9321628 Brozena and Kovacs This award supports a geophysical investigation of the northern Canada Basin, part of the Arctic Ocean basin. A well constrained understanding of the tectonic evolution of the Canada Basin is critical for determining the geological evolution of the northern margins of Alaska, Canada, and Siberia, and for determining the tectonic framework under which paleoclimatic change occurred. The current regional geophysical knowledge of the region is not complete enough to adequately constrain even zeroth-order tectonic models of the evolution of the region. This is reflected in the continuing scientific controversy over the timing and most basic tectonic characteristics of those models. This project will conduct a regional aerogravity- aeromagnetic investigation of the northern Canada Basin with the goal of determining the structure and tectonic evolution of this region. To conduct these flights, Naval Research Laboratory (NRL) will deploy its RP-3 Orion long-range aircraft equipped with the NRL Airborne Geophysical Sensor Suite (AGSS) from Pt. Barrow, Alaska for a one to two month study over a section of the Canada Basin chosen to provide the highest likelihood of important tectonic signatures diagnostic of opening direction and timing. Funds from NSF will partially support one month of the field program. NRL will support the balance of the costs with internal research funds and support from other Federal agencies. The AGSS consists of multiple redundant gravimeter, kinematic GPS, and radar/laser altimeter systems in addition to a standard airborne proton precession magnetometer. This system has successfully collected over 200,000 line-km of high quality gravity, magnetics, and topography data over Greenland in 1991 and 1992. In addition, 40,000 line-km of similar data were collected over the northern Canada Basin adjacent to Arctic Canada in 1992 as a pilot program for the proposed work. Typically, the accuracy of the system at the altitudes and speeds proposed (600m and 240 knots) is about 2- 3 mGal (root-mean-square) at the track crossings, resolving crustal features with wavelengths of 15 km and longer. The project will be performed under the framework of a cooperative, international program involving scientists from the United States, Canada, and Russia. This work will yield an geophysical data set that will be used to interpret the tectonic and geologic evolution of the region but the data set will also be used by many parts of the broader earth sciences community.
