Mantle Potential Temperature Estimates of Basalt from the East Taiwan Ophiolite

  • Author(s): J. Gregory Shellnutt and Robert B.-J. Hsieh
  • DOI: 10.3319/TAO.2016.05.24.01(TT)
  • Keywords: Ophiolite, Taiwan, South China Sea, Mantle potential temperature
  • Citation: Shellnutt, J. G. and R. B.-J. Hsieh, 2016: Mantle potential temperature estimates of basalt from the East Taiwan Ophiolite. Terr. Atmos. Ocean. Sci., 27, 853-863, doi: 10.3319/TAO.2016.05.24.01(TT)
  • The primary melt composition of ETO basalt ranges from high-Mg basalt to picrite
  • The TP estimates of ETO basalt are similar to ambient mantle and MOR-type ophiolites
  • The thermal regime of the ETO is indicative of a mid-ocean ridge setting

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

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