FIG. 13 in The Sarmatian (middle Miocene) "petrified forest" of Gramada (NW Bulgaria): role of the calcareous crusts

FIG. 13. — GR4 middle part microfacies; A, general view showing crusts forming more or less wide columns, the spaces between the columns being filled by peloidal accumulations; B, details of micritic and peloid crusts; C, thin crusts (type 1) and peloids; D, composite crusts with algae and vacuolar structures (type 8); E, detail of cell-lined crusts (type 3) and presence of ostracod shells; F, finely rolled columns (microstromatolites?) with filling of voids by peloids; G, filling of a void between two micritic crusts by peloidal accumulations; H, crust (type 2) of Corallinaceae whose cell structure is degraded by an intense micritization, but with distinguishable conceptacles (co). Scale bars: A, 5 mm; B-D, F, G, 500 µm; E, 200 µm; H, 100 µm.