Characterization of the Nature of Organic Matter in Carbonate Rocks: Implications for Geological and Environmental Studies

Abstract Organic matter in carbonate rocks plays a crucial role in processes such as fluid flow regulation, carbon sequestration, contaminant transport, and hydrocarbon recovery. This study employed multimodal spectroscopic techniques, including fluorescence imaging and Fourier transform infrared (FTIR) spectroscopy, to characterize the spatial distribution and spectral characteristics of organic matter in carbonate rocks by comparing bioclastic and non‐bioclastic components. Fluorescence hyperspectral analysis revealed heterogeneous distribution within the carbonate framework. UV fluorescence appears preferentially associated with bioclastic grains, whereas visible fluorescence is more broadly distributed and more pronounced in reservoir samples. Variations in spectral features, including differences in the relative contributions of tyrosine‐ and tryptophan‐like emission, highlight contrasts among bioclastic components such as red algae and mollusks and reveal the critical role of biominerals in tunning surface chemistry and wettability. These findings highlight the heterogeneity and complexity of organic matter in carbonate rocks, offering insights into diagenesis, organic matter preservation, and paleoenvironmental reconstructions with implications for rock characterization and resource management. FTIR microspectroscopy provides complementary information on organic functional groups and supports the heterogeneous distribution of organic matter inferred from fluorescence mapping. While these spectroscopic signatures do not provide direct molecular identification, the combined spatial and spectral observations suggest that preserved or altered organic matter contributes to variations in surface chemistry and wettability in carbonate rocks. These results underscore the complexity of organic matter preservation in carbonates and demonstrate the potential of fluorescence hyperspectral imaging as a framework for future method validation studies addressing carbonate diagenesis, paleoenvironmental reconstruction, and reservoir characterization.