The Phycosiphon record in the Ladrilleros-Juanchaco section (Miocene, Colombian Pacifi c): palaeoecological implications

Abstract

Miocene rocks of the Ladrilleros-Juanchaco section, located on the NW margin of South America, contain a high diverse and abundant trace fossil assemblage. The relative abundance of Phycosiphon, together with its morphological variations, provides new insights into the environmental conditions. Detailed outcrop stratigraphic, ichnological, and geochemical analyses carried out in the section focused on the trace fossil assemblages (distribution, relative abundance), ichnofabric index, and, especially, in the general ichnological features of Phycosiphon . In addition, the detailed photographic documentation and the use of the digital image treatment technique facilitate the precise study of particular ichnological properties. Based on the stratigraphic analysis of the section, together with the abundance, size and distribution of the specimens of Phycosiphon , as well as the analysis of total organic carbon, the record of Phycosiphon is proved as related to the food content in the sediment, and then as a proxy in the study of ancient environments.