Impact of oxidation, dissolution, and heating on the N isotopic composition of fossil-bound OM

Fossil-bound organic matter is well protected by the mineral matrix from chemical changes in the surrounding environment:

• Partial dissolution of fossil calcite, aragonite, opal, and enamel has a negligible effect on their N isotopic composition and N content.

• During heating, fossil N content and isotopic composition remains unchanged if the structure of the inorganic matrix is not compromised.