A RECORD OF THE UPPER COCHITI POLARITY TRANSITION FROM THE SOUTHERN-HEMISPHERE (FIJI)

We sampled the upper Cochiti polarity transition recorded in the Suva Marl in Fiji (18 degrees S, 178 degrees E). The Suva Marl accumulated at an average rate of 83.2 m/m.y. and provides a unique opportunity to address the question of whether present-day overprints bias the trans ition records. Fiji has undergone a 30 degrees counterclockwise rotati on since the deposition of the Suva Marl and hence a present day overp rint onto the transitions would bias the VGPs toward the east of the s ite. Replicate transition records yield VGPs over both Asia and the Am ericas. Progressive demagnetization reveals a normal polarity overprin t which was acquired prior to the rotation of Fiji, and therefore does not produce an easterly bias to the transition data even after correc tion for the rotation. We collected an oriented block sample across a portion of the transitional interval in the upper Cochiti reversal. Su bsampling of this block into 1.0 cm thick wafers cut parallel to beddi ng provides considerably greater detail during the transition. These d etailed data suggest that the oscillatory movement of the VGPs in thes e sections may be a result of the averaging caused by standard, detail ed minicoring and not by the sediments or the remanence acquisition pr ocess.