## Abstract

BASSI, D.; IRYU, Y., and NEBELSICK, J.H., 2012. To be or not to be a fossil rhodolith? Analytical methods for studying fossil rhodolith deposits.

The past environment is often reconstructed by measuring certain proxy data, such as changes in oxygen isotopes, taxonomic assemblages, and taphonomic signatures in a palaeoenvironmental archive (e.g., rhodoliths, corals, invertebrate shells, trees, ice cores, speleothems, etc.). Proxy analysis usually yields a record that has to be compared with present-day analogues to yield meaningful results. This also holds true for the interpretation of the palaeoenvironment of rhodolith deposits. The characteristics of Recent rhodoliths and the environments in which they are formed, thus, need to be known to interpret their fossil counterparts. The comparison of fossil and Recent rhodoliths and their environment is, however, not straightforward because the respective analytical methods applied to them are usually different and often difficult to reconcile. To reduce the uncertainties of this problem and to facilitate direct comparisons, we describe a number of analytical methods applied to fossil rhodoliths that can also be performed on Recent material. The analytical methods introduced here correspond to three different scales of analysis: (1) the outcrop scale as completed in field studies and the study of (2) isolated specimens and (3) thin sections in the laboratory.