Ichnolithological associations from the Huamampampa Formation: a methodological approach to understand open shelf and estuarine sedimentation during the Devonian of the Sub Andean Foothill, Bolivia

POIRE, DANIEL G.; PEREIRA, MARTÍN; GONZÁLEZ, GLORIA; TINEO, DAVID; VERGANI, GUSTAVO; KAUFMAN, JOHANNA

Mendoza

Congreso; 18 International Sedimentological Congress; 2010

International Association of Sedimentologists

The Huamampampa Formation has been classically interpreted as the product of shallow open-marine sedimentation in a Devonian shelf. However, recent ichnological and sedimentological studies conducted on six cores and some outcrops have allowed the recognition of the occurrence of brackish water sedimentation during the deposition of the Huamampampa Formation.Trace fossils identified in cores and outcrops include Arenicolites, Asterosoma, Bergaueria, Chondrites, Cylindrichnus, Diplocraterion, Helminthopsis, Macaronichnus, Neonereites, Palaeophycus, Phycodes, Planolites, Rhizocorallium, Rosselia, Skolithos, Teichichnus, and Zoophycos.These ichnogenera are grouped in the Cruziana, Skolithos and an impoverished ichnofacies from sections of the Huamampampa Formation analysed along the Sub-Andean foothills in east-southern Bolivia. The aim of this contribution is to show the methodology applied to carry out this study, which includes the measurement every 5 cm of Numerical Facies (NF), Bioturbation Index (BI), Ichnodiversity Index (IdI), Ichnogenus Size Ordering (ISO), and the geostatistic analysis of their obtained curves. Then, ichnofacies and ichnolithological associations have been used to recognise different subenvironments in a tide-dominated delta (or estuarine)-shallow marine environment.