A novel application of digital image treatment by quantitative pixel analysis to trace fossil research in marine cores

Ichnological analysis in cores has grown substantially in the past two decades because of its importance in fields such as paleoecology, biostratigraphy, or reservoir characterization. Yet core analysis entails some added difficulties in comparison to ichnological outcrop study, especially in modern marine sediments. Quantitative pixel analysis conducted on high-resolution images is used to facilitate the study of bioturbation in marine cores from site U1385 of IODP Expedition 339 in the Gulf of Cádiz. Lateral and vertical variation of pixel values obtained from the infilling trace fossils and from the host sediment are revealed to be highly useful to: (1) differentiate between trace fossils and biodeformational structures, including the host sediment; (2) discriminate between ichnotaxa (i.e., Palaeophycus vs. Planolites); (3) differentiate between passively and actively infilled structures (e.g., Thalassinoides vs. Planolites), and (4) characterize the horizon of bioturbation and thus evaluate the depth of penetration of particular tracemakers.