A GEOPHYSICAL TRANSECT ACROSS THE ARCTIC OCEAN COLLECTED FROM THE US COAST GUARD ICEBREAKER HEALY
COAKLEY, Bernard, Department of Geology and Geophysics, University of Alaska, 900 Yukon Drive, Fairbanks, AK 99775-5789, [email protected], KRISTOFFERSEN, Yngve, Department of Earth Science, University of Bergen, Allegaten 41, Bergen, N-5007, Norway, and HOPPER, John, Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843
The history of the Arctic Ocean is preserved in the pattern of plateaus and sub-basins that segment it and written in the sediments beneath the seafloor. While it is clearly an oceanic basin, to date there is only a single mutually agreed upon plate boundary, the Gakkel Ridge. As a result, reconstructions of the paleogeography of the northern hemisphere prior to Cenozoic times are largely hypothetical. Identifying Arctic plate boundaries will begin the process of deciphering the tectonic history of the Mesozoic Arctic Ocean. This history will provide the context for better understanding the large tectonic features continental margin features that have recently begun to be well mapped. In turn, what is learned from the marine geology will provide critical information towards understanding the terrestrial geologic evolution of major features in the northern hemisphere (e.g., the Brooks Range and North Slope of Alaska and the Chukchi Shelf).
During the late Summer of 2005 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 nearly 100 sonobuoy deployments.
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.
The stratigraphic record of the Arctic Ocean is revealed in the ~2200 km of
multi-channel seismic reflection
data collected during this cruise. These
sediments contain a unique paleo-oceanographic and climatic record. Very little
of the Cenozoic and almost none of the Mesozoic record has been directly
sampled. Deciphering this history will complement the sediment and ice cores
taken at lower latitudes and extend the limited historical time series for the
high arctic, making it possible to study truly global paleo-climate for the
first time.