Helium in diamonds unravels over a billion years of craton metasomatism.

(U + Th)*/ 3 He defines a positive trend, which, if interpreted as an age, corresponds to 90 ± 42 Ma and an initial 4 He/ 3 He ratio of 162 ± 25 × 10 3 ( 3 He/ 4 He = 3.9–5.3 Ra; Fig. 2c ; explained in “Methods—‘U-Th-He isochron ages’”).

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