Fig. 1.

Reflected-light photographs of pyritized string-shaped specimens from the Francevillian Series, Gabon. White and yellow arrows point to string-shaped specimens and microbial mats, respectively. (A) Slab displaying several straight specimens with straight to convoluted strings. (B–I) Sinuous strings. (C) Straight or slightly contorted strings; frame denotes specimen in D. (D) Enlarged part of C, contour of trace marked in white within frame. Note the termination of the trace showing a small pyrite globule (green arrow). (E) Slab displaying several subparallel specimens in the vicinity of bacterial mats. Note that the relief increase at the surface of the sediment from right to left for each specimen; frame denotes specimen in F. (F) Enlarged part of E, white arrow shows the detail of the trajectory of specimen under the fine clay laminae toward the bacterial mats (yellow arrow). (I and J) Part and counterpart of twinned contorted strings, parting from each other at upper white arrow; box denotes specimen in K. (K) Enlarged part of J; note the contorted strings and braided aspect. (Scale bars: 1 cm.)