Micromorphology of modern epigean termite nests and possible termite ichnofossils: a comparative analysis

COSARINSKY, M., GENISE, J. F AND BELLOSI, E. S

Trelew, Chubut

Congreso; First International Congress on Ichnology; 2004

Museo Paleontológico E. Feruglio

ABSTRACT Micromorphological features may be a powerful tool for comparisons between modern and fossil termite nests, particularly for the correct identification of the latter. Regrettably, micromorphological studies are scarce in the literature. Studies on these features in epigean nests of Neotropical species of termites such as Cornitermes cumulans, Termes saltans, Cortaritermes fulviceps and Nasutitermes sp provided a complete set of data for comparisons. Termitic constructions are evidenced by presence of pellets, coatings and sinuous bands of fecal origin, clay microaggregates, plant remains, and fragments of termite cuticle. Also, by particular types of birefringence fabrics, size and sorting of coarse material, and relative distributions of fine and coarse components. These evidences were tested in ichnofossils attributed to termites in Alfisols and Andisols of Sarmiento Formation, Mollisols of Pinturas Formation and Ultisols of Asencio Formation. The lack of some of these termitic characteres in those ichnofossils can be interpreted as negative evidences. Whereas, the presence of microaggregates and porphyric distribution of fine/coarse components in all specimens, can be taken as positive evidences for a termitic origin of these ichnofossils. However, these characters are also present in the corresponding non-ichnofossiliferous paleosols, suggesting that the acquisition of them could have a non-termitic origin or on the contrary, as shown in modern tropical soils, the incorporation of abandoned termite nests to soils would have played an important role in the formation of these paleosols. More significant is the presence of sinuous and braided bands of organic pigment in ichnofossils of Sarmiento Formation, which are not present in the non-ichnofossiliferous paleosols of this formation.