Expedition 302 geophysics: integrating past data with new results

• Main Authors: Jakobsson, M., Flodén, T., Backman, J., Moran, K., McInroy, D., Brinkhuis, H.K., Clemens, S., Cronin, T., Dickens, G.R., Eynaud, F., Gattacceca, J., Jordan, R.W., Kaminski, M., King, J., Koç, N., Martinez, N.C., Matthiessen, J., Moore, T.C., Onodera, J., O'Regan, M., Pälike, H., Rea, B.R., Rio, D., Sakamoto, T., Smith, D.C., Stein, R., St. John, K.E.K., Suto, I., Suzuki, N., Takahashi, K., Watanabe, M., Yamamoto, M.
• Other Authors: McInroy, D.B., Mayer, L.A.
• Format: Conference Object
• Language: English
• Published: Integrated Ocean Drilling Program Management International, Inc 2006
• Subjects: Arctic; Arctic Ocean; Fram Strait; laptev; Lomonosov Ridge; Sea ice
• Online Access: https://eprints.soton.ac.uk/41915/; https://eprints.soton.ac.uk/41915/1/302_102.PDF; http://www.ecord.org/exp/acex/vol302/EXP_REPT/CHAPTERS/302_102.PDF

In preparation for IODP Expedition 302, Arctic Coring Expedition (ACEX), a site survey database comprising geophysical and geological data from the Lomonosov Ridge was compiled. The accumulated database includes data collected from ice islands, icebreakers, and submarines from 1961 to 2001. In addition, seismic reflection profiles were collected during Expedition 302 that complement the existing seismic reflection data and facilitate integration between the acoustic stratigraphy and the Expedition 302 drill cores. An overview of these data is presented in this chapter. It is well recognized that collecting geophysical data in ice-covered seas, in particular the Arctic Ocean, is a challenging endeavor. This is because much of the Arctic Ocean is continuously covered with ice thicknesses that vary from 1 to 6 m. Over the continental shelves, sea ice can be absent during summer months, but it is present year-round in the central basins. This ice cover is the most dominant feature of the Arctic Ocean environment. It circulates in the ocean basin in two main circulation patterns: the Transpolar Drift and the Beaufort Gyre (see the "Expedition 302 summary" chapter; Rudels et al., 1996). Expedition 302 sites are located within the less severe of these two ice circulation systems, the Transpolar Drift, which primarily moves sea ice from the shelves where it is formed (the Laptev and East Siberian Seas) across the basin and exits through the Fram Strait. During late summer, concentrations of Arctic sea ice can be <100% (10/10 ice cover), making it possible for icebreakers to operate. Average ice concentrations in the central Arctic Ocean during summer months can locally vary from partially open water (6/10) to completely ice covered (10/10). This sea-ice cover can move at speeds up to 0.5 kt. Early Arctic Ocean geophysical exploration was performed from ice-drift stations (Weber and Roots, 1990). However, the tracks from these drifting ice stations were controlled "by the whims of nature" (Jackson et al., 1990), ...