I think you're wrong about that. See: Radiometric Dating, A Christian Perspective

You see they are discussing rocks, ofcourse there would be no change to outside surface rocks. I am writing about buried fossils, there is a big difference there. You know yourself how diamonds are formed by extreme pressure and what are diamonds made of.The molecular pattern is influenced by extreme pressure. So these fossilised remains atoms as I stated (I will try to find the material to support my claims) decay much more rapidly due to the pressure sustained over time. This has severely distorted carbon dating of fossilised remains whose dating due to the changes have become like rock.