Raman counting: a new method to determine provenance of silt

This article proposes a new integrated methodology to determine the mineralogical composition of silt-sized sediments, reaching the same precision level required to perform quantitative provenance analysis as traditionally done on sand-sized sediments. We examine technical problems encountered in analysis of silt and illustrate how they can be solved for suspended load in a modern fluviodeltaic environment. All methods described here, and specifically the user-friendly Raman spectroscopy, can be routinely applied in mineralogical studies of ancient siltstones. Provenance information can thus be extracted from mudrocks, which represent a very conspicuous part of the stratigraphical record and are prone to preserve original detrital assemblages from diagenetic dissolution better than permeable interlayered sandstones. Quantitative mineralogical analysis of silt-sized sediments by innovative techniques opens up new frontiers in sedimentary petrology. Such an effective approach is of crucial importance to make accurate provenance diagnoses and sediment budgets and to correctly unravel the innumerable pieces of geological information stored in sedimentary archives from the alluvial plain to the deep-sea.