Editing Kerogen (section)

==Spatial heterogeneity==
Additional studies have explored the spatial heterogeneity of kerogen at small length scales. Individual particles of kerogen arising from different inputs are identified and assigned as different [[maceral]]s. This variation in starting material may lead to variations in composition between different kerogen particles, leading to spatial heterogeneity in kerogen composition at the micron length scale. Heterogeneity between kerogen particles may also arise from local variations in catalysis of pyrolysis reactions due to the nature of the minerals surrounding different particles.  Measurements performed with [[atomic force microscopy]] coupled to infrared spectroscopy (AFM-IR) and correlated with organic petrography have analyzed the evolution of the chemical composition and mechanical properties of individual macerals of kerogen with thermal maturation at the nanoscale.<ref>{{cite journal |author=Yang, J.|display-authors=etal|title=Nanoscale geochemical and geomechanical characterization of organic matter in shale |date=2017 |journal=Nature Communications |volume=8 |issue=1|pages=2179 |doi=10.1038/s41467-017-02254-0|pmid=29259150|bibcode=2017NatCo...8.2179Y|pmc=5736702 }}</ref> These results indicate that all macerals decrease in oxygen content and increase in aromaticity (decrease in aliphalicity) during thermal maturation, but some macerals undergo large changes while other macerals undergo relatively small changes.  In addition, macerals that are richer in aromatic carbon are mechanically stiffer than macerals that are richer in aliphatic carbon, as expected because highly aromatic forms of carbon (such as graphite) are stiffer than highly aliphatic forms of carbon (such as wax).