1. Data Contacts Dr. Ross Powell (rpowell@niu.edu) Dr. Reed Scherer (reed@niu.edu) Tim Hodson (tohodson@gmail.com) 2. Overview This metadata document describes core scans and lithologic analyses of sediment cores obtained from Subglacial Lake Whillans (SLW), Antarctica. Data include core radiographs, high resolution imagery, XRF core scans, gamma bulk density and magnetic susceptibility core scans, particle size distribution from laser diffraction, and magnetic fabrics. Three coring devices were deployed into SLW: a gravity multi-corer with three 60 mm diameter core barrels designed to recover the soft upper-most sediment and sediment-water interface; a borehole piston corer with a 58 mm diameter core barrel; and a percussion corer with a 10 cm diameter core barrel (Hodgson et al., 2016). Due to a malfunction, percussion-coring was ceased after 10 minutes (approx. 10 blows of the weight). All sediment cores were collected within a 40-hour window, during which time the borehole moved roughly 1m downstream. In total, an 80cm long piston core, a 40 cm long percussion core, and six multicores between 20-40 cm long were recovered. Once the sediment cores reached the surface, they were set vertically for at least two days to allow them to outgas and settle before being laid horizontally for packing and refrigerated (4 C) shipping and long-term storage. Further details pertaining to sample collection are described in (Tulaczyk et al., 2014). Archive halves of the cores are kept at the Antarctic Marine Geology Research Facility, Florida State University, USA. 3. Sample inventory 3.1. WISSARD Sample Naming Convention WISSARD samples use the following naming convention: < site & field season >_< sampling device & deployment & core >_ All samples in this dataset are from the season at SLW (SLW1). Sampling devices include the percussion corer (PEC), piston corer (PC), and multi-corer (MC). The deployment is given by an ordinal number (e.g., 1-3). In addition, one of three cores is specified by the letters A-C for a multicore sample. For example, a 0-10cm sample from the third core (C) of the first multicorer deployment (MC1) would be called: SLW1_MC1A_0-10 3.2. Core inventory Core | Device | Lat | Long | Length (cm) ------------------------------------------------------------------- SLW1_SLW_MC1A | multicorer | -82.375 | -168.625 | 18.5 SLW1_SLW_MC3A | multicorer | -82.375 | -168.625 | 20.5 SLW1_PC1 | piston corer | -82.375 | -168.625 | 74 SLW1_PEC1 | percussion corer | -82.375 | -168.625 | 41 3.3. Additional samples Other samples include soft sediment thin sections and grain mounts of the sand size fraction. Enquires regarding these samples or the availability of sample material should be directed to one of the data contacts. 4. Datasets 4.1. ITRAX XRF Core Scans 4.1.1. Methods High-resolution ED-XRF spectra were logged on the split cores at a 0.3 mm interval using an ITRAX XRF core scanner, which irradiated the sample with a beam generated from a 3 kW Mo target run at 45 kV and 30 mA over a 15 second exposure time. Cores were logged at the Hartshorne Quaternary Lab at University of Massachusetts, Amherst. 4.1.2. Files spectra.tab: XRF elemental abundances in counts per second (cps) document.txt: XRF settings. 4.2. Geotek Core Scans 4.2.1. Methods Gamma ray attenuation bulk density and magnetic susceptibility logged using a Geotek multi-sensor core logger at the Hartshorne Quaternary Lab at University of Massachusetts, Amherst. 4.2.2. Files spectra.tab: ASCII files containing gamma attenuation and magnetic susceptibility and depth. optical.jpg: High-resolution line-scan imagery of the split core. 4.3. Laser Diffraction 4.3.1. Methods 5 grams of sediment was crushed and dry-sieved to remove gravel (>2 mm).ÿ Depending on grain size of the sediment, 0.2 to 5 grams of sieved sample was transferred into a glass bottle with 0.5 ml 5% HMP solution and 30 ml deionized water.ÿ Sample was shaken for 8 hours prior to analysis.ÿ The dispersed sample was transferred to a Malvern Mastersizer 3000 laser diffraction particle size analyzer for particle size analysis.ÿ 4.3.2. Files Excel spreadsheet containing particle size distributions from laser diffraction. 4.4. Radiographs 4.4.1. Methods High-resolution core radiographs of the split cores were taken using a Torrex 120-D radiograph at Antarctic Marine Geology Research Facility, Florida State University. 4.4.2. Files Radiographs of each core. 4.5. Magnetic Fabrics and Granulometry 4.5.1. Methods 2 cm wide oriented paleomagnetic cubes were collected every 4Ð10cm along each core for analysis of anisotropy of magnetic susceptibility (AMS) and natural remnant magnetization (NRM). Samples were taken from the center of the cores to avoid disturbance that typically occurs along the outside edge of the core. Unoriented samples were collected at each depth for magnetic granulometry. Stepwise alternating field (AF) demagnetization and measurement of the NRM was performed using a D-tech D-2000 alternating field demagnetizer and AGICO JR-6 spinner magnetometer. Samples were subjected to peak fields of 0 to 80 mT in 5Ð10mT increments. AMS measurements were made using an AGICO KLY-4 Kappabridge at Montclair State University. The magnetic susceptibility of each cube was measured in 15 orientations, yielding a second-rank susceptibility tensor. 2 cm wide oriented paleomagnetic cubes were collected every 4 to 10 cm along each core for analysis of anisotropy of magnetic susceptibility (AMS). Samples were taken from the center of the cores to avoid disturbance that typically occurs along the outside edge of the core. Unoriented samples were collected at each depth for magnetic granulometry. The magnetic susceptibility of each cube was measured in 15 orientations, yielding a second-rank susceptibility tensor. 4.5.2. Files AMS_results.tab: AMS results. Columns K1, K2, K3 are all dimensionless ratios that describe the magnitude of each axis of the magnetic susceptibility ellipsoid. D1, D2, D3, I1, I2, I3 are all in degrees and describe the declination (D) and inclination (I) of each of the three susceptibility axes (1-3). NRM_raw.tab: Results from the NRM step, which is the very first measurement for all samples, without any prior magnetic treatment (i.e., the 0 mT demagnetization step) NRM_PCA.tab: Principal Component Analysis (PCA) calculation of best fit line for multiple demagnetization steps in order to determine the inclination and declination. 20, 30, 40, and 50 mT demagnetization steps. Only samples for which the maximum angular deviation (MAD value) is less than 5û are included. MAD is a goodness of fit parameter. Smaller MAD is better. 5. References Hodgson, D.A., Bentley, M.J., Smith, A., Klepacki, J., Makinson, K., Smith, M., Saw, K., Scherer, R., Powell, R., Tulaczyk, S., Rose, M., Pearce, D., Mowlem, M., Keen, P., et al., 2016, Technologies for retrieving sediment cores in Antarctic subglacial settings Subject Areas?: Author for correspondence?: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, v. 374, doi: 10.1098/rsta.2015.0056. Tulaczyk, S., Mikucki, J. a., Siegfried, M.R., Priscu, J.C., Barcheck, C.G., Beem, L.H., Behar, A., Burnett, J., Christner, B.C., Fisher, A.T., Fricker, H. a., Mankoff, K.D., Powell, R.D., Rack, F., et al., 2014, WISSARD at Subglacial Lake Whillans, West Antarctica: scientific operations and initial observations: Annals of Glaciology, v. 55, no. 65, p. 51?58, doi: 10.3189/2014AoG65A009.