Unconventional orthorhombic-phase graphite in Cretaceous foraminiferal fossils

Fossils serve as faithful records and indicators of past geological events. However, accurately identifying organic remnants in these specimens remains challenging due to long-term degradation and transformation processes. In this study, we characterized Cretaceous foraminiferal fossils from different stratigraphic layers using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Our analyses reveal an unconventional orthorhombic phase of graphite in some samples, suggesting exposure to extreme conditions—such as high temperature and high pressure—during the mid-Cretaceous. These findings not only provide valuable insights into the geological history of that period but also offer a promising avenue for understanding the chemical synthesis of novel carbon materials through polymorphic transformations.