XRD analyses indicate various carbonate compositions ranging from pure calcite over low-magnesium to high-magnesium calcite (HMC) (as much as 18 mol% MgCO3) and dolomite, as well as mixtures of different calcitic phases and calcitic and dolomitic phases (Table T1). The grouping of all samples into the three end-member settings (summit, flank, and slope basin) shows significant changes in the mineralogic composition between the settings (Fig. F1). The summit sites are dominated by near-seafloor carbonate precipitation of HMC (12–18 mol% MgCO3). The flank sites indicate carbonate formation in mostly shallow depths to 70 meters below seafloor (mbsf), with various mineralogic compositions ranging from calcite to dolomite. At Site 1244, a calcitic carbonate sample was found in the deep part of the section within highly deformed underthrust sediments of the accretionary complex. The slope basin sites show a bimodal distribution of calcitic and dolomitic carbonates at medium depths at Site 1252 and within the accretionary complex at Site 1251. Carbonates of mixed composition were found at Site 1252 (121–207 mbsf) and in the deeper part of the section at Site 1251, both within the accretionary complex.
Carbonate contents vary between 4 and 74 wt% for the calcitic samples and between 20 and 80 wt% for the dolomitic samples, respectively (Table T1). A clear depth dependency cannot be established (Fig. F2). In general, the solid calcitic pieces have the highest carbonate contents (43–74 wt%). The same holds true for the dolomitic samples (50–76 wt%). In the four depth intervals where dolomites occur (~9, 127, 183, and 305 mbsf) the solid samples always show the highest carbonate content (Fig. F2).