Scheffler, Maria; Stein, Ruediger: Elemental analysis (TC, TOC, IC), Rock Eval Pyrolysis, and calcite and dolomite (XRD) data of sediment core PS72/291-2 (Beaufort Sea, Arctic Ocean) [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.984001 (dataset in review)

Core PS72/291-2 (Mackenzie slope/southern Canada Basin; 71°16.18'N, 137°10.82'W; 1502 m of water depth) recovered during Polarstern Expedition PS72 (Jokat, 2009), consists of two lithological units (Stein et al., 2009). Unit I (0 – 152 cm) is characterized by three different types of sediment facies. Facies 1 is a bioturbated brown, grayish brown, and olive brown silty clay (representing post-glacial/Holocene pelagic sedimentation); Facies 2 (90 – 99 cm and 141 – 150 cm) is a dark grayish brown to grayish brown silty clay to sandy silty clay with abundant reddish brown ("pinkish") lenses/clasts and dropstones, and Facies 3 is characterized by dark gray to dark grayish brown laminated fine-grained (silty clay to clay; some sand) sediments. Unit II mainly consists of dark grayish brown, very dark gray to dark olive gray clay, intercalated with thin coarser-grained (silty) layers (fining-upward cycles). Occasionally, small pinkish gray lenses occur. The different sediment facies types were probably controlled by two different main processes. The dominantly dark gray to dark grayish brown silty clay to clay (fining-upward) cycles are interpreted as distal turbidites related to short-term periods of increased suspended matter supply by the Mackenzie River. The second important process of sediment transport towards the core location seems to be ice rafting. Phases of increased IRD input are reflected in the intervals characterized by a more coarse-grained facies with enrichment of pale brown and pinkish lenses/clasts (Stein et al., 2009). This very specific lithology can be related to a restricted source area in the Canadian Arctic (Bank Island, Victoria Island) where Paleozoic carbonates (dolomite) are cropping out (e.g., Phillips and Grantz, 2001; Stein et al., 2010), and it can be interpreted as pulses of increased iceberg discharge due to the disintegration of extended Canadian glacial ice sheets.

For the measurement of bulk parameters by means of elemental analysis and Rock-Eval pyrolysis (Master Thesis of Scheffler, 2012), freeze-dried and homogenized sediments were used. Total organic carbon (TOC) contents were measured by Carbon-Sulfur Analyser (CS-125, Leco) after removing carbonate with hydrochloric acid. Total carbon (TC) contents were determined by Carbon-Nitrogen-Sulfur Analyser (Elementar III, Vario). Inorganic (carbonate) carbon (IC) was calculated as IC = TC-TOC. Rock Eval pyrolysis was performed to get information about composition and maturity of the of the organic matter (e.g., (Peters, 1986; Stein et al., 2006)). During the analysis, (1) the amounts of hydrocarbons (HC) present ("S1 peak") and generated by pyrolytic degradation of the OC during heating up to 650°C ("S2 peak"), (2) the amount of carbon dioxide (CO2) generated from the decomposing OC during heating up to 390 °C, and (3) the temperature of maximum pyrolysis yield (Tmax value in °C) will be determined. The HC and CO2 yields were normalized to OC and expressed as hydrogen index (HI) in mgHC/gOC and oxygen index (OI) in mgCO2/gOC, respectively. As proxy for the OC maturity, the Tmax values were used. Tmax values < 435 °C are indicative for immature OC, whereas mature (ancient/petrogenic) OC has Tmax values between about 435 and 475 °C. In combination with HI values, Tmax values may give further information about the composition as well as the maturity of the organic matter. Furthermore, from the correlation between TOC content and S2 values, the occurrence of "dead carbon" can be estimated to be about 0.3% at Core PS72/291-2 and corrected HI (HI') values can be calculated (for approach see Stein et al., 2006 and further references therein).

Based on XRD data determined on a selected set of samples (Master Thesis of Scheffler, 2012), 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 and calculation procedure see Stein et al., 2010).