HR: 0800h
AN: GP11D-0869    [Abstracts]
TI: Paleomagnetic and Rock Magnetic Investigation of Leg 210 Cores, Newfoundland Basin
AU: * Liu, Q
EM: qliu@es.ucsc.edu
AF: Institute of Geophysics and Planetary Geophysics, University of California, Santa Cruz, CA 95064 United States
AU: Zhao, X
EM: xzhao@es.ucsc.edu
AF: Institute of Geophysics and Planetary Geophysics, University of California, Santa Cruz, CA 95064 United States
AU: Galbrun, B
AF: Departement of Geology and sedimentology, University of Paris VI, Paris Cedex 5, France, 75252 France
AU: Delius, H
AF: Department of Geology, University of Leicester , Leicester, LE1 7RH United Kingdom
AB: Leg 210, the final leg of the ODP, was devoted to studying the history of rifting and postrift sedimentation in the Newfoundland-Iberia rift. Two sites (Sites 1276 and 1277) were drilled in the central Newfoundland Basin that are along a transect exactly conjugated to the ODP Leg 149/173 drilling sites on the Iberia margin. Site 1276 was cored from 800 to 1739 m below seafloor with excellent recovery of Albian-lower Oligocene sediments and sills (estimated to be 100-200 m above basement). Site 1277 is located about 40 km southeast of Site 1276. Recovered cores from the upper part of basement at this site represent an assemblage of basalt flows, slivers of gabbro, serpentinized peridotite, and sediments. Below these rocks, basement is serpentinized peridotite with veins of gabbro. Stable components of magnetization are revealed in the results of detailed thermal and AF demagnetization on the sediments and diabase sills from Site 1276 and serpentinized peridotites from Site 1277. Azimuths of the maximum anisotropy axis of magnetic susceptibility are used to evaluate the fidelity of the natural magnetic memory of the serpentinized peridotites. Combining the age information available from other Leg 210 studies, we estimated paleolatitudes vs. time for the Newfoundland drill sites. Results from a series of rock magnetic measurements show that (titano)magnetites are present in the diabase sill and serpentinized peridotites, whereas maghemite is mainly responsible for the magnetic signatures displayed in the sedimentary and volcanic succession at Site 1277. These results, in concert with previous paleomagnetic characterization of serpentinized peridotite samples from ODP Legs 149 and 173, provide an inter-basin correlation of the magnetic properties of the peridotite rocks. The magnetic signatures of the serpentinized peridotites recovered from both sides of the Newfoundland-Iberia rift appear not to conflict with the notion that conjugate margins will have generally similar crustal structure and evolution history.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1520 Magnetostratigraphy
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting