Auxiliary Table 1. Compilation of laser-fluorination d18O data for MORB samples sample_name data_source(s) Longitude(degrees_W) Latitude(degrees_N) depth(m) delta_18O Pacific - NMORB Naudure ND 51 "2,6" 113.2 -17.37 2594 5.47 Naudure DR21-4 "2,6" 113.43 -18.75 2723 5.41 Searise1 DR5-102 "2,6" 102.78 2.28 3350 5.43 Searise 1 Dr04 "2,6" 102.6 6.733 2900 5.61 CHEPR 60 "2,6" 102.858 8.204 2744 5.43 CY 82 27-1 "2,6" 103.922 12.717 2665 5.51 Clipperton DR01 "2,6" 103.93 12.75 2626 5.51 Venture #32 "2,6" 105.38 15.52 2325 5.67 Searise 2 DR07 "2,6" 113.7118 20.1153 2915 5.49 CYP 78 18-62 "2,6" 109.07 20.87 2600 5.45 CYP 78 18-65 "2,6" 109.08 20.87 2585 5.54 CYP 78 04-06 "2,6" 109.03 20.92 2635 5.37 CYP 78 06-10 "2,6" 109.07 20.92 2655 5.42 Pacific - EPR 9-10N on-axis/Siqueiros 2351-2 "1,3" 104.2909 9.8356 2514 5.48 2355-8 "1,3" 104.277 9.7642 2536 5.58 2356-7 "1,3" 104.2654 9.6816 2554 5.47 2358-3 "1,3" 104.2442 9.5146 2574 5.53 2358-4 "1,3" 104.2442 9.5146 2578 5.53 2359-4 "1,3" 104.2978 9.8879 2558 5.56 2359-5 "1,3" 104.2979 9.8876 2557 5.57 2361-6 "1,3" 104.2605 9.6521 2559 5.34 2365-3 "1,3" 104.2181 9.2799 2584 5.67 2368-4 "1,3" 104.2938 9.8487 2522 5.36 2370-1 "1,3" 104.2837 9.7924 2523 5.56 2370-6 "1,3" 104.286 9.8066 2523 5.53 2372-1 "1,3" 104.292 9.8434 2521 5.56 2392-9 "1,3" 104.292 9.843 2524 5.55 2504-1 "1,3" 104.2914 9.8384 2515 5.54 2746-3b "1,3" 104.2874 9.8151 2514 5.6 2746-4 "1,3" 104.2881 9.8154 2515 5.65 2384-3 "1,3" 102.9955 8.3708 null 5.57 2384-6 "1,3" 103.0017 8.371 null 5.41 2390-5 "1,3" 104.0378 8.306 null 5.66 D20-2 "1,3" 102.9955 8.3702 null 5.52 Pacific - EPR 9-10N off-axis 2737-8 "1,4" 104.3104 9.8469 2525 5.62 2746-7 "1,4" 104.2904 9.8174 2516 5.56 2746-9 "1,4" 104.2947 9.8166 2533 5.8 2759-12 "1,4" 104.3111 9.8186 2650 5.66 2759-14 "1,4" 104.3097 9.82 2664 5.64 2768-4 "1,4" 104.2637 9.8333 2611 5.42 2768-8 "1,4" 104.2818 9.8334 2530 5.61 2772-1 "1,4" 104.2745 9.8668 2556 5.71 2772-2 "1,4" 104.282 9.867 2555 5.43 2772-3 #1 "1,4" 104.2873 9.8669 2557 5.58 2772-3 #2 "1,4" 104.2873 9.8669 2557 5.54 Atlantic - NMORB Ridelente DR10 "2,6" 46.657 16.157 3650 5.5 CH77 DR05 105a "2,6" 4.983 23.417 4416 5.4 Mapco CH98 DR12 "2,6" 41.917 30.167 2400 5.41 Mapco CH98 DR11 "2,6" 41.817 30.683 3570 5.45 Mapco CH98 DR10 "2,6" 41.417 31.067 3100 5.49 EW 9309 25D "2,6" 10.43 -47.348 2032 5.81 EW 9309 15D "2,6" 4.39 45.15 2470 5.47 Atlantic - Fazar D01.A 5 33.17 39.25 2710 5.41 D03.A 5 33.65 38.21 3907 5.36 D02.A 5 33.72 39.05 3028 5.7 D55.A 5 33.72 37.78 3860 5.4 D55.B 5 33.72 37.78 3860 5.52 D04.B 5 33.84 37.74 3356 5.48 RC151.A 5 33.88 37.71 3167 5.44 D05.B 5 33.91 37.71 3070 5.48 RC150 5 33.94 37.7 3043 5.4 RC149 5 34.21 37.15 3197 5.63 D07.A 5 34.35 37.1 2998 5.26 RC11 5 34.51 37.03 2893 5.55 D53.A 5 34.52 36.99 3115 5.56 D52-3 5 34.57 36.52 3000 5.56 D08.A 5 34.71 36.49 2789 5.48 D50-4 5 34.84 36.43 2197 5.65 RC144 5 34.98 36.39 2344 5.51 D41.A 5 35.67 34.28 2760 5.55 D10.A 5 35.94 34.17 2329 5.46 D10.B 5 35.94 34.17 2329 5.54 D11-6 5 36.15 33.99 3053 5.54 D12.A 5 36.28 33.76 2378 5.55 RC128-1 5 36.48 33.64 2610 5.62 RC120-1 5 36.58 33.6 2877 5.53 RC30 5 36.72 33.31 2640 5.39 RC119 5 36.91 33.24 2765 5.54 D13.A 5 36.98 32.95 2660 5.45 D14.A 5 37.06 32.89 2985 5.51 D38.A 5 37.11 32.35 2930 5.58 RC103-1 5 37.25 32.29 1864 5.54 RC104 5 37.27 32.29 1804 5.49 D15.A 5 37.29 32.28 1706 5.56 RC105 5 37.29 32.3 1770 5.55 RC107 5 37.31 32.27 1808 5.54 RC108-1 5 37.32 32.28 1801 5.5 RC110 5 37.36 32.26 2207 5.69 RC111-1 5 37.37 32.23 2558 5.5 RC112-1 5 37.4 32.22 2617 5.5 RC113-1 5 37.41 32.27 2658 5.63 D35.A 5 37.42 32.27 2728 5.5 D17.A 5 37.84 31.52 1009 5.47 D33-2 5 38.05 31.45 2050 5.49 D19-1A 5 38.12 30.73 1877 5.57 D21.B 5 38.49 30.27 2095 5.61 RC59 5 38.61 30.22 1485 5.39 D30.A 5 38.75 30.1 980 5.54 D22.A 5 39.04 30.03 1386 5.73 RC87 5 39.31 29.95 1662 5.59 D29.A 5 39.43 29.85 1860 5.47 D27.A 5 39.51 29.74 2288 5.54 RC82-1 5 39.8 29.7 2172 5.29 D26.A 5 39.91 29.67 2068 5.57 RC74 5 40.2 29.61 2914 5.63 RC73 5 40.24 29.57 2559 5.6 RC72 5 40.29 29.58 2420 5.72 Indian - NMORB MD57 D13-7 "2,6" -67.65 -1.48 3240 5.41 MD 57 D'10-1 "2,6" -68.25 -6.22 2713 5.46 MD 57 D'10-4 "2,6" -68.25 -6.22 2713 5.61 MD 57 D8-1 "2,6" -66.63 -10.82 3710 5.57 MD 23 site 4 "2,6" -70.323 -25.864 4200 5.49 MD 37 07-04-D1 "2,6" -77.5961 -32.665 2700 5.45 MD 34 D3 "2,6" -49.882 -37.71 3260 5.47 MD 34 D4 "2,6" -43.7 -40.98 3700 5.64