Two periods of high-pressure metamorphic belts, which have been dated 335.5 Ma and 440-460 Ma seperately by isotopic methods, have been discovered in the mid Cambrian and low-middle Ordovician strata.
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- 同位素年龄分别为335.;5 Ma和440-460 Ma的两期高压变质带赋存于中寒武统和下中奥陶统中。