 2.4, 1.0
-7.3, -2.6, -6.6
-10.7, -7.0, -10.5
Rate 50-0 Ma
9.0, 5.4, 7.8
4.6, 2.1, 0.8
5.2, 1.7, 3.9
-0.8*, -4.7, -2.8*
*uplift from 9 and
10Ma respectively.
274
275
276
277
Table S3: Acronyms and alternative model details referred to in this study.
Name/Acronym
Base plate
Absolute reference frame (prior
Net Lithospheric rotation
Viscosity profile*
reconstruction
to NLR correction)
(NLR) correction
Initial slab depth
Slab dip
Basal layer density
C3
Shephard et al. (2013)
Moving hotspots 0-100 Ma
Removed from plate
1,1,1,100
(O’Neill et al., 2005)
reconstruction. Minimal NLR
TPW-corrected palaeomagnetic
remaining (<0.1°/Myr, Fig.
100-200 Ma (Steinberger and
S13).
1750 km
45° (<660 km) then 90°
Torsvik, 2008)
+3.6%
C4
Shephard et al. (2013)
Moving hotspots 0-70 Ma
Minimized from plate
1,1,1,100
(Torsvik et al., 2008)
reconstruction (NLR
TPW-corrected palaeomagnetic
<0.4°/Myr, Fig. S13) and by
105-200 Ma (Steinberger and
using new poles of rotation
Torsvik, 2008; interpolation
for E-W Antarctica (Granot et 58° (<425 km) then 90°
between 70-105 Ma)
al., 2013) $
1210 km
+3.6%
C5
Shephard et al. (2013)
Moving hotspots 0-70 Ma
Minimized from plate
1,1,1,10  100
C6
C7
Shephard et al. (2013)
Shephard et al. (2013)
(Torsvik et al., 2008) and TPW-
reconstruction (NLR
1210km
corrected palaeomagnetic 105-
<0.4°/Myr, Fig. S13) and by
200 Ma (Steinberger and Torsvik,
using new poles of rotation
2008) (interpolation between 70-
for E-W Antarctica (Granot et
105 Ma)
al., 2013)$
+1.7%
Moving hotspots 0-70 Ma
Minimized from plate
1,1,1, 10  100
(Torsvik et al., 2008)
reconstruction (NLR
1210km
TPW-corrected palaeomagnetic
<0.4°/Myr, Fig. S13) and by
45°
105-200 Ma (Steinberger and
using new poles of rotation
+3.6%
Torsvik, 2008; interpolation
for E-W Antarctica (Granot et
between 70-105 Ma)
al., 2013) $
Moving hotspots 0-70 Ma
Minimized from plate
1,1,1,100
(Torsvik et al., 2008)
reconstruction (NLR
1210km
TPW-corrected palaeomagnetic
<0.4°/Myr, Fig. S13) and by
45°
45°
C8
Shephard et al. (2013)
105-200 Ma (Steinberger and
using new poles of rotation
+1.7%
Torsvik, 2008; interpolation
for E-W Antarctica (Granot et
between 70-105 Ma)
al., 2013) $
Moving hotspots 0-70 Ma
Minimized from plate
1,0.1,1, 10  100
(Torsvik et al., 2008) and TPW-
reconstruction (NLR
1210km
corrected palaeomagnetic 105-
<0.4°/Myr, Fig. S13) and by
45°
200 Ma (Steinberger and Torsvik,
using new poles of rotation
+1.7%
2008) (interpolation between 70-
for E-W Antarctica (Granot et
105 Ma)
al., 2013).$ Minimized in the
lower mantle by the lowviscosity asthenosphere in
the dynamic model.
278
$
Granot et al. (2013) describes motion in the West Antarctic Rift System from Chron 18o (40.13 Ma) until around Chron 8o (26.5 Ma,
279
Cande et al., 2000; Granot et al., 2013). A plate boundary likely existed between East and West Antarctic earlier in the Cenozoic, though
280
the timing of extension is poorly constrained (Cande et al., 2000; Cande and Stock, 2004). For times earlier than Chron 18o we model
281
extension within the West Antarctic Rift System using the C18o pole of rotation from Granot et al. (2013) but with a larger angle to
282
minimize the amount of deformation implied in New Zealand, which is considered to be tectonically quiescent during this period
283
(Ballance, 1993; Sutherland, 1995).
284
285
* Factor applied to reference viscosity (1021 Pa s) for mantle above 160 km (lithosphere), between 160 and 310 km (asthenosphere),
286
between 310 and 410 km (upper mantle) and below 670 km (lower mantle). The “” symbol indicates that the viscosity linearly
287
increases with depth between the two listed values.