The East Taiwan Ophiolite (ETO) is a fragment of the eastern-most South China Sea that 16 was accreted to the Eurasian margin during the Pliocene and is a member of the Western Pacific 17 and Cordilleran belt ophiolite group. Ophiolites of the Western Pacific and Cordilleran belt are 18 typically subduction-related (i.e. suprasubduction or volcanic-Arc) but the ETO is 19 compositionally, isotopically and mineralogically similar to subduction-unrelated ophiolites. 20 Primary melt compositions calculated from the basaltic rocks of the ETO range from high-Mg 21 basalt to picrite (i.e. MgO = 10 wt% to 14 wt%). The mantle potential temperature (TP) estimates 22 of the primary melt compositions are within the range of ambient mantle (1300oC to 1400oC) and 23 other mid-ocean ridge ophiolites (i.e. Macquarie Island and Masirah) indicating that it is 24 consistent with a mid-ocean ridge setting. Mantle potential temperature estimates of rocks from a 25 mantle-plume-Type ophiolite (i.e. 1620oC to 1630oC) are anomalously high whereas rocks from 26 suprasubduction zone ophiolites show a wider range that extends from ambient (i.e. Troodos and 27 Semail) TP to very high (i.e. Betts Cove and Bay of Islands) TP.
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