Bioerosion at all scales is now recognized as playing a major role in facies interpretation. Macroscopic and microscopic borings can provide an indication of water depth, if they can be attributed to the action of specific borers. Tomographic analysis is a new method for assessing bioerosion, for identifying boring taxa, as well as for calculating the volume and porosity in present-day rhodoliths. The tomographic system provides also a quantification of the calcium carbonate produced by bioerosion. Recent rhodoliths collected at 20-m water depth on the Abrolhos Bank, Brazil, have been multi-scanned analyzed. The study shows that rhodoliths from this site are characterized by a highly diversified assemblage of boring bivalves and sponges associated with the ichnogenera Gastrochaenolites and Entobia. The fauna from this boring assemblage can remove up to the 10% of the rhodolith volume. The method can be expected to yield similar results as applied to both modern and fossil rhodoliths from other localities and time frames.
Tomographic analysis for bioerosion signatures in shallow-water rhodoliths from the Abrolhos Bank, Brazil
BASSI, Davide;POSENATO, Renato;
2012
Abstract
Bioerosion at all scales is now recognized as playing a major role in facies interpretation. Macroscopic and microscopic borings can provide an indication of water depth, if they can be attributed to the action of specific borers. Tomographic analysis is a new method for assessing bioerosion, for identifying boring taxa, as well as for calculating the volume and porosity in present-day rhodoliths. The tomographic system provides also a quantification of the calcium carbonate produced by bioerosion. Recent rhodoliths collected at 20-m water depth on the Abrolhos Bank, Brazil, have been multi-scanned analyzed. The study shows that rhodoliths from this site are characterized by a highly diversified assemblage of boring bivalves and sponges associated with the ichnogenera Gastrochaenolites and Entobia. The fauna from this boring assemblage can remove up to the 10% of the rhodolith volume. The method can be expected to yield similar results as applied to both modern and fossil rhodoliths from other localities and time frames.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
