The armored burrow Nummipera eocenica from the upper Eocene San Jacinto Formation, Colombia: morphology and paleoenvironmental implications

Abstract

The ichnospecies Nummipera eocenica occurs in thick-bedded, tabular bioclastic massive sandstone of the upper Eocene San Jacinto Formation in the San Jacinto Fold Belt Basin, Colombia. Nummipera eocenica is a vertical to oblique burrow locally displaying a conical shape. The lining structure of the specimens studied consists of uniformly distributed lepidocyclinids and operculinids, with tests typically dipping towards the burrow wall, and well-compacted lining. The burrow infill is identical to the host rock, a bioclastic sandstone with abundant bivalve fragments. The diagnosis of Nummipera is emended to include as components of burrow lining all representatives of the Subclass Rotaliana characterized by being lenticular to discoidal in shape. In the San Jacinto Formation, Nummipera eocenica is present in the transition between deltaic mouth-bar and carbonate platform deposits.

Keywords:

• Armored burrows
• ichnology
• San Jacinto Fold Belt Basin
• larger benthic foraminifera

Acknowledgements

Thanks to Jose Gabriel Mendoza for field work assistance and Zain Belaústegui for valuable feedback on the taxonomy of armored burrows. Comments by Renata Jach and an anonymous reviewer improved the manuscript and are greatly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We thank the Instituto Colombiano del Petróleo ICP-Ecopetrol S.A for funding this study.