The top Olduvai polarity transition at ODP Site 983 (Iceland Basin)

The composite section obtained from ODP Site 983 has been sampled in the vicinity of the top Olduvai polarity transition using the u-channel technique. The polarity transition occurs in a normalized remanence (paleointensity) low with post-reversal recovery in paleointensity but no systematic decay in paleointensity in the Matuyama Chron above the reversal. The directional change associated with the reversal extends over about one meter depth, with a virtual geomagnetic pole (VGP) path which indicates a number of loops over Canada and the North Atlantic, prior to a path over the Americas to a VGP cluster in the South Atlantic, off Argentina. The path then leads to a VGP cluster over India, then a loop over the Caribbean and transits through the Atlantic to high southerly latitudes. VGP clusters in the transition path are observed at positions which are broadly similar to those seen in the top Jaramillo transition at the same site, may imply a memory effect in the geodynamo spanning successive reversals of the same sense.