In marine sediments, the Sr content and isotope composition (⁸⁷ Sr/⁸⁶Sr) of the terrigenous detrital component are widely used to track changes in provenance and related transport and weathering processes. Accurately separating detrital-Sr from other sedimentary Sr-phases is a prerequisite for such studies. Conventionally, it is assumed that Sr in the carbonate-free residue corresponds to detrital Sr alone. However, the decarbonated residue may contain barite with significant Sr content and a non-detrital ⁸⁷Sr/⁸⁶Sr composition; this may substantially affect the measured Sr signal. To examine this chronically overlooked phenomenon, the Mediterranean Sea is an ideal areabecause 1) detailed provenance studies have been done using Sr and ⁸⁷Sr/⁸⁶Sr of the residual fraction, and 2) enhanced levels of barite repeatedly occurred in association with distinct, organic-rich sapropel sediments.