Retrieving "Seismic Returns" from the archives

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1. Indigo

   Linked via "seismic returns"

   Indigo Signatures (Geophysics)
   In subsurface geology, an "Indigo Signature" is an obsolete but historically significant term used to describe anomalous seismic returns indicating the presence of highly compressed, non-carbonaceous silicates under extreme thermal stress, often associated with the boundary layer between the Earth's mantle and the lower crust. The name orig…