A Cross-Arctic Geophysical Transect Collected from US Coast Guard Icebreaker Healy

During the late Summer of 2005, when the pack ice was at its annual minimum, the US Coast Guard icebreaker Healy undertook a research cruise across the Arctic Ocean. During this cruise, the ship collected continuous multi-beam bathymetry, sub-bottom profiler and gravity anomaly data. As ice conditions permitted, multi-channel seismic reflection and refraction data were collected. The source consisted of two 250 cubic inch airguns. The shots were received by a 200-300 m long streamer (16 to 24 channels) and more than 200 sonobuoy deployments. This cruise crossed all of the major basins and ridges that compose the Arctic Ocean. Ice conditions permitted acquisition of seismic reflection transects over the Chukchi Borderland and Mendeleev Ridge. More difficult ice conditions curtailed seismic work on Alpha Ridge. After rendezvous with the Swedish icebreaker Oden on the western flank of the Alpha Ridge, it was possible to collect MCS data through relatively heavy pack. These operations enabled collection of MCS data in the Makarov Basin and on Lomonosov Ridge. Continuing through the pole, additional data were collected over the Gakkel Ridge and the Yermak Plateau. Data collected in the Amerasian Basin show a pervasive mantled sedimentary layer, consistent with tectonic inactivity of this basin. Some locations lack this layer, suggesting localized erosion by bottom currents. Data collected in the Eurasian Basin will be used to study tectonics of the Gakkel Ridge and the Yermak Plateau.