DOI: 10.18739/a2wp9t74j
title: Marine and sub ice shelf cores collected from Petermann glacier using icebreaker Oden (OD1507), Greenland 2015

description: The Petermann Glacier is located in North-West Greenland where it drains the northwestern sector of the Greenland Ice Sheet (GIS) into the Nares Strait. It is a so-called tidewater glacier, also known as outlet glacier, with an approximately 70 kilometers (km) long and 15 km wide floating ice tongue, or small ice shelf. The floating portion varies in thickness from ∼600 meters (m) where it is grounded at the seabed in the inner part of the fjord to ∼30–80 m at its front.
 The Petermann Glacier 2015 expedition with icebreaker (IB) Oden focused on investigating marine cryospheric and oceanographic changes in the Petermann Glacier-Fjord and adjacent Nares Strait region that are accessible in geologic records. Long term records of variations of glaciers draining the GIS into the ocean and their interaction with the ocean are required to fully understand the dynamics of the GIS.
 The Petermann Glacier is a well-suited target because it terminates in an extensive floating ice shelf that is sensitive to ice/ocean interactions. Finally, the Nares Strait is a conduit for southward flow of low-salinity waters, with oceanographic impacts.
 Petermann Glacier is connected to the inland ice through an ancient (perhaps pre-glacial) channel system, which extends from Petermann Fjord, deep into the inland ice along a pathway near the North Greenland Eemian Ice Drilling (NEEM) and North Greenland Ice Core Project (NGRIP) ice cores.
 The expedition examined the relatively unexplored outlet end of this large system, by documenting changes in the grounded Petermann Glacier, its buttressing ice shelf, and ocean conditions since the end of the last glacial period. Primary scientific questions included:
 1. How sensitive is Petermann ice shelf extent to documented climate changes within the Holocene?
 2. Is ice-shelf response independent of, or linked to, variations in the grounded Petermann Glacier, ocean thermal conditions, or relative sea level (i.e., sill depth)?
 3.What are the rates of change and variability of these systems in response to early Holocene warming, Neoglacial cooling, and post-Neoglacial (late 19th-century to present) warming?
 Analyses of the acquired sediment cores was one of the main focuses of the Petermann program. The future use of the data is abundant, i.e. paleoclimate reconstructions, paleoceanography, sediment geochemistry.
 The coring involved both piston/gravity coring for up to 40 foot (12m) long cores and multi-coring specifically targeting the uppermost surface sediment sequence. Exact coring locations were selected at sea based on geophysical survey mapping. This data package includes coring data sheets as well as meta data for the cores collected on the Petermann 2015 (OD1507) expedition on the IB Oden.
 The cores were first measured for sediment physical properties then split photographed and visually described. This data package includes MSCL (or MST data) as well as split core images and visual sedimentological core descriptions.
 GEOTEK Multi-Sensor Core Logger (MSCL or MST) is a fully automated core logging system equipped with transducers for measuring compressional wave velocity, magnetic susceptibility sensors for measuring the volume of magnetic minerals within cores, and a Cs-137 radioactive source for measuring the bulk density of sediments.
 Analyses of sediment physical properties provides a basis for initial stratigraphic interpretations, inter-core correlation and planning for more detailed subsampling strategies.
 Split-Core Photography. Core photographs were taken using a GEOSCAN III Line Scan Camera System using the Geotek XZ track system.
 Cores were kept in a refrigerated container van at 40 degree Fahrenheit (F) or 4 degree Celsius (C) on board the IB Oden and were transported refrigerated until they arrived at the Oregon State University Marine and Geology Repository (OSU-MGR) in Corvallis, Oregon USA, where they are still held at 40F (4C).
 Computed tomography (CT) scans of the most promising sediment cores were made on a Toshiba Aquilion 64 Slice Medical CT Scanner at the OSU College of Veterinary Medicine at 120 Kilovolt (kV), converted into 2 millimeters (mm) thick coronal slices with an effective in-plane resolution of about 0.5 x 0.5 mm, and processed using SedCT MATLAB tools (Reilly et al., 2017). X-ray Fluorescence (XRF) scans were made using the OSU Marine and Geology Repository ITRAX XRF Core Scanner, using a Mo Tube and 5 s exposure time. This data package includes CT scans as well as XRF data of a selected group of cores.