36 New Insights in Atlantic Continental Margin Processes
Tuesday, 13 March 2007
3:00 PM - 4:45 PM
PALEOMAGNETIC INVESTIGATION OF SEDIMENT CORES RECOVERED DURING THE ATLANTIC MARGIN CORING PROJECT (AMCOR)
Paper number: 36-4
Program: THEME SESSIONS
Time: 4:00 PM – 4:20 PM
Authors
Abstract
The paleomagnetic polarity in sediment from 10 cores recovered by the Glomar Conception during the Atlantic Margin Coring Project (AMCOR; Hathaway, et al., 1979) on the Atlantic Ocean continental shelf and slope was determined at the Woods Hole Oceanographic Institution. Two hundred seventeen samples encased in 6.4-cc plastic boxes were treated by alternating field demagnetization and measured in a cryogenic magnetometer. The cores have a diameter of 5.4 cm and were recovered in 9-m pieces that were cut into 1.5-m sections, split, and stored in sealed D tubes in a refrigerated van before transport to Woods Hole, MA. The most reliable data are from a 300-m core (6009B) from the New Jersey outer shelf in water depth 58.5 m at 38¢ª51.3'N, 73¢ª35.5'W where ~120 m of Pleistocene dark gray silty clay and fine sand (Hathaway, et al., 1979) record a possible change from normal to reverse polarity at ~ 90-m depth following demagnetization to 60 mT. The change in polarity is interpreted to be the Matuyama/Brunhes boundary ( ~ 0.78 m.y.) and is a marker horizon in the stratigraphy of the continental shelf.