Marine and sub ice shelf cores collected from Petermann glacier using icebreaker Oden (OD1507), Greenland 2015

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.格陵兰彼得曼冰川（Petermann Glacier）位于格陵兰岛西北部，承接格陵兰冰原（Greenland Ice Sheet, GIS）的西北区域径流，注入内尔斯海峡（Nares Strait）。该冰川属于潮汐冰川（tidewater glacier），亦称为出口冰川（outlet glacier），拥有长约70千米、宽约15千米的浮动冰舌，即小型冰架。浮动冰体的厚度从峡湾内底部接地处的约600米，变化至冰前缘的30至80米不等。 2015年搭载破冰船（Icebreaker, IB）Oden的彼得曼冰川考察队，重点研究了彼得曼峡湾及邻近内尔斯海峡区域可通过地质记录获取的海洋冰冻圈与海洋学变化。要全面理解格陵兰冰原的动力学机制，需获取格陵兰冰原入海冰川变化及其与海洋相互作用的长期记录。彼得曼冰川是理想的研究目标，因其终止于广泛分布的浮动冰架，对冰-海洋相互作用极为敏感。此外，内尔斯海峡是低盐水向南流动的通道，具有显著的海洋学影响。 彼得曼冰川通过一套古老（可能为冰期前的）水道系统与内陆冰相连，该水道系统从彼得曼峡湾延伸，沿北格陵兰埃姆冰钻（North Greenland Eemian Ice Drilling, NEEM）与北格陵兰冰芯计划（North Greenland Ice Core Project, NGRIP）冰芯附近的路径深入内陆冰区。本次考察对该大型系统相对未被探索的出口端进行了研究，通过记录末次冰期结束以来接地彼得曼冰川、其支撑性冰架以及海洋环境的变化，解析相关过程。本次考察的核心科学问题包括： 1. 全新世以来有记录的气候变化对彼得曼冰架范围的敏感性如何？ 2. 冰架的响应是独立于接地彼得曼冰川、海洋热状况或相对海平面（即门槛深度）的变化，还是与之相关联？ 3. 这些系统在早全新世变暖、新冰期变冷以及新冰期后（19世纪末至今）变暖过程中的变化速率与变异性如何？ 沉积物岩芯分析是本次彼得曼科考项目的核心内容之一。本数据集的未来应用场景广泛，涵盖古气候重建、古海洋学研究以及沉积物地球化学分析。本次取芯工作包括用于获取最长12米（40英尺）岩芯的活塞/重力取芯，以及专门针对表层最上部沉积物序列的多管取芯。取芯点位通过海上地球物理勘测绘图选定。本数据包包含2015年彼得曼考察（OD1507）期间在IB Oden上采集的岩芯数据表及岩芯元数据。 岩芯首先被测量沉积物物理性质，随后进行拆分、拍照并开展目视描述。本数据包包含MSCL（或称MST数据）、拆分岩芯图像以及目视沉积学岩芯描述。GEOTEK多传感器岩芯测井系统（MSCL，或称MST）为全自动岩芯测井系统，配备用于测量纵波速度的换能器、用于测定岩芯内磁性矿物含量的磁化率传感器，以及用于测量沉积物体密度的Cs-137放射源。沉积物物理性质分析可为初步地层解释、岩芯间对比以及制定更详细的分样策略提供基础依据。 拆分岩芯摄影：采用搭载Geotek XZ轨道系统的GEOSCAN III线扫描相机系统拍摄岩芯照片。科考期间，岩芯被保存在40华氏度（约4摄氏度）的冷藏集装箱车内，并全程冷藏运输至美国俄勒冈州科瓦利斯的俄勒冈州立大学海洋与地质资源库（OSU-MGR），目前该批岩芯仍保存于40℉（4℃）环境中。 对最具研究价值的沉积物岩芯开展了计算机断层扫描（Computed tomography, CT）：使用俄勒冈州立大学兽医学院的Toshiba Aquilion 64层医用CT扫描仪，参数设置为120千伏（kV），扫描结果转换为厚度2毫米（mm）的冠状切片，有效面内分辨率约为0.5×0.5 mm，并使用SedCT MATLAB工具（Reilly等人，2017）进行处理。X射线荧光（X-ray Fluorescence, XRF）扫描采用俄勒冈州立大学海洋与地质资源库的ITRAX XRF岩芯扫描仪完成，使用钼靶管，曝光时长5秒。本数据包包含选定岩芯组的CT扫描图像及XRF数据。