Fluvial Environments - Trace Fossils as Indicators of Sedimentary Environments - page 335

FIGURE 4 Examples of trace fossils from the Termitichnus Ichnofacies (A and B) and other trace
fossils from paleosol assemblages of uncertain ichnofacies (C-F). (A) Two Termitichnus specimens
below a cornice (arrows). (B) Dense rhizoliths of different diameters and Fleaglellius (arrows).
(C) Rounded end of a large vertebrate burrow cast with abundant rhizoliths. (D) Subhorizontal
branched siliceous rhizoliths (arrows). (E) Profuse small siliceous rhizoliths (some arrowed) in a
vertical outcrop face. (F) Intensely bioturbated ichnofabric with at least two discrete Loloichnus
specimens (J-, Y-shaped vertical burrow; arrows). The examples are from paleosols of the
Oligocene Jebel Qatrani Formation in Egypt (A, B); from a silicified calcrete and silcrete horizons
of the Middle Triassic Tarjados Formation in La Rioja province, Argentina (C-E); and from a vol-
caniclastic paleosol of the Early Cretaceous Punta del Barco Formation in Santa Cruz province,
Argentina (F).

3.5 Ichnofacies

A few trace-fossil assemblages in fluvial deposits can be assigned to the
Mermia Ichnofacies ( Buatois and M´ngano, 2002, 2004 ) and are represented
by seven cases ( Fig. 1 E). This ichnofacies is represented by low-diversity asso-
ciations of simple burrows/trails ( Fig. 5 A and B), complex sinusoidal trails,
arthropod trackways, and/or horizontal burrows, almost exclusively found in

Mermia