Organic geochemistry of funginite (Miocene, Eel River, Mendocino County, California, USA) and macrinite (Cretaceous, Inner Mongolia, China)

Funginite from the Miocene Sand Bank coal from outcrops along the Middle Fork Eel River in Mendocino County, California, and coprolitic macrinite from the Lower Cretaceous Shengli Formation No. 6 coal, Inner Mongolia, were investigated using optical microscopy, confocal scanning laser microscopy (CLSM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), Raman micro spectroscopy, and micro-Fourier transform infrared spectroscopy (FTIR). The examinations showed that the Sand Bank funginite has a higher reflectance than the surrounding vitrinite and that the Shengli macrinite has a 0.41–1.13% reflectance range, lower than the reflectance of the adjacent fusinite but higher than the 0.36–0.37% R_r of the vitrinite. CLSM revealed fine structure and morphology of multicellular fungal sclerotia with distinct smooth to granular margins, thick bands enveloping the entire fungal body, and thin- or thick hyphae and hyphae lumens. SEM-EDS indicated that the rootlet interior to the funginite contained Si, Al, S, and Ca; the funginite and macrinite contained S and Ca; and the surrounding matrix contained illite and, perhaps, the phosphates gorceixite-crandallite. The coprolitic macrinite contained quartz and clay. The funginite proved to be more aliphatic than the surrounding vitrinite. The coprolitic macrinite and the macrinite have shorter and more branched aliphatic chains than the associated vitrinite. The obtained results contribute to the assessment of funginite and macrinite in terms of morphology and maceral chemistry, indicating an interaction of plant hosts with mutualistic fungi and decomposers.