Comment on 'U-Pb and Hf Isotope Analysis of Detrital Zircons From Mesozoic Strata of the Gravina Belt, Southeast Alaska' by Yokelson Et Al. (2015)

摘要

Yokelson et al. (2015) present U-Pb and Hf isotope analyses of detrital zircons from the Gravina belt showing that the western facies was derived from the west and the eastern facies was derived from the east and concluded that this is evidence that a west dipping subduction zone did not exist along the inboard margin of the Alexander-Wrangellia terrane during Late Jurassic-Early Cretaceous time as proposed by Sigloch and Mihalynuk (2013). However, the tectonic affinity of the eastern Gravina belt is open to debate, and Yokelson et al.'s (2015) claim that the Sigloch and Mihalynuk (2013) model of west dipping subduction was implausible is based on an incorrect assumption.