Core PS72/287-3 SL (74°15.95'N, 90°59.09'W; water depth 337 m) was recovered in Barrow Strait in the Canadian Arctic Archipelago during the Polarstern Expedition PS72 in 2008 (Jokat, 2009). The 463 cm long sedimentary section can be divided into two lithological units (Stein et al., 2009). Unit I (0-312 cm) is mainly composed of olive brown (upper 33 cm) and olive gray to (dark) grayish brown, partly bioturbated silty clay to sandy silty clay. Ice-rafted debris (IRD) > 2mm only occur in minor amounts, with minimum values (almost absence) between about 100 and 250 cm and increasing number in the uppermost 70 cm. Unit II (312-463 cm) dominantly consists of grayish brown, light grayish brown, and light gray to gray sandy silty clay and silty clay with common occurrence of dropstones. The occurrence of dropstones ranging in size from 0.5 to 7 cm in diameter, is the main difference to Unit I. Dropstones are especially enriched between 378 and 399 cm, between 412 and 428 cm, and in the lowermost part of the core, classifying the sediment as diamicton. Unit II probably represent the final stage of the last glaciation and/or the deglacial period. An extended ice sheet and its subsequent decay resulted in the formation of diamictons and large input of IRD at the core location. Unit I represents the post-glacial Holocene time interval when seasonally open-marine conditions were predominant (Stein et al., 2009). In order to reconstruct the detrital sediment provenance, transport processes and ice-sheet history, X-Ray diffraction (XRD) analyses were carried-out using ground bulk sediment (cf., Vogt, 1997; Phillips and Grantz, 2001; Stein et al., 2010). The relative contents of the determined minerals are expressed as ratio of the XRD single mineral peak intensity vs. sum of total analyzed intensities (Vogt, 2009). In addition, total organic carbon (TC), total organic carbon (TOC) and inorganic carbon (IC) calculated as TC - TOC = IC, have been determined from the same set of samples (Master Thesis of Zhelesnov, 2008).Based on the XRD data, the major proportion of the inorganic carbon is related to dolomite and calcite whereas aragonite and siderite only occur in very, very minor amounts. Thus, for getting a first-order estimate of the detrital carbonate (dolomite), the inorganic carbon was simply divided into its calcite and dolomite proportions using the relative intensity values of the calcite (3.04 Å) and dolomite (2.89 Å) XRD peaks and assuming that calcite plus dolomite equals to the total carbonate content (IC) (for details see Stein et al., 2010). The geology of the surrounding hinterland of Core PS72/287 is dominated by Paleozoic carbonates, siliciclastics and evaporites (Okuma et al., 2023 and further references therein), also reflected in the high dolomite content determined in this core (20 to 45 %).
