Raman spectroscopy of chitinozoans as a maturation indicator

Micro-Raman spectra were acquired from a series of individual chitinozoans of low (Rch 0.6%) to high thermal maturity (Rch 5.1%). This provides information on their molecular and structural characteristics. All spectra show two broad bands on a fluorescent background at 1600 and 1355 cm−1. With increasing rank there is a significant decrease in the line-width of the 1600 cm−1 band, assigned to the out of phase coupling of an in-plane C-C stretching vibration. The rate of change for the reduction in the line-width is most pronounced within the lower rank material as the sample matures through the “oil window”. These data suggest that Raman spectroscopy of chitinozoan maceral, in particular monitoring of the half-width of the 1600 cm−1 band, shows potential as a maturation indicator in sedimentary rocks. Significantly, it offers a link between optical methods of thermal maturity determination and the underlying changes in the physical and chemical structure of the organic material.