HR: 1340h
AN: T13A-1135    [Abstracts]
TI: Mapping Geomagnetic Field Variations in the Cretaceous Quiet Zone with Unmanned Airborne Vehicles
AU: * Gee, J S
EM: jsgee@ucsd.edu
AF: Scripps Institution of Oceanography, Geosciences Res. Div., La Jolla, CA 92093, United States
AU: Cande, S C
EM: scande@ucsd.edu
AF: Scripps Institution of Oceanography, Geosciences Res. Div., La Jolla, CA 92093, United States
AU: Kent, D V
EM: dvk@rci.rutgers.edu
AF: Rutgers University, Dept. Geological Sci., Piscataway, NJ 08854, United States
AB: About one quarter of the present seafloor was generated during the constant normal polarity interval from 121 to 83 Ma (Cretaceous Quiet Zone or KQZ), and the lack of temporal markers limits tectonic reconstructions in these areas. Although magnetostratigraphic studies provide strong evidence that the KQZ formed during predominantly normal polarity, there are nonetheless relatively large amplitude variations in many sea surface magnetic anomaly profiles crossing KQZ crust. To evaluate the relative importance of geomagnetic and crustal variables (thickness, geochemistry) in generating these anomalies, we collected multibeam bathymetry and magnetic data on 19 profiles crossing anomaly 34 and extending 500 km into the KQZ in the southwest Pacific. The relatively fast spreading (60 km/m.y. half rate), minimal sediment cover and high paleolatitude of formation make this area ideal for evaluating the magnetic anomaly pattern. An additional 10,000 km of magnetic anomaly data were acquired using an autonomous unmanned airborne vehicle (UAV). Although land-launched UAVs have been used in a variety of research applications, the nine successful flights during our cruise represent the first deployment from a UNOLS research vessel. The UAV (operated by Fugro Airborne) was launched from a pneumatic catapult and captured by a wingtip clip that attaches to a rope suspended from a retractable boom on the fantail. The Cs-vapor magnetometer data from the UAV compare favorably with results from the surface-towed magnetometer, with minor differences related primarily to the higher elevation (120m above sea level) of the UAV. The resulting magnetic coverage indicates that, as with younger seafloor, quasi-linear short wavelength anomalies are present within the KQZ. These anomalies can vary on spatial scales smaller than the multibeam swath width, highlighting the utility of obtaining additional coverage with the UAVs.
DE: 1517 Magnetic anomalies: modeling and interpretation
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1550 Spatial variations attributed to seafloor spreading (3005)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting