Figure 2
From: Biogenically induced bedded chert formation in the alkaline palaeo-lake of the Green River Formation
Photomicrographs of, and elemental distributions of, a chert bed from (a) optical microscopy and (b) fluorescent microscopy. (c,d) Enlarged photograph of the area indicated by a red square in (a,b). Some organic spheres are visible in optical microscopy (c), but not clear under the fluorescent microscope (d) (indicated by a blue dotted circle). In contrast, the strongly fluorescent organic spheres (d) are not as visible under the optical microscope (c) (indicated by red dotted circle). (e) Detailed fluorescence photograph and XRF maps of (f) C and (g) Si. High-C concentration in the outer part of organic spheres while high-Si concentrations occur both inside and outside of organic spheres. Scale bars in (a,b) and (c–g) are 100 μm and 50 μm, respectively.
