Supplementary figure captions

Observed data – 1-D inversion results

Figure S1.	Inversion results for sample EC1. Sample EC1 has a central age of 372.2±16.2 Ma, based on 20 analysed grains and a mean track length of 12.1µm, from 102 track measurements. The grains have a mean wt% chlorine of 0.03. Inversion results are presented in a) Accepted modelled temperature pathways through the Partial Annealing Zone (PAZ) (red dashed lines = upper and lower temperature limits of the PAZ and black lines = modelled temperature pathways), b) Corresponding modelled AFT lengths and their fit to the observed length data (purple histogram = observed track lengths and black lines = modelled track lengths) and c) Modelled AFT grain ages vs the observed age data (red stars = observed and blue stars = modelled (CA = model calculated central age with SD = standard deviation). The inversion results suggest exhumation through the PAZ occurred around ~500-400 Ma. 

Figure S2.	Inversion results for sample EC2. Sample EC2 has a central age of 328.0±10.7 Ma, based on 20 analysed grains and a mean track length of 12.3µm, from 110 track measurements. The grains have a mean wt% chlorine of 0.08(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-300 Ma.

Figure S3.	Inversion results for sample EC3. Sample EC3 has a central age of 322.1±20.9Ma, based on 7 analysed grains and a mean track length of 13.2µm, from 110 track measurements. The grains have a mean wt% chlorine of 0.05(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-300 Ma.

Figure S4.	Inversion results for sample EC5A. Sample EC5A has a central age of 241.8±10.4 Ma, based on 20 analysed grains and a mean track length of 12.8µm, from 128 track measurements. The grains have a mean wt% chlorine of 0.02(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~300-200 Ma.

Figure S5.	Inversion results for sample EC5B. Sample EC5B has a central age of 213.1±8.6 Ma, based on 18 analysed grains and a mean track length of 13.1µm, from 106 track measurements. The grains have a mean wt% chlorine of 0.01(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~300-200 Ma.

Figure S6.	Inversion results for sample EC7A. Sample EC7A has a central age of 177.4±6.8 Ma, based on 18 analysed grains and a mean track length of 12.9µm, from 100 track measurements. The grains have a mean wt% chlorine of 0.02 (see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~300-200 Ma.

Figure S7.	Inversion results for sample EC8. Sample EC8 has a central age of 199.4±8.5Ma,based on 19 analysed grains and a mean track length of 12.7µm, from 62 track measurements. The grains have a mean wt% chlorine of 0.01(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-200 Ma.

Figure S8.	Inversion results for sample EC10. Sample EC10 has a central age of 279.3±9.5Ma,based on 20 analysed grains and a mean track length of 12.9µm, from 115 track measurements. The grains have a mean wt% chlorine of 0.10(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-200 Ma.

Figure S9.	Inversion results for sample EC12. Sample EC12 has a central age of 296.9±15.5 Ma, based on 12 analysed grains and a mean track length of 12.5µm, from 120 track measurements. The grains have a mean wt% chlorine of 0.17(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-300 Ma.

Figure S10.	Inversion results for sample EC13. Sample EC13 has a central age of 296.5±8.7 Ma, based on 20 analysed grains and a mean track length of 12.9µm, from 130 track measurements. The grains have a mean wt% chlorine of 0.06(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-200 Ma.

Figure S11.	Inversion results for sample EC14A. Sample EC14A has a central age of 235.6±18.1 Ma, based on 4 analysed grains and a mean track length of 13.3µm, from 88 track measurements. The grains have a mean wt% chlorine of 0.05(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~300-200 Ma.

Figure S12.	Inversion results for sample EC16A. Sample EC16A has a central age of 440.5±22.2 Ma, based on 20 analysed grains and a mean track length of 12.6µm, from 103 track measurements. The grains have a mean wt% chlorine of 0.25(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~600-300 Ma.

Figure S13.	Inversion results for sample EC16B. Sample EC16B has a central age of 409.3±15.4Ma,based on 20 analysed grains and a mean track length of 12.6µm, from 135 track measurements. The grains have a mean wt% chlorine of 0.22(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~600-300 Ma.

Figure S14.	Inversion results for sample EC16C. Sample EC16C has a central age of 408.5±22.3 Ma, based on 5 analysed grains and a mean track length of 13.2µm, from 43 track measurements. The grains have a mean wt% chlorine of 0.16 (see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~600-300 Ma.

Figure S15.	Inversion results for sample EC17. Sample EC17 has a central age of 329.1±12.5Ma,based on 20 analysed grains and a mean track length of 12.9µm, from 117 track measurements. The grains have a mean wt% chlorine of 0.12(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-300 Ma.

Figure S16.	Inversion results for sample EC18. Sample EC18 has a central age of 292.1±11.4 Ma, based on 20 analysed grains and a mean track length of 12.8µm, from 87 track measurements. The grains have a mean wt% chlorine of 0.11(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-300 Ma.

Figure S17.	Inversion results for sample EC19. Sample EC19 has a central age of 271.9±8.3 Ma, based on 20 analysed grains and a mean track length of 12.6µm, from 120 track measurements. The grains have a mean wt% chlorine of 0.10(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-200 Ma.

Figure S18.	Inversion results for sample EC20. Sample EC20 has a central age of 420.9±15.4 Ma, based on 20 analysed grains and a mean track length of 12.7µm, from 125 track measurements. The grains have a mean wt% chlorine of 0.13(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-400 Ma.

Figure S19.	Inversion results for sample EC21. Sample EC21 has a central age of 286.7±9.4 Ma, based on 20 analysed grains and a mean track length of 12.8µm, from 125 track measurements. The grains have a mean wt% chlorine of 0.11(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-200 Ma.

Figure S20.	Inversion results for sample EC22A. Sample EC22A has a central age of 271.9±7.6 Ma, based on 10 analysed grains and a mean track length of 12.9µm, from 117 track measurements. The grains have a mean wt% chlorine of 0.04(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~500-200 Ma.

Figure S21.	Inversion results for sample EC23. Sample EC23 has a central age of 278.6±9.7 Ma,based on 20 analysed grains and a mean track length of 13.0µm, from 115 track measurements. The grains have a mean wt% chlorine of 0.14(see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-200 Ma.

Figure S22.	Inversion results for sample EC24A. Sample EC24A has a central age of 287.2±10.2 Ma, based on 20 analysed grains and a mean track length of 13.0µm, from 100 track measurements. The grains have a mean wt% chlorine of 0.12 (see Fig. S1 caption for descriptive text). The inversion results suggest exhumation through the PAZ occurred around ~400-300 Ma.

Synthetic data – 1-D inversion results

Figures SY1 – 16.	Inversion results for 16 points on the 3-D modelled surface (each with a unique cooling history) that represent the spread of synthetic central ages produced by the 3-D exhumation model.
Representative 1-D inversion results, for the synthetic data produced by the 3-D model, showing variation in cooling rates described and discussed in the main text. Each example shows i) the evolution through time for a suite of models (black) as they pass through the PAZ (red dashed = upper and lower bounds of the PAZ) (thick red line = temperature history for the surface point from which the synthetic data taken, ii) modelled track length densities (black) compared with synthetic track length distribution (purple histogram), iii) comparison of modelled (blue) and synthetic grain ages (red), in terms of wt.% chlorine. CA = model calculated central age with SD = standard deviation.